Question: What is WebhookConfiguration?

Answer: A p p e a r s   i n :   A u t h o r i z e r C o n f i g u r a t i o n   T h e   d u r a t i o n   t o   c a c h e   ' a u t h o r i z e d '   r e s p o n s e s   f r o m   t h e   w e b h o o k   a u t h o r i z e r .   S a m e   a s   s e t t i n g   - - a u t h o r i z a t i o n - w e b h o o k - c a c h e - a u t h o r i z e d - t t l   f l a g   D e f a u l t :   5 m 0 s   T h e   d u r a t i o n   t o   c a c h e   ' u n a u t h o r i z e d '   r e s p o n s e s   f r o m   t h e   w e b h o o k   a u t h o r i z e r .   S a m e   a s   s e t t i n g   - - a u t h o r i z a t i o n - w e b h o o k - c a c h e - u n a u t h o r i z e d - t t l   f l a g   D e f a u l t :   3 0 s   T i m e o u t   f o r   t h e   w e b h o o k   r e q u e s t   M a x i m u m   a l l o w e d   v a l u e   i s   3 0 s .   R e q u i r e d ,   n o   d e f a u l t   v a l u e .   T h e   A P I   v e r s i o n   o f   t h e   a u t h o r i z a t i o n . k 8 s . i o   S u b j e c t A c c e s s R e v i e w   t o   s e n d   t o   a n d   e x p e c t   f r o m   t h e   w e b h o o k .   S a m e   a s   s e t t i n g   - - a u t h o r i z a t i o n - w e b h o o k - v e r s i o n   f l a g   V a l i d   v a l u e s :   v 1 b e t a 1 ,   v 1   R e q u i r e d ,   n o   d e f a u l t   v a l u e   M a t c h C o n d i t i o n S u b j e c t A c c e s s R e v i e w V e r s i o n   s p e c i f i e s   t h e   S u b j e c t A c c e s s R e v i e w   v e r s i o n   t h e   C E L   e x p r e s s i o n s   a r e   e v a l u a t e d   a g a i n s t   V a l i d   v a l u e s :   v 1   R e q u i r e d ,   n o   d e f a u l t   v a l u e   C o n t r o l s   t h e   a u t h o r i z a t i o n   d e c i s i o n   w h e n   a   w e b h o o k   r e q u e s t   f a i l s   t o   c o m p l e t e   o r   r e t u r n s   a   m a l f o r m e d   r e s p o n s e   o r   e r r o r s   e v a l u a t i n g   m a t c h C o n d i t i o n s .   V a l i d   v a l u e s :   N o O p i n i o n :   c o n t i n u e   t o


Question: What is WebhookConnectionInfo?

Answer: A p p e a r s   i n :   W e b h o o k C o n f i g u r a t i o n   C o n t r o l s   h o w   t h e   w e b h o o k   s h o u l d   c o m m u n i c a t e   w i t h   t h e   s e r v e r .   V a l i d   v a l u e s :   K u b e C o n f i g F i l e :   u s e   t h e   f i l e   s p e c i f i e d   i n   k u b e C o n f i g F i l e   t o   l o c a t e   t h e   s e r v e r . I n C l u s t e r C o n f i g :   u s e   t h e   i n - c l u s t e r   c o n f i g u r a t i o n   t o   c a l l   t h e   S u b j e c t A c c e s s R e v i e w   A P I   h o s t e d   b y   k u b e - a p i s e r v e r .   T h i s   m o d e   i s   n o t   a l l o w e d   f o r   k u b e - a p i s e r v e r .   P a t h   t o   K u b e C o n f i g F i l e   f o r   c o n n e c t i o n   i n f o   R e q u i r e d ,   i f   c o n n e c t i o n I n f o . T y p e   i s   K u b e C o n f i g


Question: What is WebhookMatchCondition?

Answer: A p p e a r s   i n :   W e b h o o k C o n f i g u r a t i o n   e x p r e s s i o n   r e p r e s e n t s   t h e   e x p r e s s i o n   w h i c h   w i l l   b e   e v a l u a t e d   b y   C E L .   M u s t   e v a l u a t e   t o   b o o l .   C E L   e x p r e s s i o n s   h a v e   a c c e s s   t o   t h e   c o n t e n t s   o f   t h e   S u b j e c t A c c e s s R e v i e w   i n   v 1   v e r s i o n .   I f   v e r s i o n   s p e c i f i e d   b y   s u b j e c t A c c e s s R e v i e w V e r s i o n   i n   t h e   r e q u e s t   v a r i a b l e   i s   v 1 b e t a 1 ,   t h e   c o n t e n t s   w o u l d   b e   c o n v e r t e d   t o   t h e   v 1   v e r s i o n   b e f o r e   e v a l u a t i n g   t h e   C E L   e x p r e s s i o n .   ' r e s o u r c e A t t r i b u t e s '   d e s c r i b e s   i n f o r m a t i o n   f o r   a   r e s o u r c e   a c c e s s   r e q u e s t   a n d   i s   u n s e t   f o r   n o n - r e s o u r c e   r e q u e s t s .   e . g .   h a s ( r e q u e s t . r e s o u r c e A t t r i b u t e s )   & &   r e q u e s t . r e s o u r c e A t t r i b u t e s . n a m e s p a c e   = =   ' d e f a u l t ' ' n o n R e s o u r c e A t t r i b u t e s '   d e s c r i b e s   i n f o r m a t i o n   f o r   a   n o n - r e s o u r c e   a c c e s s   r e q u e s t   a n d   i s   u n s e t   f o r   r e s o u r c e   r e q u e s t s .   e . g .   h a s ( r e q u e s t . n o n R e s o u r c e A t t r i b u t e s )   & &   r e q u e s t . n o n R e s o u r c e A t t r i b u t e s . p a t h   = =   ' / h e a l t h z ' . ' u s e r '   i s   t h e   u s e r   t o   t e s t   f o r .   e . g .   r e q u e s t . u s e r   = =   ' a l i c e ' ' g r o u p s '   i s   t h e   g r o u p s   t o   t e s t   f o r .   e . g .   ( ' g r o u p 1 '   i n   r e q u e s t . g r o u p s ) ' e x t r a '   c o r r e s p o n d s   t o   t h e   u s e r . I n f o . G e t E x t r a ( )   m e t h o d   f r o m   t h e   a u t h e n t i c a t


Question: What is Exposing an External IP Address to Access an Application in a Cluster?

Answer: Exposing an External IP Address to Access an Application in a ClusterThis page shows how to create a Kubernetes Service object that exposes an external IP address.Before you beginInstall kubectl.Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an external load balancer, which requires a cloud provider.Configure kubectl to communicate with your Kubernetes API server. For instructions, see the documentation for your cloud provider.ObjectivesRun five instances of a Hello World application.Create a Service object that exposes an external IP address.Use the Service object to access the running application.Creating a service for an application running in five podsRun a Hello World application in your cluster:service/load-balancer-example.yaml apiVersion: apps/v1 kind: Deployment metadata: labels: app.kubernetes.io/name: load-balancer-example name: hello-world spec: replicas: 5 selector: matchLabels: app.kubernetes.io/name: load-balancer-example template: metadata: labels: app.kubernetes.io/name: load-balancer-example spec: containers: - image: gcr.io/google-samples/hello-app:2.0 name: hello-world ports: - containerPort: 8080 kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml The preceding command creates a Deployment and an associated ReplicaSet. The ReplicaSet has five Pods each of which runs the Hello World application.Display information about the Deployment:kubectl get deployments hello-world kubectl describe deployments hello-world Display information about your ReplicaSet objects:kubectl get replicasets kubectl describe replicasets Create a Service object that exposes the deployment:kubectl expose deployment hello-world --type=LoadBalancer --name=my-service Display information about the Service:kubectl get services my-service The output is similar to:NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s Note:The type=LoadBalancer service is backed by external cloud providers, which is not covered in this example, please refer to this page for the details.Note:If the external IP address is shown as <pending>, wait for a minute and enter the same command again.Display detailed information about the Service:kubectl describe services my-service The output is similar to:Name: my-service Namespace: default Labels: app.kubernetes.io/name=load-balancer-example Annotations: <none> Selector: app.kubernetes.io/name=load-balancer-example Type: LoadBalancer IP: 10.3.245.137 LoadBalancer Ingress: 104.198.205.71 Port: <unset> 8080/TCP NodePort: <unset> 32377/TCP Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more... Session Affinity: None Events: <none> Make a note of the external IP address (LoadBalancer Ingress) exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of Port and NodePort. In this example, the Port is 8080 and the NodePort is 32


Question: How does Exposing an External IP Address to Access an Application in a Cluster work?

Answer: Exposing an External IP Address to Access an Application in a ClusterThis page shows how to create a Kubernetes Service object that exposes an external IP address.Before you beginInstall kubectl.Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an external load balancer, which requires a cloud provider.Configure kubectl to communicate with your Kubernetes API server. For instructions, see the documentation for your cloud provider.ObjectivesRun five instances of a Hello World application.Create a Service object that exposes an external IP address.Use the Service object to access the running application.Creating a service for an application running in five podsRun a Hello World application in your cluster:service/load-balancer-example.yaml apiVersion: apps/v1 kind: Deployment metadata: labels: app.kubernetes.io/name: load-balancer-example name: hello-world spec: replicas: 5 selector: matchLabels: app.kubernetes.io/name: load-balancer-example template: metadata: labels: app.kubernetes.io/name: load-balancer-example spec: containers: - image: gcr.io/google-samples/hello-app:2.0 name: hello-world ports: - containerPort: 8080 kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml The preceding command creates a Deployment and an associated ReplicaSet. The ReplicaSet has five Pods each of which runs the Hello World application.Display information about the Deployment:kubectl get deployments hello-world kubectl describe deployments hello-world Display information about your ReplicaSet objects:kubectl get replicasets kubectl describe replicasets Create a Service object that exposes the deployment:kubectl expose deployment hello-world --type=LoadBalancer --name=my-service Display information about the Service:kubectl get services my-service The output is similar to:NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s Note:The type=LoadBalancer service is backed by external cloud providers, which is not covered in this example, please refer to this page for the details.Note:If the external IP address is shown as <pending>, wait for a minute and enter the same command again.Display detailed information about the Service:kubectl describe services my-service The output is similar to:Name: my-service Namespace: default Labels: app.kubernetes.io/name=load-balancer-example Annotations: <none> Selector: app.kubernetes.io/name=load-balancer-example Type: LoadBalancer IP: 10.3.245.137 LoadBalancer Ingress: 104.198.205.71 Port: <unset> 8080/TCP NodePort: <unset> 32377/TCP Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more... Session Affinity: None Events: <none> Make a note of the external IP address (LoadBalancer Ingress) exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of Port and NodePort. In this example, the Port is 8080 and the NodePort is 32


Question: When would you use Exposing an External IP Address to Access an Application in a Cluster?

Answer: Exposing an External IP Address to Access an Application in a ClusterThis page shows how to create a Kubernetes Service object that exposes an external IP address.Before you beginInstall kubectl.Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an external load balancer, which requires a cloud provider.Configure kubectl to communicate with your Kubernetes API server. For instructions, see the documentation for your cloud provider.ObjectivesRun five instances of a Hello World application.Create a Service object that exposes an external IP address.Use the Service object to access the running application.Creating a service for an application running in five podsRun a Hello World application in your cluster:service/load-balancer-example.yaml apiVersion: apps/v1 kind: Deployment metadata: labels: app.kubernetes.io/name: load-balancer-example name: hello-world spec: replicas: 5 selector: matchLabels: app.kubernetes.io/name: load-balancer-example template: metadata: labels: app.kubernetes.io/name: load-balancer-example spec: containers: - image: gcr.io/google-samples/hello-app:2.0 name: hello-world ports: - containerPort: 8080 kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml The preceding command creates a Deployment and an associated ReplicaSet. The ReplicaSet has five Pods each of which runs the Hello World application.Display information about the Deployment:kubectl get deployments hello-world kubectl describe deployments hello-world Display information about your ReplicaSet objects:kubectl get replicasets kubectl describe replicasets Create a Service object that exposes the deployment:kubectl expose deployment hello-world --type=LoadBalancer --name=my-service Display information about the Service:kubectl get services my-service The output is similar to:NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s Note:The type=LoadBalancer service is backed by external cloud providers, which is not covered in this example, please refer to this page for the details.Note:If the external IP address is shown as <pending>, wait for a minute and enter the same command again.Display detailed information about the Service:kubectl describe services my-service The output is similar to:Name: my-service Namespace: default Labels: app.kubernetes.io/name=load-balancer-example Annotations: <none> Selector: app.kubernetes.io/name=load-balancer-example Type: LoadBalancer IP: 10.3.245.137 LoadBalancer Ingress: 104.198.205.71 Port: <unset> 8080/TCP NodePort: <unset> 32377/TCP Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more... Session Affinity: None Events: <none> Make a note of the external IP address (LoadBalancer Ingress) exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of Port and NodePort. In this example, the Port is 8080 and the NodePort is 32


Question: What are the benefits of Exposing an External IP Address to Access an Application in a Cluster?

Answer: Exposing an External IP Address to Access an Application in a ClusterThis page shows how to create a Kubernetes Service object that exposes an external IP address.Before you beginInstall kubectl.Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an external load balancer, which requires a cloud provider.Configure kubectl to communicate with your Kubernetes API server. For instructions, see the documentation for your cloud provider.ObjectivesRun five instances of a Hello World application.Create a Service object that exposes an external IP address.Use the Service object to access the running application.Creating a service for an application running in five podsRun a Hello World application in your cluster:service/load-balancer-example.yaml apiVersion: apps/v1 kind: Deployment metadata: labels: app.kubernetes.io/name: load-balancer-example name: hello-world spec: replicas: 5 selector: matchLabels: app.kubernetes.io/name: load-balancer-example template: metadata: labels: app.kubernetes.io/name: load-balancer-example spec: containers: - image: gcr.io/google-samples/hello-app:2.0 name: hello-world ports: - containerPort: 8080 kubectl apply -f https://k8s.io/examples/service/load-balancer-example.yaml The preceding command creates a Deployment and an associated ReplicaSet. The ReplicaSet has five Pods each of which runs the Hello World application.Display information about the Deployment:kubectl get deployments hello-world kubectl describe deployments hello-world Display information about your ReplicaSet objects:kubectl get replicasets kubectl describe replicasets Create a Service object that exposes the deployment:kubectl expose deployment hello-world --type=LoadBalancer --name=my-service Display information about the Service:kubectl get services my-service The output is similar to:NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service LoadBalancer 10.3.245.137 104.198.205.71 8080/TCP 54s Note:The type=LoadBalancer service is backed by external cloud providers, which is not covered in this example, please refer to this page for the details.Note:If the external IP address is shown as <pending>, wait for a minute and enter the same command again.Display detailed information about the Service:kubectl describe services my-service The output is similar to:Name: my-service Namespace: default Labels: app.kubernetes.io/name=load-balancer-example Annotations: <none> Selector: app.kubernetes.io/name=load-balancer-example Type: LoadBalancer IP: 10.3.245.137 LoadBalancer Ingress: 104.198.205.71 Port: <unset> 8080/TCP NodePort: <unset> 32377/TCP Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more... Session Affinity: None Events: <none> Make a note of the external IP address (LoadBalancer Ingress) exposed by your service. In this example, the external IP address is 104.198.205.71. Also note the value of Port and NodePort. In this example, the Port is 8080 and the NodePort is 32


Question: What is Exposing an External IP Address to Access an Application in a Cluster?

Answer: T h i s   p a g e   s h o w s   h o w   t o   c r e a t e   a   K u b e r n e t e s   S e r v i c e   o b j e c t   t h a t   e x p o s e s   a n   e x t e r n a l   I P   a d d r e s s .


Question: What is Before you begin?

Answer: I n s t a l l   k u b e c t l . U s e   a   c l o u d   p r o v i d e r   l i k e   G o o g l e   K u b e r n e t e s   E n g i n e   o r   A m a z o n   W e b   S e r v i c e s   t o   c r e a t e   a   K u b e r n e t e s   c l u s t e r .   T h i s   t u t o r i a l   c r e a t e s   a n   e x t e r n a l   l o a d   b a l a n c e r ,   w h i c h   r e q u i r e s   a   c l o u d   p r o v i d e r . C o n f i g u r e   k u b e c t l   t o   c o m m u n i c a t e   w i t h   y o u r   K u b e r n e t e s   A P I   s e r v e r .   F o r   i n s t r u c t i o n s ,   s e e   t h e   d o c u m e n t a t i o n   f o r   y o u r   c l o u d   p r o v i d e r .


Question: What is Objectives?

Answer: R u n   f i v e   i n s t a n c e s   o f   a   H e l l o   W o r l d   a p p l i c a t i o n . C r e a t e   a   S e r v i c e   o b j e c t   t h a t   e x p o s e s   a n   e x t e r n a l   I P   a d d r e s s . U s e   t h e   S e r v i c e   o b j e c t   t o   a c c e s s   t h e   r u n n i n g   a p p l i c a t i o n .


Question: What is Creating a service for an application running in five pods?

Answer: R u n   a   H e l l o   W o r l d   a p p l i c a t i o n   i n   y o u r   c l u s t e r : s e r v i c e / l o a d - b a l a n c e r - e x a m p l e . y a m l   a p i V e r s i o n :   a p p s / v 1   k i n d :   D e p l o y m e n t   m e t a d a t a :   l a b e l s :   a p p . k u b e r n e t e s . i o / n a m e :   l o a d - b a l a n c e r - e x a m p l e   n a m e :   h e l l o - w o r l d   s p e c :   r e p l i c a s :   5   s e l e c t o r :   m a t c h L a b e l s :   a p p . k u b e r n e t e s . i o / n a m e :   l o a d - b a l a n c e r - e x a m p l e   t e m p l a t e :   m e t a d a t a :   l a b e l s :   a p p . k u b e r n e t e s . i o / n a m e :   l o a d - b a l a n c e r - e x a m p l e   s p e c :   c o n t a i n e r s :   -   i m a g e :   g c r . i o / g o o g l e - s a m p l e s / h e l l o - a p p : 2 . 0   n a m e :   h e l l o - w o r l d   p o r t s :   -   c o n t a i n e r P o r t :   8 0 8 0   k u b e c t l   a p p l y   - f   h t t p s : / / k 8 s . i o / e x a m p l e s / s e r v i c e / l o a d - b a l a n c e r - e x a m p l e . y a m l   T h e   p r e c e d i n g   c o m m a n d   c r e a t e s   a   D e p l o y m e n t   a n d   a n   a s s o c i a t e d   R e p l i c a S e t .   T h e   R e p l i c a S e t   h a s   f i v e   P o d s   e a c h   o f   w h i c h   r u n s   t h e   H e l l o   W o r l d   a p p l i c a t i o n . D i s p l a y   i n f o r m a t i o n   a b o u t   t h e   D e p l o y m e n t : k u b e c t l   g e t   d e p l o y m e n t s   h e l l o - w o r l d   k u b e c t l   d e s c r i b e   d e p l o y m e n t s   h e l l o - w o r l d   D i s p l a y   i n f o r m a t i o n   a b o u t   y o u r   R e p l i c a S e t   o b j e c t s : k u b e c t l   g e t   r e p l i c a s e t s   k u b e c t l   d e s c r i b e   r e p l i c a s e t s   C r e a t e   a   S e r v i c e   o b j e c t   t h a t   e x p o s e s   t h e   d e p l o y m e n t : k u b e c t l   e x p o s e   d e p l o y m e n t   h e l l o


Question: What is Note:?

Answer: D i s p l a y   d e t a i l e d   i n f o r m a t i o n   a b o u t   t h e   S e r v i c e :   k u b e c t l   d e s c r i b e   s e r v i c e s   m y - s e r v i c e   T h e   o u t p u t   i s   s i m i l a r   t o :   N a m e :   m y - s e r v i c e   N a m e s p a c e :   d e f a u l t   L a b e l s :   a p p . k u b e r n e t e s . i o / n a m e = l o a d - b a l a n c e r - e x a m p l e   A n n o t a t i o n s :   < n o n e >   S e l e c t o r :   a p p . k u b e r n e t e s . i o / n a m e = l o a d - b a l a n c e r - e x a m p l e   T y p e :   L o a d B a l a n c e r   I P :   1 0 . 3 . 2 4 5 . 1 3 7   L o a d B a l a n c e r   I n g r e s s :   1 0 4 . 1 9 8 . 2 0 5 . 7 1   P o r t :   < u n s e t >   8 0 8 0 / T C P   N o d e P o r t :   < u n s e t >   3 2 3 7 7 / T C P   E n d p o i n t s :   1 0 . 0 . 0 . 6 : 8 0 8 0 , 1 0 . 0 . 1 . 6 : 8 0 8 0 , 1 0 . 0 . 1 . 7 : 8 0 8 0   +   2   m o r e . . .   S e s s i o n   A f f i n i t y :   N o n e   E v e n t s :   < n o n e >   M a k e   a   n o t e   o f   t h e   e x t e r n a l   I P   a d d r e s s   ( L o a d B a l a n c e r   I n g r e s s )   e x p o s e d   b y   y o u r   s e r v i c e .   I n   t h i s   e x a m p l e ,   t h e   e x t e r n a l   I P   a d d r e s s   i s   1 0 4 . 1 9 8 . 2 0 5 . 7 1 .   A l s o   n o t e   t h e   v a l u e   o f   P o r t   a n d   N o d e P o r t .   I n   t h i s   e x a m p l e ,   t h e   P o r t   i s   8 0 8 0   a n d   t h e   N o d e P o r t   i s   3 2 3 7 7 .   I n   t h e   p r e c e d i n g   o u t p u t ,   y o u   c a n   s e e   t h a t   t h e   s e r v i c e   h a s   s e v e r a l   e n d p o i n t s :   1 0 . 0 . 0 . 6 : 8 0 8 0 , 1 0 . 0 . 1 . 6 : 8 0 8 0 , 1 0 . 0 . 1 . 7 : 8 0 8 0   +   2   m o r e .   T h e s e   a r e   i n t e r n a l   a d d r e s s e s   o f   t h e   p o d s   t h a t   a r e   r u n n i n g   t h e   H e l l o   W o r l d   a p p l i c a t i o n .   T o   v e r i f y   t h e s e   a r e   p o d   a d d r e s s e


Question: What is Cleaning up?

Answer: T o   d e l e t e   t h e   S e r v i c e ,   e n t e r   t h i s   c o m m a n d :   k u b e c t l   d e l e t e   s e r v i c e s   m y - s e r v i c e   T o   d e l e t e   t h e   D e p l o y m e n t ,   t h e   R e p l i c a S e t ,   a n d   t h e   P o d s   t h a t   a r e   r u n n i n g   t h e   H e l l o   W o r l d   a p p l i c a t i o n ,   e n t e r   t h i s   c o m m a n d :   k u b e c t l   d e l e t e   d e p l o y m e n t   h e l l o - w o r l d


Question: What is What's next?

Answer: L e a r n   m o r e   a b o u t   c o n n e c t i n g   a p p l i c a t i o n s   w i t h   s e r v i c e s .


Question: What is Admission Control in Kubernetes?

Answer: Admission Control in KubernetesThis page provides an overview of admission controllers.An admission controller is a piece of code that intercepts requests to the Kubernetes API server prior to persistence of the resource, but after the request is authenticated and authorized.Several important features of Kubernetes require an admission controller to be enabled in order to properly support the feature. As a result, a Kubernetes API server that is not properly configured with the right set of admission controllers is an incomplete server that will not support all the features you expect.What are they?Admission controllers are code within the Kubernetes API server that check the data arriving in a request to modify a resource.Admission controllers apply to requests that create, delete, or modify objects. Admission controllers can also block custom verbs, such as a request to connect to a pod via an API server proxy. Admission controllers do not (and cannot) block requests to read (get, watch or list) objects, because reads bypass the admission control layer.Admission control mechanisms may be validating, mutating, or both. Mutating controllers may modify the data for the resource being modified; validating controllers may not.The admission controllers in Kubernetes 1.34 consist of the list below, are compiled into the kube-apiserver binary, and may only be configured by the cluster administrator.Admission control extension pointsWithin the full list, there are three special controllers: MutatingAdmissionWebhook, ValidatingAdmissionWebhook, and ValidatingAdmissionPolicy. The two webhook controllers execute the mutating and validating (respectively) admission control webhooks which are configured in the API. ValidatingAdmissionPolicy provides a way to embed declarative validation code within the API, without relying on any external HTTP callouts.You can use these three admission controllers to customize cluster behavior at admission time.Admission control phasesThe admission control process proceeds in two phases. In the first phase, mutating admission controllers are run. In the second phase, validating admission controllers are run. Note again that some of the controllers are both.If any of the controllers in either phase reject the request, the entire request is rejected immediately and an error is returned to the end-user.Finally, in addition to sometimes mutating the object in question, admission controllers may sometimes have side effects, that is, mutate related resources as part of request processing. Incrementing quota usage is the canonical example of why this is necessary. Any such side-effect needs a corresponding reclamation or reconciliation process, as a given admission controller does not know for sure that a given request will pass all of the other admission controllers.The ordering of these calls can be seen below.Why do I need them?Several important features of Kubernetes require an admission controller to be enabled in order to pro


Question: How does Admission Control in Kubernetes work?

Answer: Admission Control in KubernetesThis page provides an overview of admission controllers.An admission controller is a piece of code that intercepts requests to the Kubernetes API server prior to persistence of the resource, but after the request is authenticated and authorized.Several important features of Kubernetes require an admission controller to be enabled in order to properly support the feature. As a result, a Kubernetes API server that is not properly configured with the right set of admission controllers is an incomplete server that will not support all the features you expect.What are they?Admission controllers are code within the Kubernetes API server that check the data arriving in a request to modify a resource.Admission controllers apply to requests that create, delete, or modify objects. Admission controllers can also block custom verbs, such as a request to connect to a pod via an API server proxy. Admission controllers do not (and cannot) block requests to read (get, watch or list) objects, because reads bypass the admission control layer.Admission control mechanisms may be validating, mutating, or both. Mutating controllers may modify the data for the resource being modified; validating controllers may not.The admission controllers in Kubernetes 1.34 consist of the list below, are compiled into the kube-apiserver binary, and may only be configured by the cluster administrator.Admission control extension pointsWithin the full list, there are three special controllers: MutatingAdmissionWebhook, ValidatingAdmissionWebhook, and ValidatingAdmissionPolicy. The two webhook controllers execute the mutating and validating (respectively) admission control webhooks which are configured in the API. ValidatingAdmissionPolicy provides a way to embed declarative validation code within the API, without relying on any external HTTP callouts.You can use these three admission controllers to customize cluster behavior at admission time.Admission control phasesThe admission control process proceeds in two phases. In the first phase, mutating admission controllers are run. In the second phase, validating admission controllers are run. Note again that some of the controllers are both.If any of the controllers in either phase reject the request, the entire request is rejected immediately and an error is returned to the end-user.Finally, in addition to sometimes mutating the object in question, admission controllers may sometimes have side effects, that is, mutate related resources as part of request processing. Incrementing quota usage is the canonical example of why this is necessary. Any such side-effect needs a corresponding reclamation or reconciliation process, as a given admission controller does not know for sure that a given request will pass all of the other admission controllers.The ordering of these calls can be seen below.Why do I need them?Several important features of Kubernetes require an admission controller to be enabled in order to pro


Question: When would you use Admission Control in Kubernetes?

Answer: Admission Control in KubernetesThis page provides an overview of admission controllers.An admission controller is a piece of code that intercepts requests to the Kubernetes API server prior to persistence of the resource, but after the request is authenticated and authorized.Several important features of Kubernetes require an admission controller to be enabled in order to properly support the feature. As a result, a Kubernetes API server that is not properly configured with the right set of admission controllers is an incomplete server that will not support all the features you expect.What are they?Admission controllers are code within the Kubernetes API server that check the data arriving in a request to modify a resource.Admission controllers apply to requests that create, delete, or modify objects. Admission controllers can also block custom verbs, such as a request to connect to a pod via an API server proxy. Admission controllers do not (and cannot) block requests to read (get, watch or list) objects, because reads bypass the admission control layer.Admission control mechanisms may be validating, mutating, or both. Mutating controllers may modify the data for the resource being modified; validating controllers may not.The admission controllers in Kubernetes 1.34 consist of the list below, are compiled into the kube-apiserver binary, and may only be configured by the cluster administrator.Admission control extension pointsWithin the full list, there are three special controllers: MutatingAdmissionWebhook, ValidatingAdmissionWebhook, and ValidatingAdmissionPolicy. The two webhook controllers execute the mutating and validating (respectively) admission control webhooks which are configured in the API. ValidatingAdmissionPolicy provides a way to embed declarative validation code within the API, without relying on any external HTTP callouts.You can use these three admission controllers to customize cluster behavior at admission time.Admission control phasesThe admission control process proceeds in two phases. In the first phase, mutating admission controllers are run. In the second phase, validating admission controllers are run. Note again that some of the controllers are both.If any of the controllers in either phase reject the request, the entire request is rejected immediately and an error is returned to the end-user.Finally, in addition to sometimes mutating the object in question, admission controllers may sometimes have side effects, that is, mutate related resources as part of request processing. Incrementing quota usage is the canonical example of why this is necessary. Any such side-effect needs a corresponding reclamation or reconciliation process, as a given admission controller does not know for sure that a given request will pass all of the other admission controllers.The ordering of these calls can be seen below.Why do I need them?Several important features of Kubernetes require an admission controller to be enabled in order to pro


Question: What are the benefits of Admission Control in Kubernetes?

Answer: Admission Control in KubernetesThis page provides an overview of admission controllers.An admission controller is a piece of code that intercepts requests to the Kubernetes API server prior to persistence of the resource, but after the request is authenticated and authorized.Several important features of Kubernetes require an admission controller to be enabled in order to properly support the feature. As a result, a Kubernetes API server that is not properly configured with the right set of admission controllers is an incomplete server that will not support all the features you expect.What are they?Admission controllers are code within the Kubernetes API server that check the data arriving in a request to modify a resource.Admission controllers apply to requests that create, delete, or modify objects. Admission controllers can also block custom verbs, such as a request to connect to a pod via an API server proxy. Admission controllers do not (and cannot) block requests to read (get, watch or list) objects, because reads bypass the admission control layer.Admission control mechanisms may be validating, mutating, or both. Mutating controllers may modify the data for the resource being modified; validating controllers may not.The admission controllers in Kubernetes 1.34 consist of the list below, are compiled into the kube-apiserver binary, and may only be configured by the cluster administrator.Admission control extension pointsWithin the full list, there are three special controllers: MutatingAdmissionWebhook, ValidatingAdmissionWebhook, and ValidatingAdmissionPolicy. The two webhook controllers execute the mutating and validating (respectively) admission control webhooks which are configured in the API. ValidatingAdmissionPolicy provides a way to embed declarative validation code within the API, without relying on any external HTTP callouts.You can use these three admission controllers to customize cluster behavior at admission time.Admission control phasesThe admission control process proceeds in two phases. In the first phase, mutating admission controllers are run. In the second phase, validating admission controllers are run. Note again that some of the controllers are both.If any of the controllers in either phase reject the request, the entire request is rejected immediately and an error is returned to the end-user.Finally, in addition to sometimes mutating the object in question, admission controllers may sometimes have side effects, that is, mutate related resources as part of request processing. Incrementing quota usage is the canonical example of why this is necessary. Any such side-effect needs a corresponding reclamation or reconciliation process, as a given admission controller does not know for sure that a given request will pass all of the other admission controllers.The ordering of these calls can be seen below.Why do I need them?Several important features of Kubernetes require an admission controller to be enabled in order to pro


Question: What is Admission Control in Kubernetes?

Answer: T h i s   p a g e   p r o v i d e s   a n   o v e r v i e w   o f   a d m i s s i o n   c o n t r o l l e r s .   A n   a d m i s s i o n   c o n t r o l l e r   i s   a   p i e c e   o f   c o d e   t h a t   i n t e r c e p t s   r e q u e s t s   t o   t h e   K u b e r n e t e s   A P I   s e r v e r   p r i o r   t o   p e r s i s t e n c e   o f   t h e   r e s o u r c e ,   b u t   a f t e r   t h e   r e q u e s t   i s   a u t h e n t i c a t e d   a n d   a u t h o r i z e d .   S e v e r a l   i m p o r t a n t   f e a t u r e s   o f   K u b e r n e t e s   r e q u i r e   a n   a d m i s s i o n   c o n t r o l l e r   t o   b e   e n a b l e d   i n   o r d e r   t o   p r o p e r l y   s u p p o r t   t h e   f e a t u r e .   A s   a   r e s u l t ,   a   K u b e r n e t e s   A P I   s e r v e r   t h a t   i s   n o t   p r o p e r l y   c o n f i g u r e d   w i t h   t h e   r i g h t   s e t   o f   a d m i s s i o n   c o n t r o l l e r s   i s   a n   i n c o m p l e t e   s e r v e r   t h a t   w i l l   n o t   s u p p o r t   a l l   t h e   f e a t u r e s   y o u   e x p e c t .


Question: What is What are they??

Answer: A d m i s s i o n   c o n t r o l l e r s   a r e   c o d e   w i t h i n   t h e   K u b e r n e t e s   A P I   s e r v e r   t h a t   c h e c k   t h e   d a t a   a r r i v i n g   i n   a   r e q u e s t   t o   m o d i f y   a   r e s o u r c e .   A d m i s s i o n   c o n t r o l l e r s   a p p l y   t o   r e q u e s t s   t h a t   c r e a t e ,   d e l e t e ,   o r   m o d i f y   o b j e c t s .   A d m i s s i o n   c o n t r o l l e r s   c a n   a l s o   b l o c k   c u s t o m   v e r b s ,   s u c h   a s   a   r e q u e s t   t o   c o n n e c t   t o   a   p o d   v i a   a n   A P I   s e r v e r   p r o x y .   A d m i s s i o n   c o n t r o l l e r s   d o   n o t   ( a n d   c a n n o t )   b l o c k   r e q u e s t s   t o   r e a d   ( g e t ,   w a t c h   o r   l i s t )   o b j e c t s ,   b e c a u s e   r e a d s   b y p a s s   t h e   a d m i s s i o n   c o n t r o l   l a y e r .   A d m i s s i o n   c o n t r o l   m e c h a n i s m s   m a y   b e   v a l i d a t i n g ,   m u t a t i n g ,   o r   b o t h .   M u t a t i n g   c o n t r o l l e r s   m a y   m o d i f y   t h e   d a t a   f o r   t h e   r e s o u r c e   b e i n g   m o d i f i e d ;   v a l i d a t i n g   c o n t r o l l e r s   m a y   n o t .   T h e   a d m i s s i o n   c o n t r o l l e r s   i n   K u b e r n e t e s   1 . 3 4   c o n s i s t   o f   t h e   l i s t   b e l o w ,   a r e   c o m p i l e d   i n t o   t h e   k u b e - a p i s e r v e r   b i n a r y ,   a n d   m a y   o n l y   b e   c o n f i g u r e d   b y   t h e   c l u s t e r   a d m i n i s t r a t o r .


Question: What is Admission control extension points?

Answer: W i t h i n   t h e   f u l l   l i s t ,   t h e r e   a r e   t h r e e   s p e c i a l   c o n t r o l l e r s :   M u t a t i n g A d m i s s i o n W e b h o o k ,   V a l i d a t i n g A d m i s s i o n W e b h o o k ,   a n d   V a l i d a t i n g A d m i s s i o n P o l i c y .   T h e   t w o   w e b h o o k   c o n t r o l l e r s   e x e c u t e   t h e   m u t a t i n g   a n d   v a l i d a t i n g   ( r e s p e c t i v e l y )   a d m i s s i o n   c o n t r o l   w e b h o o k s   w h i c h   a r e   c o n f i g u r e d   i n   t h e   A P I .   V a l i d a t i n g A d m i s s i o n P o l i c y   p r o v i d e s   a   w a y   t o   e m b e d   d e c l a r a t i v e   v a l i d a t i o n   c o d e   w i t h i n   t h e   A P I ,   w i t h o u t   r e l y i n g   o n   a n y   e x t e r n a l   H T T P   c a l l o u t s .   Y o u   c a n   u s e   t h e s e   t h r e e   a d m i s s i o n   c o n t r o l l e r s   t o   c u s t o m i z e   c l u s t e r   b e h a v i o r   a t   a d m i s s i o n   t i m e .


Question: What is Admission control phases?

Answer: T h e   a d m i s s i o n   c o n t r o l   p r o c e s s   p r o c e e d s   i n   t w o   p h a s e s .   I n   t h e   f i r s t   p h a s e ,   m u t a t i n g   a d m i s s i o n   c o n t r o l l e r s   a r e   r u n .   I n   t h e   s e c o n d   p h a s e ,   v a l i d a t i n g   a d m i s s i o n   c o n t r o l l e r s   a r e   r u n .   N o t e   a g a i n   t h a t   s o m e   o f   t h e   c o n t r o l l e r s   a r e   b o t h .   I f   a n y   o f   t h e   c o n t r o l l e r s   i n   e i t h e r   p h a s e   r e j e c t   t h e   r e q u e s t ,   t h e   e n t i r e   r e q u e s t   i s   r e j e c t e d   i m m e d i a t e l y   a n d   a n   e r r o r   i s   r e t u r n e d   t o   t h e   e n d - u s e r .   F i n a l l y ,   i n   a d d i t i o n   t o   s o m e t i m e s   m u t a t i n g   t h e   o b j e c t   i n   q u e s t i o n ,   a d m i s s i o n   c o n t r o l l e r s   m a y   s o m e t i m e s   h a v e   s i d e   e f f e c t s ,   t h a t   i s ,   m u t a t e   r e l a t e d   r e s o u r c e s   a s   p a r t   o f   r e q u e s t   p r o c e s s i n g .   I n c r e m e n t i n g   q u o t a   u s a g e   i s   t h e   c a n o n i c a l   e x a m p l e   o f   w h y   t h i s   i s   n e c e s s a r y .   A n y   s u c h   s i d e - e f f e c t   n e e d s   a   c o r r e s p o n d i n g   r e c l a m a t i o n   o r   r e c o n c i l i a t i o n   p r o c e s s ,   a s   a   g i v e n   a d m i s s i o n   c o n t r o l l e r   d o e s   n o t   k n o w   f o r   s u r e   t h a t   a   g i v e n   r e q u e s t   w i l l   p a s s   a l l   o f   t h e   o t h e r   a d m i s s i o n   c o n t r o l l e r s .   T h e   o r d e r i n g   o f   t h e s e   c a l l s   c a n   b e   s e e n   b e l o w .


Question: What is Why do I need them??

Answer: S e v e r a l   i m p o r t a n t   f e a t u r e s   o f   K u b e r n e t e s   r e q u i r e   a n   a d m i s s i o n   c o n t r o l l e r   t o   b e   e n a b l e d   i n   o r d e r   t o   p r o p e r l y   s u p p o r t   t h e   f e a t u r e .   A s   a   r e s u l t ,   a   K u b e r n e t e s   A P I   s e r v e r   t h a t   i s   n o t   p r o p e r l y   c o n f i g u r e d   w i t h   t h e   r i g h t   s e t   o f   a d m i s s i o n   c o n t r o l l e r s   i s   a n   i n c o m p l e t e   s e r v e r   a n d   w i l l   n o t   s u p p o r t   a l l   t h e   f e a t u r e s   y o u   e x p e c t .


Question: What is How do I turn on an admission controller??

Answer: T h e   K u b e r n e t e s   A P I   s e r v e r   f l a g   e n a b l e - a d m i s s i o n - p l u g i n s   t a k e s   a   c o m m a - d e l i m i t e d   l i s t   o f   a d m i s s i o n   c o n t r o l   p l u g i n s   t o   i n v o k e   p r i o r   t o   m o d i f y i n g   o b j e c t s   i n   t h e   c l u s t e r .   F o r   e x a m p l e ,   t h e   f o l l o w i n g   c o m m a n d   l i n e   e n a b l e s   t h e   N a m e s p a c e L i f e c y c l e   a n d   t h e   L i m i t R a n g e r   a d m i s s i o n   c o n t r o l   p l u g i n s :   k u b e - a p i s e r v e r   - - e n a b l e - a d m i s s i o n - p l u g i n s = N a m e s p a c e L i f e c y c l e , L i m i t R a n g e r   . . .


Question: What is How do I turn off an admission controller??

Answer: T h e   K u b e r n e t e s   A P I   s e r v e r   f l a g   d i s a b l e - a d m i s s i o n - p l u g i n s   t a k e s   a   c o m m a - d e l i m i t e d   l i s t   o f   a d m i s s i o n   c o n t r o l   p l u g i n s   t o   b e   d i s a b l e d ,   e v e n   i f   t h e y   a r e   i n   t h e   l i s t   o f   p l u g i n s   e n a b l e d   b y   d e f a u l t .   k u b e - a p i s e r v e r   - - d i s a b l e - a d m i s s i o n - p l u g i n s = P o d N o d e S e l e c t o r , A l w a y s D e n y   . . .


Question: What is Which plugins are enabled by default??

Answer: T o   s e e   w h i c h   a d m i s s i o n   p l u g i n s   a r e   e n a b l e d :   k u b e - a p i s e r v e r   - h   |   g r e p   e n a b l e - a d m i s s i o n - p l u g i n s   I n   K u b e r n e t e s   1 . 3 4 ,   t h e   d e f a u l t   o n e s   a r e :   C e r t i f i c a t e A p p r o v a l ,   C e r t i f i c a t e S i g n i n g ,   C e r t i f i c a t e S u b j e c t R e s t r i c t i o n ,   D e f a u l t I n g r e s s C l a s s ,   D e f a u l t S t o r a g e C l a s s ,   D e f a u l t T o l e r a t i o n S e c o n d s ,   L i m i t R a n g e r ,   M u t a t i n g A d m i s s i o n W e b h o o k ,   N a m e s p a c e L i f e c y c l e ,   P e r s i s t e n t V o l u m e C l a i m R e s i z e ,   P o d S e c u r i t y ,   P r i o r i t y ,   R e s o u r c e Q u o t a ,   R u n t i m e C l a s s ,   S e r v i c e A c c o u n t ,   S t o r a g e O b j e c t I n U s e P r o t e c t i o n ,   T a i n t N o d e s B y C o n d i t i o n ,   V a l i d a t i n g A d m i s s i o n P o l i c y ,   V a l i d a t i n g A d m i s s i o n W e b h o o k


Question: What is AlwaysAdmit?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   a l l o w s   a l l   p o d s   i n t o   t h e   c l u s t e r .   I t   i s   d e p r e c a t e d   b e c a u s e   i t s   b e h a v i o r   i s   t h e   s a m e   a s   i f   t h e r e   w e r e   n o   a d m i s s i o n   c o n t r o l l e r   a t   a l l .


Question: What is AlwaysDeny?

Answer: T y p e :   V a l i d a t i n g .   R e j e c t s   a l l   r e q u e s t s .   A l w a y s D e n y   i s   d e p r e c a t e d   a s   i t   h a s   n o   r e a l   m e a n i n g .


Question: What is AlwaysPullImages?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   m o d i f i e s   e v e r y   n e w   P o d   t o   f o r c e   t h e   i m a g e   p u l l   p o l i c y   t o   A l w a y s .   T h i s   i s   u s e f u l   i n   a   m u l t i t e n a n t   c l u s t e r   s o   t h a t   u s e r s   c a n   b e   a s s u r e d   t h a t   t h e i r   p r i v a t e   i m a g e s   c a n   o n l y   b e   u s e d   b y   t h o s e   w h o   h a v e   t h e   c r e d e n t i a l s   t o   p u l l   t h e m .   W i t h o u t   t h i s   a d m i s s i o n   c o n t r o l l e r ,   o n c e   a n   i m a g e   h a s   b e e n   p u l l e d   t o   a   n o d e ,   a n y   p o d   f r o m   a n y   u s e r   c a n   u s e   i t   b y   k n o w i n g   t h e   i m a g e ' s   n a m e   ( a s s u m i n g   t h e   P o d   i s   s c h e d u l e d   o n t o   t h e   r i g h t   n o d e ) ,   w i t h o u t   a n y   a u t h o r i z a t i o n   c h e c k   a g a i n s t   t h e   i m a g e .   W h e n   t h i s   a d m i s s i o n   c o n t r o l l e r   i s   e n a b l e d ,   i m a g e s   a r e   a l w a y s   p u l l e d   p r i o r   t o   s t a r t i n g   c o n t a i n e r s ,   w h i c h   m e a n s   v a l i d   c r e d e n t i a l s   a r e   r e q u i r e d .


Question: What is CertificateApproval?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   o b s e r v e s   r e q u e s t s   t o   a p p r o v e   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e s   a n d   p e r f o r m s   a d d i t i o n a l   a u t h o r i z a t i o n   c h e c k s   t o   e n s u r e   t h e   a p p r o v i n g   u s e r   h a s   p e r m i s s i o n   t o   a p p r o v e   c e r t i f i c a t e   r e q u e s t s   w i t h   t h e   s p e c . s i g n e r N a m e   r e q u e s t e d   o n   t h e   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e .   S e e   C e r t i f i c a t e   S i g n i n g   R e q u e s t s   f o r   m o r e   i n f o r m a t i o n   o n   t h e   p e r m i s s i o n s   r e q u i r e d   t o   p e r f o r m   d i f f e r e n t   a c t i o n s   o n   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e s .


Question: What is CertificateSigning?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   o b s e r v e s   u p d a t e s   t o   t h e   s t a t u s . c e r t i f i c a t e   f i e l d   o f   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e s   a n d   p e r f o r m s   a n   a d d i t i o n a l   a u t h o r i z a t i o n   c h e c k s   t o   e n s u r e   t h e   s i g n i n g   u s e r   h a s   p e r m i s s i o n   t o   s i g n   c e r t i f i c a t e   r e q u e s t s   w i t h   t h e   s p e c . s i g n e r N a m e   r e q u e s t e d   o n   t h e   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e .   S e e   C e r t i f i c a t e   S i g n i n g   R e q u e s t s   f o r   m o r e   i n f o r m a t i o n   o n   t h e   p e r m i s s i o n s   r e q u i r e d   t o   p e r f o r m   d i f f e r e n t   a c t i o n s   o n   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e s .


Question: What is CertificateSubjectRestriction?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   o b s e r v e s   c r e a t i o n   o f   C e r t i f i c a t e S i g n i n g R e q u e s t   r e s o u r c e s   t h a t   h a v e   a   s p e c . s i g n e r N a m e   o f   k u b e r n e t e s . i o / k u b e - a p i s e r v e r - c l i e n t .   I t   r e j e c t s   a n y   r e q u e s t   t h a t   s p e c i f i e s   a   ' g r o u p '   ( o r   ' o r g a n i z a t i o n   a t t r i b u t e ' )   o f   s y s t e m : m a s t e r s .


Question: What is DefaultIngressClass?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   o b s e r v e s   c r e a t i o n   o f   I n g r e s s   o b j e c t s   t h a t   d o   n o t   r e q u e s t   a n y   s p e c i f i c   i n g r e s s   c l a s s   a n d   a u t o m a t i c a l l y   a d d s   a   d e f a u l t   i n g r e s s   c l a s s   t o   t h e m .   T h i s   w a y ,   u s e r s   t h a t   d o   n o t   r e q u e s t   a n y   s p e c i a l   i n g r e s s   c l a s s   d o   n o t   n e e d   t o   c a r e   a b o u t   t h e m   a t   a l l   a n d   t h e y   w i l l   g e t   t h e   d e f a u l t   o n e .   T h i s   a d m i s s i o n   c o n t r o l l e r   d o e s   n o t   d o   a n y t h i n g   w h e n   n o   d e f a u l t   i n g r e s s   c l a s s   i s   c o n f i g u r e d .   W h e n   m o r e   t h a n   o n e   i n g r e s s   c l a s s   i s   m a r k e d   a s   d e f a u l t ,   i t   r e j e c t s   a n y   c r e a t i o n   o f   I n g r e s s   w i t h   a n   e r r o r   a n d   a n   a d m i n i s t r a t o r   m u s t   r e v i s i t   t h e i r   I n g r e s s C l a s s   o b j e c t s   a n d   m a r k   o n l y   o n e   a s   d e f a u l t   ( w i t h   t h e   a n n o t a t i o n   " i n g r e s s c l a s s . k u b e r n e t e s . i o / i s - d e f a u l t - c l a s s " ) .   T h i s   a d m i s s i o n   c o n t r o l l e r   i g n o r e s   a n y   I n g r e s s   u p d a t e s ;   i t   a c t s   o n l y   o n   c r e a t i o n .   S e e   t h e   I n g r e s s   d o c u m e n t a t i o n   f o r   m o r e   a b o u t   i n g r e s s   c l a s s e s   a n d   h o w   t o   m a r k   o n e   a s   d e f a u l t .


Question: What is DefaultStorageClass?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   o b s e r v e s   c r e a t i o n   o f   P e r s i s t e n t V o l u m e C l a i m   o b j e c t s   t h a t   d o   n o t   r e q u e s t   a n y   s p e c i f i c   s t o r a g e   c l a s s   a n d   a u t o m a t i c a l l y   a d d s   a   d e f a u l t   s t o r a g e   c l a s s   t o   t h e m .   T h i s   w a y ,   u s e r s   t h a t   d o   n o t   r e q u e s t   a n y   s p e c i a l   s t o r a g e   c l a s s   d o   n o t   n e e d   t o   c a r e   a b o u t   t h e m   a t   a l l   a n d   t h e y   w i l l   g e t   t h e   d e f a u l t   o n e .   T h i s   a d m i s s i o n   c o n t r o l l e r   d o e s   n o t h i n g   w h e n   n o   d e f a u l t   S t o r a g e C l a s s   e x i s t s .   W h e n   m o r e   t h a n   o n e   s t o r a g e   c l a s s   i s   m a r k e d   a s   d e f a u l t ,   a n d   y o u   t h e n   c r e a t e   a   P e r s i s t e n t V o l u m e C l a i m   w i t h   n o   s t o r a g e C l a s s N a m e   s e t ,   K u b e r n e t e s   u s e s   t h e   m o s t   r e c e n t l y   c r e a t e d   d e f a u l t   S t o r a g e C l a s s .   W h e n   a   P e r s i s t e n t V o l u m e C l a i m   i s   c r e a t e d   w i t h   a   s p e c i f i e d   v o l u m e N a m e ,   i t   r e m a i n s   i n   a   p e n d i n g   s t a t e   i f   t h e   s t a t i c   v o l u m e ' s   s t o r a g e C l a s s N a m e   d o e s   n o t   m a t c h   t h e   s t o r a g e C l a s s N a m e   o n   t h e   P e r s i s t e n t V o l u m e C l a i m   a f t e r   a n y   d e f a u l t   S t o r a g e C l a s s   i s   a p p l i e d   t o   i t .   T h i s   a d m i s s i o n   c o n t r o l l e r   i g n o r e s   a n y   P e r s i s t e n t V o l u m e C l a i m   u p d a t e s ;   i t   a c t s   o n l y   o n   c r e a t i o n .   S e e   p e r s i s t e n t   v o l u m e   d o c u m e n t a t i o n   a b o u t   p e r s i s t e n t


Question: What is DefaultTolerationSeconds?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   s e t s   t h e   d e f a u l t   f o r g i v e n e s s   t o l e r a t i o n   f o r   p o d s   t o   t o l e r a t e   t h e   t a i n t s   n o t r e a d y : N o E x e c u t e   a n d   u n r e a c h a b l e : N o E x e c u t e   b a s e d   o n   t h e   k 8 s - a p i s e r v e r   i n p u t   p a r a m e t e r s   d e f a u l t - n o t - r e a d y - t o l e r a t i o n - s e c o n d s   a n d   d e f a u l t - u n r e a c h a b l e - t o l e r a t i o n - s e c o n d s   i f   t h e   p o d s   d o n ' t   a l r e a d y   h a v e   t o l e r a t i o n   f o r   t a i n t s   n o d e . k u b e r n e t e s . i o / n o t - r e a d y : N o E x e c u t e   o r   n o d e . k u b e r n e t e s . i o / u n r e a c h a b l e : N o E x e c u t e .   T h e   d e f a u l t   v a l u e   f o r   d e f a u l t - n o t - r e a d y - t o l e r a t i o n - s e c o n d s   a n d   d e f a u l t - u n r e a c h a b l e - t o l e r a t i o n - s e c o n d s   i s   5   m i n u t e s .


Question: What is DenyServiceExternalIPs?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   r e j e c t s   a l l   n e t - n e w   u s a g e   o f   t h e   S e r v i c e   f i e l d   e x t e r n a l I P s .   T h i s   f e a t u r e   i s   v e r y   p o w e r f u l   ( a l l o w s   n e t w o r k   t r a f f i c   i n t e r c e p t i o n )   a n d   n o t   w e l l   c o n t r o l l e d   b y   p o l i c y .   W h e n   e n a b l e d ,   u s e r s   o f   t h e   c l u s t e r   m a y   n o t   c r e a t e   n e w   S e r v i c e s   w h i c h   u s e   e x t e r n a l I P s   a n d   m a y   n o t   a d d   n e w   v a l u e s   t o   e x t e r n a l I P s   o n   e x i s t i n g   S e r v i c e   o b j e c t s .   E x i s t i n g   u s e s   o f   e x t e r n a l I P s   a r e   n o t   a f f e c t e d ,   a n d   u s e r s   m a y   r e m o v e   v a l u e s   f r o m   e x t e r n a l I P s   o n   e x i s t i n g   S e r v i c e   o b j e c t s .   M o s t   u s e r s   d o   n o t   n e e d   t h i s   f e a t u r e   a t   a l l ,   a n d   c l u s t e r   a d m i n s   s h o u l d   c o n s i d e r   d i s a b l i n g   i t .   C l u s t e r s   t h a t   d o   n e e d   t o   u s e   t h i s   f e a t u r e   s h o u l d   c o n s i d e r   u s i n g   s o m e   c u s t o m   p o l i c y   t o   m a n a g e   u s a g e   o f   i t .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   d i s a b l e d   b y   d e f a u l t .


Question: What is EventRateLimit?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   m i t i g a t e s   t h e   p r o b l e m   w h e r e   t h e   A P I   s e r v e r   g e t s   f l o o d e d   b y   r e q u e s t s   t o   s t o r e   n e w   E v e n t s .   T h e   c l u s t e r   a d m i n   c a n   s p e c i f y   e v e n t   r a t e   l i m i t s   b y :   E n a b l i n g   t h e   E v e n t R a t e L i m i t   a d m i s s i o n   c o n t r o l l e r ; R e f e r e n c i n g   a n   E v e n t R a t e L i m i t   c o n f i g u r a t i o n   f i l e   f r o m   t h e   f i l e   p r o v i d e d   t o   t h e   A P I   s e r v e r ' s   c o m m a n d   l i n e   f l a g   - - a d m i s s i o n - c o n t r o l - c o n f i g - f i l e :   a p i V e r s i o n :   a p i s e r v e r . c o n f i g . k 8 s . i o / v 1   k i n d :   A d m i s s i o n C o n f i g u r a t i o n   p l u g i n s :   -   n a m e :   E v e n t R a t e L i m i t   p a t h :   e v e n t c o n f i g . y a m l   . . .   T h e r e   a r e   f o u r   t y p e s   o f   l i m i t s   t h a t   c a n   b e   s p e c i f i e d   i n   t h e   c o n f i g u r a t i o n :   S e r v e r :   A l l   E v e n t   r e q u e s t s   ( c r e a t i o n   o r   m o d i f i c a t i o n s )   r e c e i v e d   b y   t h e   A P I   s e r v e r   s h a r e   a   s i n g l e   b u c k e t . N a m e s p a c e :   E a c h   n a m e s p a c e   h a s   a   d e d i c a t e d   b u c k e t . U s e r :   E a c h   u s e r   i s   a l l o c a t e d   a   b u c k e t . S o u r c e A n d O b j e c t :   A   b u c k e t   i s   a s s i g n e d   b y   e a c h   c o m b i n a t i o n   o f   s o u r c e   a n d   i n v o l v e d   o b j e c t   o f   t h e   e v e n t .   B e l o w   i s   a   s a m p l e   e v e n t c o n f i g . y a m l   f o r   s u c h   a   c o n f i g u r a t i o n :   a p i V e r s i o n :   e v e n t r a t e l i m i t . a d m i s s i o n . k 8 s . i o / v 1 a l p h a 1   k i n d :   C o n f i g u r


Question: What is ExtendedResourceToleration?

Answer: T y p e :   M u t a t i n g .   T h i s   p l u g - i n   f a c i l i t a t e s   c r e a t i o n   o f   d e d i c a t e d   n o d e s   w i t h   e x t e n d e d   r e s o u r c e s .   I f   o p e r a t o r s   w a n t   t o   c r e a t e   d e d i c a t e d   n o d e s   w i t h   e x t e n d e d   r e s o u r c e s   ( l i k e   G P U s ,   F P G A s   e t c . ) ,   t h e y   a r e   e x p e c t e d   t o   t a i n t   t h e   n o d e   w i t h   t h e   e x t e n d e d   r e s o u r c e   n a m e   a s   t h e   k e y .   T h i s   a d m i s s i o n   c o n t r o l l e r ,   i f   e n a b l e d ,   a u t o m a t i c a l l y   a d d s   t o l e r a t i o n s   f o r   s u c h   t a i n t s   t o   p o d s   r e q u e s t i n g   e x t e n d e d   r e s o u r c e s ,   s o   u s e r s   d o n ' t   h a v e   t o   m a n u a l l y   a d d   t h e s e   t o l e r a t i o n s .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   d i s a b l e d   b y   d e f a u l t .


Question: What is ImagePolicyWebhook?

Answer: T y p e :   V a l i d a t i n g .   T h e   I m a g e P o l i c y W e b h o o k   a d m i s s i o n   c o n t r o l l e r   a l l o w s   a   b a c k e n d   w e b h o o k   t o   m a k e   a d m i s s i o n   d e c i s i o n s .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   d i s a b l e d   b y   d e f a u l t .


Question: What is Configuration file format?

Answer: I m a g e P o l i c y W e b h o o k   u s e s   a   c o n f i g u r a t i o n   f i l e   t o   s e t   o p t i o n s   f o r   t h e   b e h a v i o r   o f   t h e   b a c k e n d .   T h i s   f i l e   m a y   b e   j s o n   o r   y a m l   a n d   h a s   t h e   f o l l o w i n g   f o r m a t :   i m a g e P o l i c y :   k u b e C o n f i g F i l e :   / p a t h / t o / k u b e c o n f i g / f o r / b a c k e n d   #   t i m e   i n   s   t o   c a c h e   a p p r o v a l   a l l o w T T L :   5 0   #   t i m e   i n   s   t o   c a c h e   d e n i a l   d e n y T T L :   5 0   #   t i m e   i n   m s   t o   w a i t   b e t w e e n   r e t r i e s   r e t r y B a c k o f f :   5 0 0   #   d e t e r m i n e s   b e h a v i o r   i f   t h e   w e b h o o k   b a c k e n d   f a i l s   d e f a u l t A l l o w :   t r u e   R e f e r e n c e   t h e   I m a g e P o l i c y W e b h o o k   c o n f i g u r a t i o n   f i l e   f r o m   t h e   f i l e   p r o v i d e d   t o   t h e   A P I   s e r v e r ' s   c o m m a n d   l i n e   f l a g   - - a d m i s s i o n - c o n t r o l - c o n f i g - f i l e :   a p i V e r s i o n :   a p i s e r v e r . c o n f i g . k 8 s . i o / v 1   k i n d :   A d m i s s i o n C o n f i g u r a t i o n   p l u g i n s :   -   n a m e :   I m a g e P o l i c y W e b h o o k   p a t h :   i m a g e p o l i c y c o n f i g . y a m l   . . .   A l t e r n a t i v e l y ,   y o u   c a n   e m b e d   t h e   c o n f i g u r a t i o n   d i r e c t l y   i n   t h e   f i l e :   a p i V e r s i o n :   a p i s e r v e r . c o n f i g . k 8 s . i o / v 1   k i n d :   A d m i s s i o n C o n f i g u r a t i o n   p l u g i n s :   -   n a m e :   I m a g e P o l i c y W e b h o o k   c o n f i g u r a t i o n :   i m a g e P o l i c y :   k u b e C o n f i g F i l e :   < p a t h - t o - k u b e c o n f i g - f i l e >   a l l o w T T L :   5 0   d e n y T T L :   5 0   r e t r y B a c k o f f :   5 0 0   d e f a u l t A l


Question: What is Request payloads?

Answer: W h e n   f a c e d   w i t h   a n   a d m i s s i o n   d e c i s i o n ,   t h e   A P I   S e r v e r   P O S T s   a   J S O N   s e r i a l i z e d   i m a g e p o l i c y . k 8 s . i o / v 1 a l p h a 1   I m a g e R e v i e w   o b j e c t   d e s c r i b i n g   t h e   a c t i o n .   T h i s   o b j e c t   c o n t a i n s   f i e l d s   d e s c r i b i n g   t h e   c o n t a i n e r s   b e i n g   a d m i t t e d ,   a s   w e l l   a s   a n y   p o d   a n n o t a t i o n s   t h a t   m a t c h   * . i m a g e - p o l i c y . k 8 s . i o / * .


Question: What is Note:?

Answer: A n   e x a m p l e   r e q u e s t   b o d y :   {   " a p i V e r s i o n " :   " i m a g e p o l i c y . k 8 s . i o / v 1 a l p h a 1 " ,   " k i n d " :   " I m a g e R e v i e w " ,   " s p e c " :   {   " c o n t a i n e r s " :   [   {   " i m a g e " :   " m y r e p o / m y i m a g e : v 1 "   } ,   {   " i m a g e " :   " m y r e p o / m y i m a g e @ s h a 2 5 6 : b e b 6 b d 6 a 6 8 f 1 1 4 c 1 d c 2 e a 4 b 2 8 d b 8 1 b d f 9 1 d e 2 0 2 a 9 0 1 4 9 7 2 b e c 5 e 4 d 9 1 7 1 d 9 0 e d "   }   ] ,   " a n n o t a t i o n s " :   {   " m y c l u s t e r . i m a g e - p o l i c y . k 8 s . i o / t i c k e t - 1 2 3 4 " :   " b r e a k - g l a s s "   } ,   " n a m e s p a c e " :   " m y n a m e s p a c e "   }   }   T h e   r e m o t e   s e r v i c e   i s   e x p e c t e d   t o   f i l l   t h e   s t a t u s   f i e l d   o f   t h e   r e q u e s t   a n d   r e s p o n d   t o   e i t h e r   a l l o w   o r   d i s a l l o w   a c c e s s .   T h e   r e s p o n s e   b o d y ' s   s p e c   f i e l d   i s   i g n o r e d ,   a n d   m a y   b e   o m i t t e d .   A   p e r m i s s i v e   r e s p o n s e   w o u l d   r e t u r n :   {   " a p i V e r s i o n " :   " i m a g e p o l i c y . k 8 s . i o / v 1 a l p h a 1 " ,   " k i n d " :   " I m a g e R e v i e w " ,   " s t a t u s " :   {   " a l l o w e d " :   t r u e   }   }   T o   d i s a l l o w   a c c e s s ,   t h e   s e r v i c e   w o u l d   r e t u r n :   {   " a p i V e r s i o n " :   " i m a g e p o l i c y . k 8 s . i o / v 1 a l p h a 1 " ,   " k i n d " :   " I m a g e R e v i e w " ,   " s t a t u s " :   {   " a l l o w e d " :   f a l s e ,   " r e a s o n " :   " i m a g e   c u r r e n t l y   b l a c k l i s t e d "   }   }   F o r   f u r t h e r   d o c u m e n t a t i o n   r e f e r   t o   t h e   i m a g e p o l i c y . v 1 a l p h a 1   A P I .


Question: What is Extending with Annotations?

Answer: A l l   a n n o t a t i o n s   o n   a   P o d   t h a t   m a t c h   * . i m a g e - p o l i c y . k 8 s . i o / *   a r e   s e n t   t o   t h e   w e b h o o k .   S e n d i n g   a n n o t a t i o n s   a l l o w s   u s e r s   w h o   a r e   a w a r e   o f   t h e   i m a g e   p o l i c y   b a c k e n d   t o   s e n d   e x t r a   i n f o r m a t i o n   t o   i t ,   a n d   f o r   d i f f e r e n t   b a c k e n d s   i m p l e m e n t a t i o n s   t o   a c c e p t   d i f f e r e n t   i n f o r m a t i o n .   E x a m p l e s   o f   i n f o r m a t i o n   y o u   m i g h t   p u t   h e r e   a r e :   r e q u e s t   t o   " b r e a k   g l a s s "   t o   o v e r r i d e   a   p o l i c y ,   i n   c a s e   o f   e m e r g e n c y . a   t i c k e t   n u m b e r   f r o m   a   t i c k e t   s y s t e m   t h a t   d o c u m e n t s   t h e   b r e a k - g l a s s   r e q u e s t p r o v i d e   a   h i n t   t o   t h e   p o l i c y   s e r v e r   a s   t o   t h e   i m a g e I D   o f   t h e   i m a g e   b e i n g   p r o v i d e d ,   t o   s a v e   i t   a   l o o k u p   I n   a n y   c a s e ,   t h e   a n n o t a t i o n s   a r e   p r o v i d e d   b y   t h e   u s e r   a n d   a r e   n o t   v a l i d a t e d   b y   K u b e r n e t e s   i n   a n y   w a y .


Question: What is LimitPodHardAntiAffinityTopology?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   d e n i e s   a n y   p o d   t h a t   d e f i n e s   A n t i A f f i n i t y   t o p o l o g y   k e y   o t h e r   t h a n   k u b e r n e t e s . i o / h o s t n a m e   i n   r e q u i r e d D u r i n g S c h e d u l i n g R e q u i r e d D u r i n g E x e c u t i o n .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   d i s a b l e d   b y   d e f a u l t .


Question: What is LimitRanger?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   w i l l   o b s e r v e   t h e   i n c o m i n g   r e q u e s t   a n d   e n s u r e   t h a t   i t   d o e s   n o t   v i o l a t e   a n y   o f   t h e   c o n s t r a i n t s   e n u m e r a t e d   i n   t h e   L i m i t R a n g e   o b j e c t   i n   a   N a m e s p a c e .   I f   y o u   a r e   u s i n g   L i m i t R a n g e   o b j e c t s   i n   y o u r   K u b e r n e t e s   d e p l o y m e n t ,   y o u   M U S T   u s e   t h i s   a d m i s s i o n   c o n t r o l l e r   t o   e n f o r c e   t h o s e   c o n s t r a i n t s .   L i m i t R a n g e r   c a n   a l s o   b e   u s e d   t o   a p p l y   d e f a u l t   r e s o u r c e   r e q u e s t s   t o   P o d s   t h a t   d o n ' t   s p e c i f y   a n y ;   c u r r e n t l y ,   t h e   d e f a u l t   L i m i t R a n g e r   a p p l i e s   a   0 . 1   C P U   r e q u i r e m e n t   t o   a l l   P o d s   i n   t h e   d e f a u l t   n a m e s p a c e .   S e e   t h e   L i m i t R a n g e   A P I   r e f e r e n c e   a n d   t h e   e x a m p l e   o f   L i m i t R a n g e   f o r   m o r e   d e t a i l s .


Question: What is MutatingAdmissionWebhook?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   c a l l s   a n y   m u t a t i n g   w e b h o o k s   w h i c h   m a t c h   t h e   r e q u e s t .   M a t c h i n g   w e b h o o k s   a r e   c a l l e d   i n   s e r i a l ;   e a c h   o n e   m a y   m o d i f y   t h e   o b j e c t   i f   i t   d e s i r e s .   T h i s   a d m i s s i o n   c o n t r o l l e r   ( a s   i m p l i e d   b y   t h e   n a m e )   o n l y   r u n s   i n   t h e   m u t a t i n g   p h a s e .   I f   a   w e b h o o k   c a l l e d   b y   t h i s   h a s   s i d e   e f f e c t s   ( f o r   e x a m p l e ,   d e c r e m e n t i n g   q u o t a )   i t   m u s t   h a v e   a   r e c o n c i l i a t i o n   s y s t e m ,   a s   i t   i s   n o t   g u a r a n t e e d   t h a t   s u b s e q u e n t   w e b h o o k s   o r   v a l i d a t i n g   a d m i s s i o n   c o n t r o l l e r s   w i l l   p e r m i t   t h e   r e q u e s t   t o   f i n i s h .   I f   y o u   d i s a b l e   t h e   M u t a t i n g A d m i s s i o n W e b h o o k ,   y o u   m u s t   a l s o   d i s a b l e   t h e   M u t a t i n g W e b h o o k C o n f i g u r a t i o n   o b j e c t   i n   t h e   a d m i s s i o n r e g i s t r a t i o n . k 8 s . i o / v 1   g r o u p / v e r s i o n   v i a   t h e   - - r u n t i m e - c o n f i g   f l a g ,   b o t h   a r e   o n   b y   d e f a u l t .


Question: What is Use caution when authoring and installing mutating webhooks?

Answer: U s e r s   m a y   b e   c o n f u s e d   w h e n   t h e   o b j e c t s   t h e y   t r y   t o   c r e a t e   a r e   d i f f e r e n t   f r o m   w h a t   t h e y   g e t   b a c k . B u i l t   i n   c o n t r o l   l o o p s   m a y   b r e a k   w h e n   t h e   o b j e c t s   t h e y   t r y   t o   c r e a t e   a r e   d i f f e r e n t   w h e n   r e a d   b a c k . S e t t i n g   o r i g i n a l l y   u n s e t   f i e l d s   i s   l e s s   l i k e l y   t o   c a u s e   p r o b l e m s   t h a n   o v e r w r i t i n g   f i e l d s   s e t   i n   t h e   o r i g i n a l   r e q u e s t .   A v o i d   d o i n g   t h e   l a t t e r . F u t u r e   c h a n g e s   t o   c o n t r o l   l o o p s   f o r   b u i l t - i n   r e s o u r c e s   o r   t h i r d - p a r t y   r e s o u r c e s   m a y   b r e a k   w e b h o o k s   t h a t   w o r k   w e l l   t o d a y .   E v e n   w h e n   t h e   w e b h o o k   i n s t a l l a t i o n   A P I   i s   f i n a l i z e d ,   n o t   a l l   p o s s i b l e   w e b h o o k   b e h a v i o r s   w i l l   b e   g u a r a n t e e d   t o   b e   s u p p o r t e d   i n d e f i n i t e l y .   S e t t i n g   o r i g i n a l l y   u n s e t   f i e l d s   i s   l e s s   l i k e l y   t o   c a u s e   p r o b l e m s   t h a n   o v e r w r i t i n g   f i e l d s   s e t   i n   t h e   o r i g i n a l   r e q u e s t .   A v o i d   d o i n g   t h e   l a t t e r .


Question: What is NamespaceAutoProvision?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   e x a m i n e s   a l l   i n c o m i n g   r e q u e s t s   o n   n a m e s p a c e d   r e s o u r c e s   a n d   c h e c k s   i f   t h e   r e f e r e n c e d   n a m e s p a c e   d o e s   e x i s t .   I t   c r e a t e s   a   n a m e s p a c e   i f   i t   c a n n o t   b e   f o u n d .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   u s e f u l   i n   d e p l o y m e n t s   t h a t   d o   n o t   w a n t   t o   r e s t r i c t   c r e a t i o n   o f   a   n a m e s p a c e   p r i o r   t o   i t s   u s a g e .


Question: What is NamespaceExists?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   c h e c k s   a l l   r e q u e s t s   o n   n a m e s p a c e d   r e s o u r c e s   o t h e r   t h a n   N a m e s p a c e   i t s e l f .   I f   t h e   n a m e s p a c e   r e f e r e n c e d   f r o m   a   r e q u e s t   d o e s n ' t   e x i s t ,   t h e   r e q u e s t   i s   r e j e c t e d .


Question: What is NamespaceLifecycle?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   e n f o r c e s   t h a t   a   N a m e s p a c e   t h a t   i s   u n d e r g o i n g   t e r m i n a t i o n   c a n n o t   h a v e   n e w   o b j e c t s   c r e a t e d   i n   i t ,   a n d   e n s u r e s   t h a t   r e q u e s t s   i n   a   n o n - e x i s t e n t   N a m e s p a c e   a r e   r e j e c t e d .   T h i s   a d m i s s i o n   c o n t r o l l e r   a l s o   p r e v e n t s   d e l e t i o n   o f   t h r e e   s y s t e m   r e s e r v e d   n a m e s p a c e s   d e f a u l t ,   k u b e - s y s t e m ,   k u b e - p u b l i c .   A   N a m e s p a c e   d e l e t i o n   k i c k s   o f f   a   s e q u e n c e   o f   o p e r a t i o n s   t h a t   r e m o v e   a l l   o b j e c t s   ( p o d s ,   s e r v i c e s ,   e t c . )   i n   t h a t   n a m e s p a c e .   I n   o r d e r   t o   e n f o r c e   i n t e g r i t y   o f   t h a t   p r o c e s s ,   w e   s t r o n g l y   r e c o m m e n d   r u n n i n g   t h i s   a d m i s s i o n   c o n t r o l l e r .


Question: What is NodeRestriction?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   l i m i t s   t h e   N o d e   a n d   P o d   o b j e c t s   a   k u b e l e t   c a n   m o d i f y .   I n   o r d e r   t o   b e   l i m i t e d   b y   t h i s   a d m i s s i o n   c o n t r o l l e r ,   k u b e l e t s   m u s t   u s e   c r e d e n t i a l s   i n   t h e   s y s t e m : n o d e s   g r o u p ,   w i t h   a   u s e r n a m e   i n   t h e   f o r m   s y s t e m : n o d e : < n o d e N a m e > .   S u c h   k u b e l e t s   w i l l   o n l y   b e   a l l o w e d   t o   m o d i f y   t h e i r   o w n   N o d e   A P I   o b j e c t ,   a n d   o n l y   m o d i f y   P o d   A P I   o b j e c t s   t h a t   a r e   b o u n d   t o   t h e i r   n o d e .   k u b e l e t s   a r e   n o t   a l l o w e d   t o   u p d a t e   o r   r e m o v e   t a i n t s   f r o m   t h e i r   N o d e   A P I   o b j e c t .   T h e   N o d e R e s t r i c t i o n   a d m i s s i o n   p l u g i n   p r e v e n t s   k u b e l e t s   f r o m   d e l e t i n g   t h e i r   N o d e   A P I   o b j e c t ,   a n d   e n f o r c e s   k u b e l e t   m o d i f i c a t i o n   o f   l a b e l s   u n d e r   t h e   k u b e r n e t e s . i o /   o r   k 8 s . i o /   p r e f i x e s   a s   f o l l o w s :   P r e v e n t s   k u b e l e t s   f r o m   a d d i n g / r e m o v i n g / u p d a t i n g   l a b e l s   w i t h   a   n o d e - r e s t r i c t i o n . k u b e r n e t e s . i o /   p r e f i x .   T h i s   l a b e l   p r e f i x   i s   r e s e r v e d   f o r   a d m i n i s t r a t o r s   t o   l a b e l   t h e i r   N o d e   o b j e c t s   f o r   w o r k l o a d   i s o l a t i o n   p u r p o s e s ,   a n d   k u b e l e t s   w i l l   n o t   b e   a l l o w e d   t o   m o d i f y   l a b e l s   w i t h   t h a t   p r e f i x . A l l o w s   k u b e l e t s   t o   a d d / r e m o v e / u p d a t e   t h e s e   l a b e l s   a n d


Question: What is OwnerReferencesPermissionEnforcement?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   p r o t e c t s   t h e   a c c e s s   t o   t h e   m e t a d a t a . o w n e r R e f e r e n c e s   o f   a n   o b j e c t   s o   t h a t   o n l y   u s e r s   w i t h   d e l e t e   p e r m i s s i o n   t o   t h e   o b j e c t   c a n   c h a n g e   i t .   T h i s   a d m i s s i o n   c o n t r o l l e r   a l s o   p r o t e c t s   t h e   a c c e s s   t o   m e t a d a t a . o w n e r R e f e r e n c e s [ x ] . b l o c k O w n e r D e l e t i o n   o f   a n   o b j e c t ,   s o   t h a t   o n l y   u s e r s   w i t h   u p d a t e   p e r m i s s i o n   t o   t h e   f i n a l i z e r s   s u b r e s o u r c e   o f   t h e   r e f e r e n c e d   o w n e r   c a n   c h a n g e   i t .


Question: What is PersistentVolumeClaimResize?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   i m p l e m e n t s   a d d i t i o n a l   v a l i d a t i o n s   f o r   c h e c k i n g   i n c o m i n g   P e r s i s t e n t V o l u m e C l a i m   r e s i z e   r e q u e s t s .   E n a b l i n g   t h e   P e r s i s t e n t V o l u m e C l a i m R e s i z e   a d m i s s i o n   c o n t r o l l e r   i s   r e c o m m e n d e d .   T h i s   a d m i s s i o n   c o n t r o l l e r   p r e v e n t s   r e s i z i n g   o f   a l l   c l a i m s   b y   d e f a u l t   u n l e s s   a   c l a i m ' s   S t o r a g e C l a s s   e x p l i c i t l y   e n a b l e s   r e s i z i n g   b y   s e t t i n g   a l l o w V o l u m e E x p a n s i o n   t o   t r u e .   F o r   e x a m p l e :   a l l   P e r s i s t e n t V o l u m e C l a i m s   c r e a t e d   f r o m   t h e   f o l l o w i n g   S t o r a g e C l a s s   s u p p o r t   v o l u m e   e x p a n s i o n :   a p i V e r s i o n :   s t o r a g e . k 8 s . i o / v 1   k i n d :   S t o r a g e C l a s s   m e t a d a t a :   n a m e :   g l u s t e r - v o l - d e f a u l t   p r o v i s i o n e r :   k u b e r n e t e s . i o / g l u s t e r f s   p a r a m e t e r s :   r e s t u r l :   " h t t p : / / 1 9 2 . 1 6 8 . 1 0 . 1 0 0 : 8 0 8 0 "   r e s t u s e r :   " "   s e c r e t N a m e s p a c e :   " "   s e c r e t N a m e :   " "   a l l o w V o l u m e E x p a n s i o n :   t r u e   F o r   m o r e   i n f o r m a t i o n   a b o u t   p e r s i s t e n t   v o l u m e   c l a i m s ,   s e e   P e r s i s t e n t V o l u m e C l a i m s .


Question: What is PodNodeSelector?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   d e f a u l t s   a n d   l i m i t s   w h a t   n o d e   s e l e c t o r s   m a y   b e   u s e d   w i t h i n   a   n a m e s p a c e   b y   r e a d i n g   a   n a m e s p a c e   a n n o t a t i o n   a n d   a   g l o b a l   c o n f i g u r a t i o n .   T h i s   a d m i s s i o n   c o n t r o l l e r   i s   d i s a b l e d   b y   d e f a u l t .


Question: What is Configuration file format?

Answer: P o d N o d e S e l e c t o r   u s e s   a   c o n f i g u r a t i o n   f i l e   t o   s e t   o p t i o n s   f o r   t h e   b e h a v i o r   o f   t h e   b a c k e n d .   N o t e   t h a t   t h e   c o n f i g u r a t i o n   f i l e   f o r m a t   w i l l   m o v e   t o   a   v e r s i o n e d   f i l e   i n   a   f u t u r e   r e l e a s e .   T h i s   f i l e   m a y   b e   j s o n   o r   y a m l   a n d   h a s   t h e   f o l l o w i n g   f o r m a t :   p o d N o d e S e l e c t o r P l u g i n C o n f i g :   c l u s t e r D e f a u l t N o d e S e l e c t o r :   n a m e - o f - n o d e - s e l e c t o r   n a m e s p a c e 1 :   n a m e - o f - n o d e - s e l e c t o r   n a m e s p a c e 2 :   n a m e - o f - n o d e - s e l e c t o r   R e f e r e n c e   t h e   P o d N o d e S e l e c t o r   c o n f i g u r a t i o n   f i l e   f r o m   t h e   f i l e   p r o v i d e d   t o   t h e   A P I   s e r v e r ' s   c o m m a n d   l i n e   f l a g   - - a d m i s s i o n - c o n t r o l - c o n f i g - f i l e :   a p i V e r s i o n :   a p i s e r v e r . c o n f i g . k 8 s . i o / v 1   k i n d :   A d m i s s i o n C o n f i g u r a t i o n   p l u g i n s :   -   n a m e :   P o d N o d e S e l e c t o r   p a t h :   p o d n o d e s e l e c t o r . y a m l   . . .


Question: What is Configuration Annotation Format?

Answer: P o d N o d e S e l e c t o r   u s e s   t h e   a n n o t a t i o n   k e y   s c h e d u l e r . a l p h a . k u b e r n e t e s . i o / n o d e - s e l e c t o r   t o   a s s i g n   n o d e   s e l e c t o r s   t o   n a m e s p a c e s .   a p i V e r s i o n :   v 1   k i n d :   N a m e s p a c e   m e t a d a t a :   a n n o t a t i o n s :   s c h e d u l e r . a l p h a . k u b e r n e t e s . i o / n o d e - s e l e c t o r :   n a m e - o f - n o d e - s e l e c t o r   n a m e :   n a m e s p a c e 3


Question: What is Internal Behavior?

Answer: T h i s   a d m i s s i o n   c o n t r o l l e r   h a s   t h e   f o l l o w i n g   b e h a v i o r :   I f   t h e   N a m e s p a c e   h a s   a n   a n n o t a t i o n   w i t h   a   k e y   s c h e d u l e r . a l p h a . k u b e r n e t e s . i o / n o d e - s e l e c t o r ,   u s e   i t s   v a l u e   a s   t h e   n o d e   s e l e c t o r . I f   t h e   n a m e s p a c e   l a c k s   s u c h   a n   a n n o t a t i o n ,   u s e   t h e   c l u s t e r D e f a u l t N o d e S e l e c t o r   d e f i n e d   i n   t h e   P o d N o d e S e l e c t o r   p l u g i n   c o n f i g u r a t i o n   f i l e   a s   t h e   n o d e   s e l e c t o r . E v a l u a t e   t h e   p o d ' s   n o d e   s e l e c t o r   a g a i n s t   t h e   n a m e s p a c e   n o d e   s e l e c t o r   f o r   c o n f l i c t s .   C o n f l i c t s   r e s u l t   i n   r e j e c t i o n . E v a l u a t e   t h e   p o d ' s   n o d e   s e l e c t o r   a g a i n s t   t h e   n a m e s p a c e - s p e c i f i c   a l l o w e d   s e l e c t o r   d e f i n e d   t h e   p l u g i n   c o n f i g u r a t i o n   f i l e .   C o n f l i c t s   r e s u l t   i n   r e j e c t i o n .


Question: What is PodSecurity?

Answer: T y p e :   V a l i d a t i n g .   T h e   P o d S e c u r i t y   a d m i s s i o n   c o n t r o l l e r   c h e c k s   n e w   P o d s   b e f o r e   t h e y   a r e   a d m i t t e d ,   d e t e r m i n e s   i f   i t   s h o u l d   b e   a d m i t t e d   b a s e d   o n   t h e   r e q u e s t e d   s e c u r i t y   c o n t e x t   a n d   t h e   r e s t r i c t i o n s   o n   p e r m i t t e d   P o d   S e c u r i t y   S t a n d a r d s   f o r   t h e   n a m e s p a c e   t h a t   t h e   P o d   w o u l d   b e   i n .   S e e   t h e   P o d   S e c u r i t y   A d m i s s i o n   d o c u m e n t a t i o n   f o r   m o r e   i n f o r m a t i o n .   P o d S e c u r i t y   r e p l a c e d   a n   o l d e r   a d m i s s i o n   c o n t r o l l e r   n a m e d   P o d S e c u r i t y P o l i c y .


Question: What is PodTolerationRestriction?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   T h e   P o d T o l e r a t i o n R e s t r i c t i o n   a d m i s s i o n   c o n t r o l l e r   v e r i f i e s   a n y   c o n f l i c t   b e t w e e n   t o l e r a t i o n s   o f   a   p o d   a n d   t h e   t o l e r a t i o n s   o f   i t s   n a m e s p a c e .   I t   r e j e c t s   t h e   p o d   r e q u e s t   i f   t h e r e   i s   a   c o n f l i c t .   I t   t h e n   m e r g e s   t h e   t o l e r a t i o n s   a n n o t a t e d   o n   t h e   n a m e s p a c e   i n t o   t h e   t o l e r a t i o n s   o f   t h e   p o d .   T h e   r e s u l t i n g   t o l e r a t i o n s   a r e   c h e c k e d   a g a i n s t   a   l i s t   o f   a l l o w e d   t o l e r a t i o n s   a n n o t a t e d   t o   t h e   n a m e s p a c e .   I f   t h e   c h e c k   s u c c e e d s ,   t h e   p o d   r e q u e s t   i s   a d m i t t e d   o t h e r w i s e   i t   i s   r e j e c t e d .   I f   t h e   n a m e s p a c e   o f   t h e   p o d   d o e s   n o t   h a v e   a n y   a s s o c i a t e d   d e f a u l t   t o l e r a t i o n s   o r   a l l o w e d   t o l e r a t i o n s   a n n o t a t e d ,   t h e   c l u s t e r - l e v e l   d e f a u l t   t o l e r a t i o n s   o r   c l u s t e r - l e v e l   l i s t   o f   a l l o w e d   t o l e r a t i o n s   a r e   u s e d   i n s t e a d   i f   t h e y   a r e   s p e c i f i e d .   T o l e r a t i o n s   t o   a   n a m e s p a c e   a r e   a s s i g n e d   v i a   t h e   s c h e d u l e r . a l p h a . k u b e r n e t e s . i o / d e f a u l t T o l e r a t i o n s   a n n o t a t i o n   k e y .   T h e   l i s t   o f   a l l o w e d   t o l e r a t i o n s   c a n   b e   a d d e d   v i a   t h e   s c h e d u l e r . a l p h a . k u b e r n e t e s . i o / t o l e r a t i o n s W h i t e l i s t   a n n o t a t i o n   k e y .   E x a m p l e   f o r   n a m e s p a c e   a n n o t a t i o n s :   a p i V e


Question: What is PodTopologyLabels?

Answer: T y p e :   M u t a t i n g   T h e   P o d T o p o l o g y L a b e l s   a d m i s s i o n   c o n t r o l l e r   m u t a t e s   t h e   p o d s / b i n d i n g   s u b r e s o u r c e s   f o r   a l l   p o d s   b o u n d   t o   a   N o d e ,   a d d i n g   t o p o l o g y   l a b e l s   m a t c h i n g   t h o s e   o f   t h e   b o u n d   N o d e .   T h i s   a l l o w s   N o d e   t o p o l o g y   l a b e l s   t o   b e   a v a i l a b l e   a s   p o d   l a b e l s ,   w h i c h   c a n   b e   s u r f a c e d   t o   r u n n i n g   c o n t a i n e r s   u s i n g   t h e   D o w n w a r d   A P I .   T h e   l a b e l s   a v a i l a b l e   a s   a   r e s u l t   o f   t h i s   c o n t r o l l e r   a r e   t h e   t o p o l o g y . k u b e r n e t e s . i o / r e g i o n   a n d   t o p o l o g y . k u b e r e n t e s . i o / z o n e   l a b e l s .


Question: What is Note:?

Answer: T h i s   a d m i s s i o n   c o n t r o l l e r   i s   e n a b l e d   w h e n   t h e   P o d T o p o l o g y L a b e l s A d m i s s i o n   f e a t u r e   g a t e   i s   e n a b l e d .


Question: What is Priority?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   T h e   p r i o r i t y   a d m i s s i o n   c o n t r o l l e r   u s e s   t h e   p r i o r i t y C l a s s N a m e   f i e l d   a n d   p o p u l a t e s   t h e   i n t e g e r   v a l u e   o f   t h e   p r i o r i t y .   I f   t h e   p r i o r i t y   c l a s s   i s   n o t   f o u n d ,   t h e   P o d   i s   r e j e c t e d .


Question: What is ResourceQuota?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   w i l l   o b s e r v e   t h e   i n c o m i n g   r e q u e s t   a n d   e n s u r e   t h a t   i t   d o e s   n o t   v i o l a t e   a n y   o f   t h e   c o n s t r a i n t s   e n u m e r a t e d   i n   t h e   R e s o u r c e Q u o t a   o b j e c t   i n   a   N a m e s p a c e .   I f   y o u   a r e   u s i n g   R e s o u r c e Q u o t a   o b j e c t s   i n   y o u r   K u b e r n e t e s   d e p l o y m e n t ,   y o u   M U S T   u s e   t h i s   a d m i s s i o n   c o n t r o l l e r   t o   e n f o r c e   q u o t a   c o n s t r a i n t s .   S e e   t h e   R e s o u r c e Q u o t a   A P I   r e f e r e n c e   a n d   t h e   e x a m p l e   o f   R e s o u r c e   Q u o t a   f o r   m o r e   d e t a i l s .


Question: What is RuntimeClass?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   I f   y o u   d e f i n e   a   R u n t i m e C l a s s   w i t h   P o d   o v e r h e a d   c o n f i g u r e d ,   t h i s   a d m i s s i o n   c o n t r o l l e r   c h e c k s   i n c o m i n g   P o d s .   W h e n   e n a b l e d ,   t h i s   a d m i s s i o n   c o n t r o l l e r   r e j e c t s   a n y   P o d   c r e a t e   r e q u e s t s   t h a t   h a v e   t h e   o v e r h e a d   a l r e a d y   s e t .   F o r   P o d s   t h a t   h a v e   a   R u n t i m e C l a s s   c o n f i g u r e d   a n d   s e l e c t e d   i n   t h e i r   . s p e c ,   t h i s   a d m i s s i o n   c o n t r o l l e r   s e t s   . s p e c . o v e r h e a d   i n   t h e   P o d   b a s e d   o n   t h e   v a l u e   d e f i n e d   i n   t h e   c o r r e s p o n d i n g   R u n t i m e C l a s s .   S e e   a l s o   P o d   O v e r h e a d   f o r   m o r e   i n f o r m a t i o n .


Question: What is ServiceAccount?

Answer: T y p e :   M u t a t i n g   a n d   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   i m p l e m e n t s   a u t o m a t i o n   f o r   s e r v i c e A c c o u n t s .   T h e   K u b e r n e t e s   p r o j e c t   s t r o n g l y   r e c o m m e n d s   e n a b l i n g   t h i s   a d m i s s i o n   c o n t r o l l e r .   Y o u   s h o u l d   e n a b l e   t h i s   a d m i s s i o n   c o n t r o l l e r   i f   y o u   i n t e n d   t o   m a k e   a n y   u s e   o f   K u b e r n e t e s   S e r v i c e A c c o u n t   o b j e c t s .   T o   e n h a n c e   t h e   s e c u r i t y   m e a s u r e s   a r o u n d   S e c r e t s ,   u s e   s e p a r a t e   n a m e s p a c e s   t o   i s o l a t e   a c c e s s   t o   m o u n t e d   s e c r e t s .


Question: What is StorageObjectInUseProtection?

Answer: T y p e :   M u t a t i n g .   T h e   S t o r a g e O b j e c t I n U s e P r o t e c t i o n   p l u g i n   a d d s   t h e   k u b e r n e t e s . i o / p v c - p r o t e c t i o n   o r   k u b e r n e t e s . i o / p v - p r o t e c t i o n   f i n a l i z e r s   t o   n e w l y   c r e a t e d   P e r s i s t e n t   V o l u m e   C l a i m s   ( P V C s )   o r   P e r s i s t e n t   V o l u m e s   ( P V ) .   I n   c a s e   a   u s e r   d e l e t e s   a   P V C   o r   P V   t h e   P V C   o r   P V   i s   n o t   r e m o v e d   u n t i l   t h e   f i n a l i z e r   i s   r e m o v e d   f r o m   t h e   P V C   o r   P V   b y   P V C   o r   P V   P r o t e c t i o n   C o n t r o l l e r .   R e f e r   t o   t h e   S t o r a g e   O b j e c t   i n   U s e   P r o t e c t i o n   f o r   m o r e   d e t a i l e d   i n f o r m a t i o n .


Question: What is TaintNodesByCondition?

Answer: T y p e :   M u t a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   t a i n t s   n e w l y   c r e a t e d   N o d e s   a s   N o t R e a d y   a n d   N o S c h e d u l e .   T h a t   t a i n t i n g   a v o i d s   a   r a c e   c o n d i t i o n   t h a t   c o u l d   c a u s e   P o d s   t o   b e   s c h e d u l e d   o n   n e w   N o d e s   b e f o r e   t h e i r   t a i n t s   w e r e   u p d a t e d   t o   a c c u r a t e l y   r e f l e c t   t h e i r   r e p o r t e d   c o n d i t i o n s .


Question: What is ValidatingAdmissionPolicy?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   i m p l e m e n t s   t h e   C E L   v a l i d a t i o n   f o r   i n c o m i n g   m a t c h e d   r e q u e s t s .   I t   i s   e n a b l e d   w h e n   b o t h   f e a t u r e   g a t e   v a l i d a t i n g a d m i s s i o n p o l i c y   a n d   a d m i s s i o n r e g i s t r a t i o n . k 8 s . i o / v 1 a l p h a 1   g r o u p / v e r s i o n   a r e   e n a b l e d .   I f   a n y   o f   t h e   V a l i d a t i n g A d m i s s i o n P o l i c y   f a i l s ,   t h e   r e q u e s t   f a i l s .


Question: What is ValidatingAdmissionWebhook?

Answer: T y p e :   V a l i d a t i n g .   T h i s   a d m i s s i o n   c o n t r o l l e r   c a l l s   a n y   v a l i d a t i n g   w e b h o o k s   w h i c h   m a t c h   t h e   r e q u e s t .   M a t c h i n g   w e b h o o k s   a r e   c a l l e d   i n   p a r a l l e l ;   i f   a n y   o f   t h e m   r e j e c t s   t h e   r e q u e s t ,   t h e   r e q u e s t   f a i l s .   T h i s   a d m i s s i o n   c o n t r o l l e r   o n l y   r u n s   i n   t h e   v a l i d a t i o n   p h a s e ;   t h e   w e b h o o k s   i t   c a l l s   m a y   n o t   m u t a t e   t h e   o b j e c t ,   a s   o p p o s e d   t o   t h e   w e b h o o k s   c a l l e d   b y   t h e   M u t a t i n g A d m i s s i o n W e b h o o k   a d m i s s i o n   c o n t r o l l e r .   I f   a   w e b h o o k   c a l l e d   b y   t h i s   h a s   s i d e   e f f e c t s   ( f o r   e x a m p l e ,   d e c r e m e n t i n g   q u o t a )   i t   m u s t   h a v e   a   r e c o n c i l i a t i o n   s y s t e m ,   a s   i t   i s   n o t   g u a r a n t e e d   t h a t   s u b s e q u e n t   w e b h o o k s   o r   o t h e r   v a l i d a t i n g   a d m i s s i o n   c o n t r o l l e r s   w i l l   p e r m i t   t h e   r e q u e s t   t o   f i n i s h .   I f   y o u   d i s a b l e   t h e   V a l i d a t i n g A d m i s s i o n W e b h o o k ,   y o u   m u s t   a l s o   d i s a b l e   t h e   V a l i d a t i n g W e b h o o k C o n f i g u r a t i o n   o b j e c t   i n   t h e   a d m i s s i o n r e g i s t r a t i o n . k 8 s . i o / v 1   g r o u p / v e r s i o n   v i a   t h e   - - r u n t i m e - c o n f i g   f l a g .


Question: What is Is there a recommended set of admission controllers to use??

Answer: Y e s .   T h e   r e c o m m e n d e d   a d m i s s i o n   c o n t r o l l e r s   a r e   e n a b l e d   b y   d e f a u l t   ( s h o w n   h e r e ) ,   s o   y o u   d o   n o t   n e e d   t o   e x p l i c i t l y   s p e c i f y   t h e m .   Y o u   c a n   e n a b l e   a d d i t i o n a l   a d m i s s i o n   c o n t r o l l e r s   b e y o n d   t h e   d e f a u l t   s e t   u s i n g   t h e   - - e n a b l e - a d m i s s i o n - p l u g i n s   f l a g   ( o r d e r   d o e s n ' t   m a t t e r ) .


Question: What is Running Automated Tasks with a CronJob?

Answer: Running Automated Tasks with a CronJobThis page shows how to run automated tasks using Kubernetes CronJob object.Before you beginYou need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:iximiuz LabsKillercodaKodeKloudPlay with KubernetesCreating a CronJobCron jobs require a config file. Here is a manifest for a CronJob that runs a simple demonstration task every minute:application/job/cronjob.yaml apiVersion: batch/v1 kind: CronJob metadata: name: hello spec: schedule: "* * * * *" jobTemplate: spec: template: spec: containers: - name: hello image: busybox:1.28 imagePullPolicy: IfNotPresent command: - /bin/sh - -c - date; echo Hello from the Kubernetes cluster restartPolicy: OnFailure Run the example CronJob by using this command:kubectl create -f https://k8s.io/examples/application/job/cronjob.yaml The output is similar to this:cronjob.batch/hello created After creating the cron job, get its status using this command:kubectl get cronjob hello The output is similar to this:NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE hello */1 * * * * False 0 <none> 10s As you can see from the results of the command, the cron job has not scheduled or run any jobs yet. Watch for the job to be created in around one minute:kubectl get jobs --watch The output is similar to this:NAME COMPLETIONS DURATION AGE hello-4111706356 0/1 0s hello-4111706356 0/1 0s 0s hello-4111706356 1/1 5s 5s Now you've seen one running job scheduled by the "hello" cron job. You can stop watching the job and view the cron job again to see that it scheduled the job:kubectl get cronjob hello The output is similar to this:NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE hello */1 * * * * False 0 50s 75s You should see that the cron job hello successfully scheduled a job at the time specified in LAST SCHEDULE. There are currently 0 active jobs, meaning that the job has completed or failed.Now, find the pods that the last scheduled job created and view the standard output of one of the pods.Note:The job name is different from the pod name.# Replace "hello-4111706356" with the job name in your system pods=$(kubectl get pods --selector=job-name=hello-4111706356 --output=jsonpath={.items[*].metadata.name}) Show the pod log:kubectl logs $pods The output is similar to this:Fri Feb 22 11:02:09 UTC 2019 Hello from the Kubernetes cluster Deleting a CronJobWhen you don't need a cron job any more, delete it with kubectl delete cronjob <cronjob name>:kubectl delete cronjob hello Deleting the cron job removes all the jobs and pods it created and stops it from creating additional jobs. You can read more about removing jobs in garbage collection.


Question: How does Running Automated Tasks with a CronJob work?

Answer: Running Automated Tasks with a CronJobThis page shows how to run automated tasks using Kubernetes CronJob object.Before you beginYou need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:iximiuz LabsKillercodaKodeKloudPlay with KubernetesCreating a CronJobCron jobs require a config file. Here is a manifest for a CronJob that runs a simple demonstration task every minute:application/job/cronjob.yaml apiVersion: batch/v1 kind: CronJob metadata: name: hello spec: schedule: "* * * * *" jobTemplate: spec: template: spec: containers: - name: hello image: busybox:1.28 imagePullPolicy: IfNotPresent command: - /bin/sh - -c - date; echo Hello from the Kubernetes cluster restartPolicy: OnFailure Run the example CronJob by using this command:kubectl create -f https://k8s.io/examples/application/job/cronjob.yaml The output is similar to this:cronjob.batch/hello created After creating the cron job, get its status using this command:kubectl get cronjob hello The output is similar to this:NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE hello */1 * * * * False 0 <none> 10s As you can see from the results of the command, the cron job has not scheduled or run any jobs yet. Watch for the job to be created in around one minute:kubectl get jobs --watch The output is similar to this:NAME COMPLETIONS DURATION AGE hello-4111706356 0/1 0s hello-4111706356 0/1 0s 0s hello-4111706356 1/1 5s 5s Now you've seen one running job scheduled by the "hello" cron job. You can stop watching the job and view the cron job again to see that it scheduled the job:kubectl get cronjob hello The output is similar to this:NAME SCHEDULE SUSPEND ACTIVE LAST SCHEDULE AGE hello */1 * * * * False 0 50s 75s You should see that the cron job hello successfully scheduled a job at the time specified in LAST SCHEDULE. There are currently 0 active jobs, meaning that the job has completed or failed.Now, find the pods that the last scheduled job created and view the standard output of one of the pods.Note:The job name is different from the pod name.# Replace "hello-4111706356" with the job name in your system pods=$(kubectl get pods --selector=job-name=hello-4111706356 --output=jsonpath={.items[*].metadata.name}) Show the pod log:kubectl logs $pods The output is similar to this:Fri Feb 22 11:02:09 UTC 2019 Hello from the Kubernetes cluster Deleting a CronJobWhen you don't need a cron job any more, delete it with kubectl delete cronjob <cronjob name>:kubectl delete cronjob hello Deleting the cron job removes all the jobs and pods it created and stops it from creating additional jobs. You can read more about removing jobs in garbage collection.