Cleanup and implement style guidelines. (#18980)
* Reworded paragraphs to reduce ambiguity. * Added min-kubernetes-server-version metadata. * Converted yaml to a downloadable resource.
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@@ -3,6 +3,7 @@ reviewers:
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- caseydavenport
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- danwinship
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title: Declare Network Policy
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min-kubernetes-server-version: v1.8
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content_template: templates/task
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---
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{{% capture overview %}}
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@@ -30,7 +31,7 @@ The above list is sorted alphabetically by product name, not by recommendation o
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## Create an `nginx` deployment and expose it via a service
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To see how Kubernetes network policy works, start off by creating an `nginx` deployment.
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To see how Kubernetes network policy works, start off by creating an `nginx` Deployment.
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```console
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kubectl create deployment nginx --image=nginx
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@@ -39,7 +40,7 @@ kubectl create deployment nginx --image=nginx
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deployment.apps/nginx created
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```
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And expose it via a service.
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Expose the Deployment through a Service called `nginx`.
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```console
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kubectl expose deployment nginx --port=80
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@@ -49,7 +50,7 @@ kubectl expose deployment nginx --port=80
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service/nginx exposed
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```
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This runs a `nginx` pods in the default namespace, and exposes it through a service called `nginx`.
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The above commands create a Deployment with an nginx Pod and expose the Deployment through a Service named `nginx`. The `nginx` Pod and Deployment are found in the `default` namespace.
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```console
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kubectl get svc,pod
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@@ -64,59 +65,43 @@ NAME READY STATUS RESTARTS AGE
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pod/nginx-701339712-e0qfq 1/1 Running 0 35s
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```
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## Test the service by accessing it from another pod
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## Test the service by accessing it from another Pod
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You should be able to access the new `nginx` service from other pods. To test, access the service from another pod in the default namespace. Make sure you haven't enabled isolation on the namespace.
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Start a busybox container, and use `wget` on the `nginx` service:
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You should be able to access the new `nginx` service from other Pods. To access the `nginx` Service from another Pod in the `default` namespace, start a busybox container:
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```console
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kubectl run --generator=run-pod/v1 busybox --rm -ti --image=busybox -- /bin/sh
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```
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```console
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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In your shell, run the following command:
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Hit enter for command prompt
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```shell
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wget --spider --timeout=1 nginx
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```
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/ # wget --spider --timeout=1 nginx
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```none
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Connecting to nginx (10.100.0.16:80)
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/ #
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remote file exists
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```
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## Limit access to the `nginx` service
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Let's say you want to limit access to the `nginx` service so that only pods with the label `access: true` can query it. To do that, create a `NetworkPolicy` that allows connections only from those pods:
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To limit the access to the `nginx` service so that only Pods with the label `access: true` can query it, create a NetworkPolicy object as follows:
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```yaml
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apiVersion: networking.k8s.io/v1
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kind: NetworkPolicy
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metadata:
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name: access-nginx
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spec:
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podSelector:
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matchLabels:
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app: nginx
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ingress:
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- from:
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- podSelector:
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matchLabels:
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access: "true"
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```
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{{< codenew file="service/networking/nginx-policy.yaml" >}}
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{{< note >}}
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In the case, the label `app=nginx` is automatically added.
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NetworkPolicy includes a `podSelector` which selects the grouping of Pods to which the policy applies. You can see this policy selects Pods with the label `app=nginx`. The label was automatically added to the Pod in the `nginx` Deployment. An empty `podSelector` selects all pods in the namespace.
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{{< /note >}}
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## Assign the policy to the service
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Use kubectl to create a NetworkPolicy from the above nginx-policy.yaml file:
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Use kubectl to create a NetworkPolicy from the above `nginx-policy.yaml` file:
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```console
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kubectl apply -f nginx-policy.yaml
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kubectl apply -f https://k8s.io/examples/service/networking/nginx-policy.yaml
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```
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```none
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@@ -124,40 +109,40 @@ networkpolicy.networking.k8s.io/access-nginx created
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```
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## Test access to the service when access label is not defined
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If we attempt to access the nginx Service from a pod without the correct labels, the request will now time out:
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When you attempt to access the `nginx` Service from a Pod without the correct labels, the request times out:
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```console
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kubectl run --generator=run-pod/v1 busybox --rm -ti --image=busybox -- /bin/sh
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```
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```console
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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In your shell, run the command:
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Hit enter for command prompt
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```shell
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wget --spider --timeout=1 nginx
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```
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/ # wget --spider --timeout=1 nginx
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```none
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Connecting to nginx (10.100.0.16:80)
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wget: download timed out
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/ #
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```
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## Define access label and test again
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Create a pod with the correct labels, and you'll see that the request is allowed:
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You can create a Pod with the correct labels to see that the request is allowed:
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```console
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kubectl run --generator=run-pod/v1 busybox --rm -ti --labels="access=true" --image=busybox -- /bin/sh
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```
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```console
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Waiting for pod default/busybox-472357175-y0m47 to be running, status is Pending, pod ready: false
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In your shell, run the command:
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Hit enter for command prompt
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/ # wget --spider --timeout=1 nginx
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Connecting to nginx (10.100.0.16:80)
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/ #
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```shell
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wget --spider --timeout=1 nginx
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```
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```none
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Connecting to nginx (10.100.0.16:80)
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remote file exists
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```
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{{% /capture %}}
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@@ -0,0 +1,13 @@
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apiVersion: networking.k8s.io/v1
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kind: NetworkPolicy
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metadata:
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name: access-nginx
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spec:
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podSelector:
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matchLabels:
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app: nginx
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ingress:
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- from:
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- podSelector:
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matchLabels:
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access: "true"
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