Add Configure Namespace Isolation task

_data/tasks.yml

@@ -103,6 +103,7 @@ toc:
   - docs/tasks/administer-cluster/upgrade-1-6.md
   - docs/tasks/administer-cluster/namespaces.md
   - docs/tasks/administer-cluster/namespaces-walkthrough.md
+  - docs/tasks/administer-cluster/configure-namespace-isolation.md
   - docs/tasks/administer-cluster/dns-horizontal-autoscaling.md
   - docs/tasks/administer-cluster/safely-drain-node.md
   - docs/tasks/administer-cluster/declare-network-policy.md

docs/tasks/administer-cluster/configure-namespace-isolation.md

@@ -0,0 +1,90 @@
+---
+assignees:
+- thockin
+- caseydavenport
+- danwinship
+title: Configuring Namespace Isolation
+---
+
+* TOC
+{:toc}
+
+## Prerequisites
+
+Network policies are implemented by the network plugin, so you must be using a networking solution which supports `NetworkPolicy` - simply creating the resource without a controller to implement it will have no effect.
+
+## Configuring Namespace Isolation
+
+By default, all traffic is allowed between all pods (and `NetworkPolicy` resources have no effect).
+
+Isolation can be configured on a per-namespace basis. Currently, only isolation on inbound traffic (ingress) can be defined. When a namespace has been configured to isolate inbound traffic, all traffic to pods in that namespace (even from other pods in the same namespace) will be blocked. `NetworkPolicy` objects can then be added to the isolated namespace to specify what traffic should be allowed.
+
+Isolation is enabled via the `NetworkPolicy` field of the `Namespace` object. To enable isolation via `kubectl`:
+
+```shell
+{% raw %}
+kubectl patch ns <namespace> -p '{"spec": {"networkPolicy": {"ingress": {"isolation": "DefaultDeny"}}}}'
+{% endraw %}
+```
+
+To disable it:
+
+```shell
+{% raw %}
+kubectl patch ns <namespace> -p '{"spec": {"networkPolicy": null}}'
+{% endraw %}
+```
+
+NOTE: older network plugins may instead require the v1beta1 syntax, using an annotation:
+
+```shell
+{% raw %}
+kubectl annotate ns <namespace> "net.beta.kubernetes.io/network-policy={\"ingress\": {\"isolation\": \"DefaultDeny\"}}"
+{% endraw %}
+```
+
+## The `NetworkPolicy` Resource
+
+See the [api-reference](/docs/api-reference/networking/v1/definitions/#_v1_networkpolicy) for a full definition of the resource.
+
+An example `NetworkPolicy` might look like this:
+
+```yaml
+apiVersion: networking/v1
+kind: NetworkPolicy
+metadata:
+  name: test-network-policy
+  namespace: default
+spec:
+  podSelector:
+    matchLabels:
+      role: db
+  ingress:
+  - from:
+    - namespaceSelector:
+        matchLabels:
+          project: myproject
+    - podSelector:
+        matchLabels:
+          role: frontend
+    ports:
+    - protocol: tcp
+      port: 6379
+```
+
+*POSTing this to the API server will have no effect unless your chosen networking solution supports network policy.*
+
+__Mandatory Fields__: As with all other Kubernetes config, a `NetworkPolicy` needs `apiVersion`, `kind`, and `metadata` fields.  For general information about working with config files, see [here](/docs/user-guide/simple-yaml), [here](/docs/user-guide/configuring-containers), and [here](/docs/user-guide/working-with-resources).
+
+__spec__: `NetworkPolicy` [spec](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/docs/devel/api-conventions.md#spec-and-status) has all the information needed to define a particular network policy in the given namespace.
+
+__podSelector__: Each `NetworkPolicy` includes a `podSelector` which selects the grouping of pods to which the `ingress` rules in the policy apply. The example policy selects pods with the label "role=db".
+
+__ingress__: Each `NetworkPolicy` includes a list of whitelist `ingress` rules.  Each rule allows traffic which matches both the `from` and `ports` sections. The example policy contains a single rule, which matches traffic on a single port, from either of two sources, the first specified via a `namespaceSelector` and the second specified via a `podSelector`.
+
+So, the example NetworkPolicy:
+
+1. allows connections to tcp port 6379 of "role=db" pods in the "default" namespace from any pod in the "default" namespace with the label "role=frontend"
+2. allows connections to tcp port 6379 of "role=db" pods in the "default" namespace from any pod in a namespace with the label "project=myproject"
+
+See the [NetworkPolicy getting started guide](/docs/getting-started-guides/network-policy/walkthrough) for further examples.