OSDOCS-9647: adds network policy intro MicroShift

_topic_maps/_topic_map_ms.yml

@@ -402,10 +402,16 @@ Topics:
   File: microshift-cni
 - Name: Using networking settings
   File: microshift-networking-settings
+- Name: Network policies
+  Dir: microshift-network-policy
+  Topics:
+  - Name: Setting network policies
+    File: microshift-network-policy-index
 - Name: Firewall configuration
   File: microshift-firewall
 - Name: Networking settings for fully disconnected hosts
   File: microshift-disconnected-network-config
+
 ---
 Name: Storage
 Dir: microshift_storage

microshift_networking/microshift-network-policy/_attributes

@@ -0,0 +1 @@
+../_attributes

microshift_networking/microshift-network-policy/images

@@ -0,0 +1 @@
+../images

microshift_networking/microshift-network-policy/microshift-network-policy-index.adoc

@@ -0,0 +1,13 @@
+:_mod-docs-content-type: ASSEMBLY
+[id="microshift-network-policies"]
+= Setting network policies
+include::_attributes/attributes-microshift.adoc[]
+:context: microshift-network-policies
+toc::[]
+
+Learn how to apply network policies to restrict or allow network traffic to pods in your cluster.
+
+include::modules/microshift-nw-network-policy-intro.adoc[leveloffset=+1]
+
+//OCP module, edit with conditionals
+include::modules/nw-networkpolicy-optimize-ovn.adoc[leveloffset=+1]

microshift_networking/microshift-network-policy/modules

@@ -0,0 +1 @@
+../modules

microshift_networking/microshift-network-policy/snippets

@@ -0,0 +1 @@
+../snippets/

modules/microshift-nw-network-policy-intro.adoc

@@ -0,0 +1,136 @@
+// Module included in the following assemblies:
+//
+// * microshift_networking/microshift-network-policies.adoc
+
+:_mod-docs-content-type: CONCEPT
+[id="microshift-nw-network-policy-intro_{context}"]
+= How network policy works in {microshift-short}
+
+In a cluster using the default OVN-Kubernetes Container Network Interface (CNI) plugin for {microshift-short}, network isolation is controlled by both firewalld, which is configured on the host, and by `NetworkPolicy` objects created within {microshift-short}. Simultaneous use of firewalld and `NetworkPolicy` is supported.
+
+* Network policies work only within boundaries of OVN-Kubernetes-controlled traffic, so they can apply to every situation except for `hostPort/hostNetwork` enabled pods.
+
+* Firewalld settings also do not apply to `hostPort/hostNetwork` enabled pods.
+
+[NOTE]
+====
+Firewalld rules run before any `NetworkPolicy` is enforced.
+====
+
+[WARNING]
+====
+Network policy does not apply to the host network namespace. Pods with host networking enabled are unaffected by network policy rules. However, pods connecting to the host-networked pods might be affected by the network policy rules.
+
+Network policies cannot block traffic from localhost.
+====
+
+By default, all pods in a {microshift-short} node are accessible from other pods and network endpoints. To isolate one or more pods in a cluster, you can create `NetworkPolicy` objects to indicate allowed incoming connections. You can create and delete `NetworkPolicy` objects.
+
+If a pod is matched by selectors in one or more `NetworkPolicy` objects, then the pod accepts only connections that are allowed by at least one of those `NetworkPolicy` objects. A pod that is not selected by any `NetworkPolicy` objects is fully accessible.
+
+A network policy applies to only the TCP, UDP, ICMP, and SCTP protocols. Other protocols are not affected.
+
+The following example `NetworkPolicy` objects demonstrate supporting different scenarios:
+
+* Deny all traffic:
++
+To make a project deny by default, add a `NetworkPolicy` object that matches all pods but accepts no traffic:
++
+[source,yaml]
+----
+kind: NetworkPolicy
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: deny-by-default
+spec:
+  podSelector: {}
+  ingress: []
+----
+
+* Allow connections from the default router, which is the ingress in {microshift-short}:
++
+To allow connections from the {microshift-short} default router, add the following `NetworkPolicy` object:
++
+[source,yaml]
+----
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: allow-from-openshift-ingress
+spec:
+  ingress:
+  - from:
+    - namespaceSelector:
+        matchLabels:
+          ingresscontroller.operator.openshift.io/deployment-ingresscontroller: default
+  podSelector: {}
+  policyTypes:
+  - Ingress
+----
+
+* Only accept connections from pods within the same namespace:
++
+To make pods accept connections from other pods in the same namespace, but reject all other connections from pods in other namespaces, add the following `NetworkPolicy` object:
++
+[source,yaml]
+----
+kind: NetworkPolicy
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: allow-same-namespace
+spec:
+  podSelector: {}
+  ingress:
+  - from:
+    - podSelector: {}
+----
+
+* Only allow HTTP and HTTPS traffic based on pod labels:
++
+To enable only HTTP and HTTPS access to the pods with a specific label (`role=frontend` in following example), add a `NetworkPolicy` object similar to the following:
++
+[source,yaml]
+----
+kind: NetworkPolicy
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: allow-http-and-https
+spec:
+  podSelector:
+    matchLabels:
+      role: frontend
+  ingress:
+  - ports:
+    - protocol: TCP
+      port: 80
+    - protocol: TCP
+      port: 443
+----
+
+* Accept connections by using both namespace and pod selectors:
++
+To match network traffic by combining namespace and pod selectors, you can use a `NetworkPolicy` object similar to the following:
++
+[source,yaml]
+----
+kind: NetworkPolicy
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: allow-pod-and-namespace-both
+spec:
+  podSelector:
+    matchLabels:
+      name: test-pods
+  ingress:
+    - from:
+      - namespaceSelector:
+          matchLabels:
+            project: project_name
+        podSelector:
+          matchLabels:
+            name: test-pods
+----
+
+`NetworkPolicy` objects are additive, which means you can combine multiple `NetworkPolicy` objects together to satisfy complex network requirements.
+
+For example, for the `NetworkPolicy` objects defined in previous examples, you can define both `allow-same-namespace` and `allow-http-and-https` policies. That configuration allows the pods with the label `role=frontend` to accept any connection allowed by each policy. That is, connections on any port from pods in the same namespace, and connections on ports `80` and `443` from pods in any namespace.