Postinstallation network configuration | Post-installation configuration

Using the Cluster Network Operator
Network configuration tasks
- Creating default network policies for a new project

After installing OpenShift Container Platform, you can further expand and customize your network to your requirements.

Using the Cluster Network Operator

You can use the Cluster Network Operator (CNO) to deploy and manage cluster network components on an OpenShift Container Platform cluster, including the Container Network Interface (CNI) network plugin selected for the cluster during installation. For more information, see Cluster Network Operator in OpenShift Container Platform.

Network configuration tasks

Creating default network policies for a new project

As a cluster administrator, you can modify the new project template to automatically include NetworkPolicy objects when you create a new project.

Modifying the template for new projects

As a cluster administrator, you can modify the default project template so that new projects are created using your custom requirements.

To create your own custom project template:

Procedure

Generate the default project template:

$ oc adm create-bootstrap-project-template -o yaml > template.yaml

Use a text editor to modify the generated template.yaml file by adding objects or modifying existing objects.
The project template must be created in the openshift-config namespace. Load your modified template:
```
$ oc create -f template.yaml -n openshift-config
```
Edit the project configuration resource using the web console or CLI.
- Using the web console:
  1. Navigate to the Administration → Cluster Settings page.
  2. Click Configuration to view all configuration resources.
  3. Find the entry for Project and click Edit YAML.
- Using the CLI:
  1. Edit the project.config.openshift.io/cluster resource:
    
    $ oc edit project.config.openshift.io/cluster
Update the spec section to include the projectRequestTemplate and name parameters, and set the name of your uploaded project template. The default name is project-request.
Project configuration resource with custom project template
```
apiVersion: config.openshift.io/v1
kind: Project
metadata:
# ...
spec:
  projectRequestTemplate:
    name: <template_name>
# ...
```
After you save your changes, create a new project to verify that your changes were successfully applied.

Adding network policies to the new project template

As a cluster administrator, you can add network policies to the default template for new projects. OpenShift Container Platform will automatically create all the NetworkPolicy objects specified in the template in the project.

Prerequisites

Your cluster uses a default CNI network plugin that supports NetworkPolicy objects, such as the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN.
You installed the OpenShift CLI (oc).
You must log in to the cluster with a user with cluster-admin privileges.
You must have created a custom default project template for new projects.

Procedure

Edit the default template for a new project by running the following command:
```
$ oc edit template <project_template> -n openshift-config
```
Replace <project_template> with the name of the default template that you configured for your cluster. The default template name is project-request.

In the template, add each NetworkPolicy object as an element to the objects parameter. The objects parameter accepts a collection of one or more objects.

In the following example, the objects parameter collection includes several NetworkPolicy objects.

objects:
- apiVersion: networking.k8s.io/v1
  kind: NetworkPolicy
  metadata:
    name: allow-from-same-namespace
  spec:
    podSelector: {}
    ingress:
    - from:
      - podSelector: {}
- apiVersion: networking.k8s.io/v1
  kind: NetworkPolicy
  metadata:
    name: allow-from-openshift-ingress
  spec:
    ingress:
    - from:
      - namespaceSelector:
          matchLabels:
            network.openshift.io/policy-group: ingress
    podSelector: {}
    policyTypes:
    - Ingress
- apiVersion: networking.k8s.io/v1
  kind: NetworkPolicy
  metadata:
    name: allow-from-kube-apiserver-operator
  spec:
    ingress:
    - from:
      - namespaceSelector:
          matchLabels:
            kubernetes.io/metadata.name: openshift-kube-apiserver-operator
        podSelector:
          matchLabels:
            app: kube-apiserver-operator
    policyTypes:
    - Ingress
...

Optional: Create a new project to confirm that your network policy objects are created successfully by running the following commands:
1. Create a new project:
  $ oc new-project <project> (1)
  1 Replace <project> with the name for the project you are creating.
2. Confirm that the network policy objects in the new project template exist in the new project:
  $ oc get networkpolicy NAME POD-SELECTOR AGE allow-from-openshift-ingress <none> 7s allow-from-same-namespace <none> 7s