Chapter 21. Network policy 21.1. About network policy As a developer, you can define network policies that restrict traffic to pods in your cluster. 21.1.1. About network policy In a cluster using a network plugin that supports Kubernetes network policy, network isolation is controlled entirely by NetworkPolicy objects. In OpenShift Container Platform 4.15, OpenShift SDN supports using network policy in its default network isolation mode. 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 or from their resident nodes. By default, all pods in a project are accessible from other pods and network endpoints. To isolate one or more pods in a project, you can create NetworkPolicy objects in that project to indicate the allowed incoming connections. Project administrators can create and delete NetworkPolicy objects within their own project. If a pod is matched by selectors in one or more NetworkPolicy objects, then the pod will accept 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: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default spec: podSelector: {} ingress: [] Only allow connections from the OpenShift Container Platform Ingress Controller: To make a project allow only connections from the OpenShift Container Platform Ingress Controller, add the following NetworkPolicy object. 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 Only accept connections from pods within a project: Important To allow ingress connections from hostNetwork pods in the same namespace, you need to apply the allow-from-hostnetwork policy together with the allow-same-namespace policy. To make pods accept connections from other pods in the same project, but reject all other connections from pods in other projects, add the following NetworkPolicy object: 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: 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: 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 samples, you can define both allow-same-namespace and allow-http-and-https policies within the same project. Thus allowing 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. 21.1.1.1. Using the allow-from-router network policy Use the following NetworkPolicy to allow external traffic regardless of the router configuration: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-router spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/ingress: "" 1 podSelector: {} policyTypes: - Ingress 1 policy-group.network.openshift.io/ingress:"" label supports both OpenShift-SDN and OVN-Kubernetes. 21.1.1.2. Using the allow-from-hostnetwork network policy Add the following allow-from-hostnetwork NetworkPolicy object to direct traffic from the host network pods. apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-hostnetwork spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/host-network: "" podSelector: {} policyTypes: - Ingress 21.1.2. Optimizations for network policy with OpenShift SDN Use a network policy to isolate pods that are differentiated from one another by labels within a namespace. It is inefficient to apply NetworkPolicy objects to large numbers of individual pods in a single namespace. Pod labels do not exist at the IP address level, so a network policy generates a separate Open vSwitch (OVS) flow rule for every possible link between every pod selected with a podSelector . For example, if the spec podSelector and the ingress podSelector within a NetworkPolicy object each match 200 pods, then 40,000 (200*200) OVS flow rules are generated. This might slow down a node. When designing your network policy, refer to the following guidelines: Reduce the number of OVS flow rules by using namespaces to contain groups of pods that need to be isolated. NetworkPolicy objects that select a whole namespace, by using the namespaceSelector or an empty podSelector , generate only a single OVS flow rule that matches the VXLAN virtual network ID (VNID) of the namespace. Keep the pods that do not need to be isolated in their original namespace, and move the pods that require isolation into one or more different namespaces. Create additional targeted cross-namespace network policies to allow the specific traffic that you do want to allow from the isolated pods. 21.1.3. Optimizations for network policy with OVN-Kubernetes network plugin When designing your network policy, refer to the following guidelines: For network policies with the same spec.podSelector spec, it is more efficient to use one network policy with multiple ingress or egress rules, than multiple network policies with subsets of ingress or egress rules. Every ingress or egress rule based on the podSelector or namespaceSelector spec generates the number of OVS flows proportional to number of pods selected by network policy + number of pods selected by ingress or egress rule . Therefore, it is preferable to use the podSelector or namespaceSelector spec that can select as many pods as you need in one rule, instead of creating individual rules for every pod. For example, the following policy contains two rules: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: test-network-policy spec: podSelector: {} ingress: - from: - podSelector: matchLabels: role: frontend - from: - podSelector: matchLabels: role: backend The following policy expresses those same two rules as one: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: test-network-policy spec: podSelector: {} ingress: - from: - podSelector: matchExpressions: - {key: role, operator: In, values: [frontend, backend]} The same guideline applies to the spec.podSelector spec. If you have the same ingress or egress rules for different network policies, it might be more efficient to create one network policy with a common spec.podSelector spec. For example, the following two policies have different rules: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy1 spec: podSelector: matchLabels: role: db ingress: - from: - podSelector: matchLabels: role: frontend --- apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy2 spec: podSelector: matchLabels: role: client ingress: - from: - podSelector: matchLabels: role: frontend The following network policy expresses those same two rules as one: apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy3 spec: podSelector: matchExpressions: - {key: role, operator: In, values: [db, client]} ingress: - from: - podSelector: matchLabels: role: frontend You can apply this optimization when only multiple selectors are expressed as one. In cases where selectors are based on different labels, it may not be possible to apply this optimization. In those cases, consider applying some new labels for network policy optimization specifically. 21.1.4. steps Creating a network policy Optional: Defining a default network policy 21.1.5. Additional resources Projects and namespaces Configuring multitenant network policy NetworkPolicy API 21.2. Creating a network policy As a user with the admin role, you can create a network policy for a namespace. 21.2.1. Example NetworkPolicy object The following annotates an example NetworkPolicy object: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017 1 The name of the NetworkPolicy object. 2 A selector that describes the pods to which the policy applies. The policy object can only select pods in the project that defines the NetworkPolicy object. 3 A selector that matches the pods from which the policy object allows ingress traffic. The selector matches pods in the same namespace as the NetworkPolicy. 4 A list of one or more destination ports on which to accept traffic. 21.2.2. Creating a network policy using the CLI To define granular rules describing ingress or egress network traffic allowed for namespaces in your cluster, you can create a network policy. Note If you log in with a user with the cluster-admin role, then you can create a network policy in any namespace in the cluster. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace that the network policy applies to. Procedure Create a policy rule: Create a <policy_name>.yaml file: USD touch <policy_name>.yaml where: <policy_name> Specifies the network policy file name. Define a network policy in the file that you just created, such as in the following examples: Deny ingress from all pods in all namespaces This is a fundamental policy, blocking all cross-pod networking other than cross-pod traffic allowed by the configuration of other Network Policies. kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default spec: podSelector: {} policyTypes: - Ingress ingress: [] Allow ingress from all pods in the same namespace kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-same-namespace spec: podSelector: ingress: - from: - podSelector: {} Allow ingress traffic to one pod from a particular namespace This policy allows traffic to pods labelled pod-a from pods running in namespace-y . kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-traffic-pod spec: podSelector: matchLabels: pod: pod-a policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: namespace-y To create the network policy object, enter the following command: USD oc apply -f <policy_name>.yaml -n <namespace> where: <policy_name> Specifies the network policy file name. <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. Example output networkpolicy.networking.k8s.io/deny-by-default created Note If you log in to the web console with cluster-admin privileges, you have a choice of creating a network policy in any namespace in the cluster directly in YAML or from a form in the web console. 21.2.3. Creating a default deny all network policy This is a fundamental policy, blocking all cross-pod networking other than network traffic allowed by the configuration of other deployed network policies. This procedure enforces a default deny-by-default policy. Note If you log in with a user with the cluster-admin role, then you can create a network policy in any namespace in the cluster. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace that the network policy applies to. Procedure Create the following YAML that defines a deny-by-default policy to deny ingress from all pods in all namespaces. Save the YAML in the deny-by-default.yaml file: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default namespace: default 1 spec: podSelector: {} 2 ingress: [] 3 1 namespace: default deploys this policy to the default namespace. 2 podSelector: is empty, this means it matches all the pods. Therefore, the policy applies to all pods in the default namespace. 3 There are no ingress rules specified. This causes incoming traffic to be dropped to all pods. Apply the policy by entering the following command: USD oc apply -f deny-by-default.yaml Example output networkpolicy.networking.k8s.io/deny-by-default created 21.2.4. Creating a network policy to allow traffic from external clients With the deny-by-default policy in place you can proceed to configure a policy that allows traffic from external clients to a pod with the label app=web . Note If you log in with a user with the cluster-admin role, then you can create a network policy in any namespace in the cluster. Follow this procedure to configure a policy that allows external service from the public Internet directly or by using a Load Balancer to access the pod. Traffic is only allowed to a pod with the label app=web . Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace that the network policy applies to. Procedure Create a policy that allows traffic from the public Internet directly or by using a load balancer to access the pod. Save the YAML in the web-allow-external.yaml file: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-external namespace: default spec: policyTypes: - Ingress podSelector: matchLabels: app: web ingress: - {} Apply the policy by entering the following command: USD oc apply -f web-allow-external.yaml Example output networkpolicy.networking.k8s.io/web-allow-external created This policy allows traffic from all resources, including external traffic as illustrated in the following diagram: 21.2.5. Creating a network policy allowing traffic to an application from all namespaces Note If you log in with a user with the cluster-admin role, then you can create a network policy in any namespace in the cluster. Follow this procedure to configure a policy that allows traffic from all pods in all namespaces to a particular application. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace that the network policy applies to. Procedure Create a policy that allows traffic from all pods in all namespaces to a particular application. Save the YAML in the web-allow-all-namespaces.yaml file: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-all-namespaces namespace: default spec: podSelector: matchLabels: app: web 1 policyTypes: - Ingress ingress: - from: - namespaceSelector: {} 2 1 Applies the policy only to app:web pods in default namespace. 2 Selects all pods in all namespaces. Note By default, if you omit specifying a namespaceSelector it does not select any namespaces, which means the policy allows traffic only from the namespace the network policy is deployed to. Apply the policy by entering the following command: USD oc apply -f web-allow-all-namespaces.yaml Example output networkpolicy.networking.k8s.io/web-allow-all-namespaces created Verification Start a web service in the default namespace by entering the following command: USD oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80 Run the following command to deploy an alpine image in the secondary namespace and to start a shell: USD oc run test-USDRANDOM --namespace=secondary --rm -i -t --image=alpine -- sh Run the following command in the shell and observe that the request is allowed: # wget -qO- --timeout=2 http://web.default Expected output <!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> html { color-scheme: light dark; } body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html> 21.2.6. Creating a network policy allowing traffic to an application from a namespace Note If you log in with a user with the cluster-admin role, then you can create a network policy in any namespace in the cluster. Follow this procedure to configure a policy that allows traffic to a pod with the label app=web from a particular namespace. You might want to do this to: Restrict traffic to a production database only to namespaces where production workloads are deployed. Enable monitoring tools deployed to a particular namespace to scrape metrics from the current namespace. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace that the network policy applies to. Procedure Create a policy that allows traffic from all pods in a particular namespaces with a label purpose=production . Save the YAML in the web-allow-prod.yaml file: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-prod namespace: default spec: podSelector: matchLabels: app: web 1 policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: purpose: production 2 1 Applies the policy only to app:web pods in the default namespace. 2 Restricts traffic to only pods in namespaces that have the label purpose=production . Apply the policy by entering the following command: USD oc apply -f web-allow-prod.yaml Example output networkpolicy.networking.k8s.io/web-allow-prod created Verification Start a web service in the default namespace by entering the following command: USD oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80 Run the following command to create the prod namespace: USD oc create namespace prod Run the following command to label the prod namespace: USD oc label namespace/prod purpose=production Run the following command to create the dev namespace: USD oc create namespace dev Run the following command to label the dev namespace: USD oc label namespace/dev purpose=testing Run the following command to deploy an alpine image in the dev namespace and to start a shell: USD oc run test-USDRANDOM --namespace=dev --rm -i -t --image=alpine -- sh Run the following command in the shell and observe that the request is blocked: # wget -qO- --timeout=2 http://web.default Expected output wget: download timed out Run the following command to deploy an alpine image in the prod namespace and start a shell: USD oc run test-USDRANDOM --namespace=prod --rm -i -t --image=alpine -- sh Run the following command in the shell and observe that the request is allowed: # wget -qO- --timeout=2 http://web.default Expected output <!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> html { color-scheme: light dark; } body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html> 21.2.7. Additional resources Accessing the web console Logging for egress firewall and network policy rules 21.3. Viewing a network policy As a user with the admin role, you can view a network policy for a namespace. 21.3.1. Example NetworkPolicy object The following annotates an example NetworkPolicy object: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017 1 The name of the NetworkPolicy object. 2 A selector that describes the pods to which the policy applies. The policy object can only select pods in the project that defines the NetworkPolicy object. 3 A selector that matches the pods from which the policy object allows ingress traffic. The selector matches pods in the same namespace as the NetworkPolicy. 4 A list of one or more destination ports on which to accept traffic. 21.3.2. Viewing network policies using the CLI You can examine the network policies in a namespace. Note If you log in with a user with the cluster-admin role, then you can view any network policy in the cluster. Prerequisites You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace where the network policy exists. Procedure List network policies in a namespace: To view network policy objects defined in a namespace, enter the following command: USD oc get networkpolicy Optional: To examine a specific network policy, enter the following command: USD oc describe networkpolicy <policy_name> -n <namespace> where: <policy_name> Specifies the name of the network policy to inspect. <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. For example: USD oc describe networkpolicy allow-same-namespace Output for oc describe command Name: allow-same-namespace Namespace: ns1 Created on: 2021-05-24 22:28:56 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: PodSelector: <none> Not affecting egress traffic Policy Types: Ingress Note If you log in to the web console with cluster-admin privileges, you have a choice of viewing a network policy in any namespace in the cluster directly in YAML or from a form in the web console. 21.4. Editing a network policy As a user with the admin role, you can edit an existing network policy for a namespace. 21.4.1. Editing a network policy You can edit a network policy in a namespace. Note If you log in with a user with the cluster-admin role, then you can edit a network policy in any namespace in the cluster. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace where the network policy exists. Procedure Optional: To list the network policy objects in a namespace, enter the following command: USD oc get networkpolicy where: <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. Edit the network policy object. If you saved the network policy definition in a file, edit the file and make any necessary changes, and then enter the following command. USD oc apply -n <namespace> -f <policy_file>.yaml where: <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. <policy_file> Specifies the name of the file containing the network policy. If you need to update the network policy object directly, enter the following command: USD oc edit networkpolicy <policy_name> -n <namespace> where: <policy_name> Specifies the name of the network policy. <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. Confirm that the network policy object is updated. USD oc describe networkpolicy <policy_name> -n <namespace> where: <policy_name> Specifies the name of the network policy. <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. Note If you log in to the web console with cluster-admin privileges, you have a choice of editing a network policy in any namespace in the cluster directly in YAML or from the policy in the web console through the Actions menu. 21.4.2. Example NetworkPolicy object The following annotates an example NetworkPolicy object: kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017 1 The name of the NetworkPolicy object. 2 A selector that describes the pods to which the policy applies. The policy object can only select pods in the project that defines the NetworkPolicy object. 3 A selector that matches the pods from which the policy object allows ingress traffic. The selector matches pods in the same namespace as the NetworkPolicy. 4 A list of one or more destination ports on which to accept traffic. 21.4.3. Additional resources Creating a network policy 21.5. Deleting a network policy As a user with the admin role, you can delete a network policy from a namespace. 21.5.1. Deleting a network policy using the CLI You can delete a network policy in a namespace. Note If you log in with a user with the cluster-admin role, then you can delete any network policy in the cluster. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. You are working in the namespace where the network policy exists. Procedure To delete a network policy object, enter the following command: USD oc delete networkpolicy <policy_name> -n <namespace> where: <policy_name> Specifies the name of the network policy. <namespace> Optional: Specifies the namespace if the object is defined in a different namespace than the current namespace. Example output networkpolicy.networking.k8s.io/default-deny deleted Note If you log in to the web console with cluster-admin privileges, you have a choice of deleting a network policy in any namespace in the cluster directly in YAML or from the policy in the web console through the Actions menu. 21.6. Defining a default network policy for projects As a cluster administrator, you can modify the new project template to automatically include network policies when you create a new project. If you do not yet have a customized template for new projects, you must first create one. 21.6.1. 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: Prerequisites You have access to an OpenShift Container Platform cluster using an account with cluster-admin permissions. Procedure Log in as a user with cluster-admin privileges. Generate the default project template: USD 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: USD oc create -f template.yaml -n openshift-config Edit the project configuration resource using the web console or CLI. Using the web console: Navigate to the Administration Cluster Settings page. Click Configuration to view all configuration resources. Find the entry for Project and click Edit YAML . Using the CLI: Edit the project.config.openshift.io/cluster resource: USD 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. 21.6.2. 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: USD 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: Create a new project: USD oc new-project <project> 1 1 Replace <project> with the name for the project you are creating. Confirm that the network policy objects in the new project template exist in the new project: USD oc get networkpolicy NAME POD-SELECTOR AGE allow-from-openshift-ingress <none> 7s allow-from-same-namespace <none> 7s 21.7. Configuring multitenant isolation with network policy As a cluster administrator, you can configure your network policies to provide multitenant network isolation. Note If you are using the OpenShift SDN network plugin, configuring network policies as described in this section provides network isolation similar to multitenant mode but with network policy mode set. 21.7.1. Configuring multitenant isolation by using network policy You can configure your project to isolate it from pods and services in other project namespaces. Prerequisites Your cluster uses a network plugin that supports NetworkPolicy objects, such as the OVN-Kubernetes network plugin or the OpenShift SDN network plugin with mode: NetworkPolicy set. This mode is the default for OpenShift SDN. You installed the OpenShift CLI ( oc ). You are logged in to the cluster with a user with admin privileges. Procedure Create the following NetworkPolicy objects: A policy named allow-from-openshift-ingress . USD cat << EOF| oc create -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-openshift-ingress spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/ingress: "" podSelector: {} policyTypes: - Ingress EOF Note policy-group.network.openshift.io/ingress: "" is the preferred namespace selector label for OpenShift SDN. You can use the network.openshift.io/policy-group: ingress namespace selector label, but this is a legacy label. A policy named allow-from-openshift-monitoring : USD cat << EOF| oc create -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-openshift-monitoring spec: ingress: - from: - namespaceSelector: matchLabels: network.openshift.io/policy-group: monitoring podSelector: {} policyTypes: - Ingress EOF A policy named allow-same-namespace : USD cat << EOF| oc create -f - kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-same-namespace spec: podSelector: ingress: - from: - podSelector: {} EOF A policy named allow-from-kube-apiserver-operator : USD cat << EOF| oc create -f - 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 EOF For more details, see New kube-apiserver-operator webhook controller validating health of webhook . Optional: To confirm that the network policies exist in your current project, enter the following command: USD oc describe networkpolicy Example output Name: allow-from-openshift-ingress Namespace: example1 Created on: 2020-06-09 00:28:17 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: NamespaceSelector: network.openshift.io/policy-group: ingress Not affecting egress traffic Policy Types: Ingress Name: allow-from-openshift-monitoring Namespace: example1 Created on: 2020-06-09 00:29:57 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: NamespaceSelector: network.openshift.io/policy-group: monitoring Not affecting egress traffic Policy Types: Ingress 21.7.2. steps Defining a default network policy 21.7.3. Additional resources OpenShift SDN network isolation modes

Commands:
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default spec: podSelector: {} ingress: []
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
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-same-namespace spec: podSelector: {} ingress: - from: - podSelector: {}
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
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
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-router spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/ingress: "" 1 podSelector: {} policyTypes: - Ingress
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-hostnetwork spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/host-network: "" podSelector: {} policyTypes: - Ingress
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: test-network-policy spec: podSelector: {} ingress: - from: - podSelector: matchLabels: role: frontend - from: - podSelector: matchLabels: role: backend
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: test-network-policy spec: podSelector: {} ingress: - from: - podSelector: matchExpressions: - {key: role, operator: In, values: [frontend, backend]}
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy1 spec: podSelector: matchLabels: role: db ingress: - from: - podSelector: matchLabels: role: frontend --- apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy2 spec: podSelector: matchLabels: role: client ingress: - from: - podSelector: matchLabels: role: frontend
apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: policy3 spec: podSelector: matchExpressions: - {key: role, operator: In, values: [db, client]} ingress: - from: - podSelector: matchLabels: role: frontend
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017
touch <policy_name>.yaml
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default spec: podSelector: {} policyTypes: - Ingress ingress: []
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-same-namespace spec: podSelector: ingress: - from: - podSelector: {}
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-traffic-pod spec: podSelector: matchLabels: pod: pod-a policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: kubernetes.io/metadata.name: namespace-y
oc apply -f <policy_name>.yaml -n <namespace>
networkpolicy.networking.k8s.io/deny-by-default created
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default namespace: default 1 spec: podSelector: {} 2 ingress: [] 3
oc apply -f deny-by-default.yaml
networkpolicy.networking.k8s.io/deny-by-default created
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-external namespace: default spec: policyTypes: - Ingress podSelector: matchLabels: app: web ingress: - {}
oc apply -f web-allow-external.yaml
networkpolicy.networking.k8s.io/web-allow-external created
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-all-namespaces namespace: default spec: podSelector: matchLabels: app: web 1 policyTypes: - Ingress ingress: - from: - namespaceSelector: {} 2
oc apply -f web-allow-all-namespaces.yaml
networkpolicy.networking.k8s.io/web-allow-all-namespaces created
oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80
oc run test-USDRANDOM --namespace=secondary --rm -i -t --image=alpine -- sh
wget -qO- --timeout=2 http://web.default
<!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> html { color-scheme: light dark; } body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html>
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-prod namespace: default spec: podSelector: matchLabels: app: web 1 policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: purpose: production 2
oc apply -f web-allow-prod.yaml
networkpolicy.networking.k8s.io/web-allow-prod created
oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80
oc create namespace prod
oc label namespace/prod purpose=production
oc create namespace dev
oc label namespace/dev purpose=testing
oc run test-USDRANDOM --namespace=dev --rm -i -t --image=alpine -- sh
wget -qO- --timeout=2 http://web.default
wget: download timed out
oc run test-USDRANDOM --namespace=prod --rm -i -t --image=alpine -- sh
wget -qO- --timeout=2 http://web.default
<!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> html { color-scheme: light dark; } body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html>
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017
oc get networkpolicy
oc describe networkpolicy <policy_name> -n <namespace>
oc describe networkpolicy allow-same-namespace
Name: allow-same-namespace Namespace: ns1 Created on: 2021-05-24 22:28:56 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: PodSelector: <none> Not affecting egress traffic Policy Types: Ingress
oc get networkpolicy
oc apply -n <namespace> -f <policy_file>.yaml
oc edit networkpolicy <policy_name> -n <namespace>
oc describe networkpolicy <policy_name> -n <namespace>
kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-27107 1 spec: podSelector: 2 matchLabels: app: mongodb ingress: - from: - podSelector: 3 matchLabels: app: app ports: 4 - protocol: TCP port: 27017
oc delete networkpolicy <policy_name> -n <namespace>
networkpolicy.networking.k8s.io/default-deny deleted
oc adm create-bootstrap-project-template -o yaml > template.yaml
oc create -f template.yaml -n openshift-config
oc edit project.config.openshift.io/cluster
apiVersion: config.openshift.io/v1 kind: Project metadata: spec: projectRequestTemplate: name: <template_name>
oc edit template <project_template> -n openshift-config
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
oc new-project <project> 1
oc get networkpolicy NAME POD-SELECTOR AGE allow-from-openshift-ingress <none> 7s allow-from-same-namespace <none> 7s
cat << EOF| oc create -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-openshift-ingress spec: ingress: - from: - namespaceSelector: matchLabels: policy-group.network.openshift.io/ingress: "" podSelector: {} policyTypes: - Ingress EOF
cat << EOF| oc create -f - apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: allow-from-openshift-monitoring spec: ingress: - from: - namespaceSelector: matchLabels: network.openshift.io/policy-group: monitoring podSelector: {} policyTypes: - Ingress EOF
cat << EOF| oc create -f - kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: allow-same-namespace spec: podSelector: ingress: - from: - podSelector: {} EOF
cat << EOF| oc create -f - 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 EOF
oc describe networkpolicy
Name: allow-from-openshift-ingress Namespace: example1 Created on: 2020-06-09 00:28:17 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: NamespaceSelector: network.openshift.io/policy-group: ingress Not affecting egress traffic Policy Types: Ingress Name: allow-from-openshift-monitoring Namespace: example1 Created on: 2020-06-09 00:29:57 -0400 EDT Labels: <none> Annotations: <none> Spec: PodSelector: <none> (Allowing the specific traffic to all pods in this namespace) Allowing ingress traffic: To Port: <any> (traffic allowed to all ports) From: NamespaceSelector: network.openshift.io/policy-group: monitoring Not affecting egress traffic Policy Types: Ingress