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.
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:
ImportantTo allow ingress connections from
hostNetwork
pods in the same namespace, you need to apply theallow-from-hostnetwork
policy together with theallow-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 aNetworkPolicy
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 previous 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 thenamespaceSelector
or an emptypodSelector
, 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 multipleingress
oregress
rules, than multiple network policies with subsets ofingress
oregress
rules. Every
ingress
oregress
rule based on thepodSelector
ornamespaceSelector
spec generates the number of OVS flows proportional tonumber of pods selected by network policy + number of pods selected by ingress or egress rule
. Therefore, it is preferable to use thepodSelector
ornamespaceSelector
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 sameingress
oregress
rules for different network policies, it might be more efficient to create one network policy with a commonspec.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. Next steps
21.1.5. Additional resources
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.
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 withmode: 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:$ 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 innamespace-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:
$ 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
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.
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 withmode: 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 thedeny-by-default.yaml
file:kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default namespace: default 1 spec: podSelector: {} 2 ingress: [] 3
Apply the policy by entering the following command:
$ 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
.
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 withmode: 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:
$ 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
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 withmode: 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
NoteBy 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:
$ 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:$ oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80
Run the following command to deploy an
alpine
image in thesecondary
namespace and to start a shell:$ oc run test-$RANDOM --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
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 withmode: 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 theweb-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
Apply the policy by entering the following command:
$ 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:$ oc run web --namespace=default --image=nginx --labels="app=web" --expose --port=80
Run the following command to create the
prod
namespace:$ oc create namespace prod
Run the following command to label the
prod
namespace:$ oc label namespace/prod purpose=production
Run the following command to create the
dev
namespace:$ oc create namespace dev
Run the following command to label the
dev
namespace:$ oc label namespace/dev purpose=testing
Run the following command to deploy an
alpine
image in thedev
namespace and to start a shell:$ oc run test-$RANDOM --namespace=dev --rm -i -t --image=alpine -- sh
Run the following command in the shell and observe that the request is blocked:
# wget -qO- --timeout=2 http://web.default
Expected output
wget: download timed out
Run the following command to deploy an
alpine
image in theprod
namespace and start a shell:$ oc run test-$RANDOM --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
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.
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:
$ oc get networkpolicy
Optional: To examine a specific network policy, enter the following command:
$ 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:
$ oc describe networkpolicy allow-same-namespace
Output for
oc describe
commandName: 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
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.
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 withmode: 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:
$ 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.
$ 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:
$ 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.
$ 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.
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
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.
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 withmode: 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:
$ 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
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:
$ 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:
-
Navigate to the Administration
Cluster Settings page. - Click Configuration to view all configuration resources.
- Find the entry for Project and click Edit YAML.
-
Navigate to the Administration
Using the CLI:
Edit the
project.config.openshift.io/cluster
resource:$ oc edit project.config.openshift.io/cluster
Update the
spec
section to include theprojectRequestTemplate
andname
parameters, and set the name of your uploaded project template. The default name isproject-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 withmode: 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 isproject-request
.In the template, add each
NetworkPolicy
object as an element to theobjects
parameter. Theobjects
parameter accepts a collection of one or more objects.In the following example, the
objects
parameter collection includes severalNetworkPolicy
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:
$ 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:
$ 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.
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 withmode: 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
.$ 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
Notepolicy-group.network.openshift.io/ingress: ""
is the preferred namespace selector label for OpenShift SDN. You can use thenetwork.openshift.io/policy-group: ingress
namespace selector label, but this is a legacy label.A policy named
allow-from-openshift-monitoring
:$ 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
:$ 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
:$ 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:
$ 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