Using Service Mesh with OpenShift Serverless enables developers to configure additional networking and routing options that are not supported when using OpenShift Serverless with the default Kourier implementation. These options include setting custom domains, using TLS certificates, and using JSON Web Token authentication.

Procedure
  1. Add the default namespace to the ServiceMeshMemberRoll as a member:

    apiVersion: maistra.io/v1
    kind: ServiceMeshMemberRoll
    metadata:
      name: default
      namespace: istio-system
    spec:
      members:
        - default

    Adding sidecar injection to Pods in system namespaces such as knative-serving and knative-serving-ingress is not supported.

  2. Create a network policy that permits traffic flow from Knative system Pods to Knative services:

    1. Add the serving.knative.openshift.io/system-namespace=true label to the knative-serving namespace:

      $ oc label namespace knative-serving serving.knative.openshift.io/system-namespace=true
    2. Add the serving.knative.openshift.io/system-namespace=true label to the knative-serving-ingress namespace:

      $ oc label namespace knative-serving-ingress serving.knative.openshift.io/system-namespace=true
    3. Copy the following NetworkPolicy resource into a YAML file:

      apiVersion: networking.k8s.io/v1
      kind: NetworkPolicy
      metadata:
        name: allow-from-serving-system-namespace
        namespace: default
      spec:
        ingress:
        - from:
          - namespaceSelector:
              matchLabels:
                serving.knative.openshift.io/system-namespace: "true"
        podSelector: {}
        policyTypes:
        - Ingress
    4. Apply the NetworkPolicy resource:

      $ oc apply -f <filename>

Enabling sidecar injection for a Knative service

You can add an annotation to the Service resource YAML file to enable sidecar injection for a Knative service.

Procedure
  1. Add the sidecar.istio.io/inject="true" annotation to the Service resource:

    apiVersion: serving.knative.dev/v1
    kind: Service
    metadata:
      name: hello-example-1
    spec:
      template:
        metadata:
          annotations:
            sidecar.istio.io/inject: "true" (1)
        spec:
          containers:
          - image: docker.io/openshift/hello-openshift
            name: container
    1 Add the sidecar.istio.io/inject="true" annotation.
  2. Apply the Service resource YAML file:

    $ oc apply -f <filename>

Additional resources