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Using Serving with OpenShift ingress sharding

You can use Knative Serving with OpenShift ingress sharding to split ingress traffic based on domains. This allows you to manage and route network traffic to different parts of a cluster more efficiently.

Even with OpenShift ingress sharding in place, OpenShift Serverless traffic is still routed through a single Knative Ingress Gateway and the activator component in the knative-serving project.

For more information about isolating the network traffic, see Using Service Mesh to isolate network traffic with OpenShift Serverless.
Prerequisites

  • You have installed the OpenShift Serverless Operator and Knative Serving.

  • You have cluster administrator permissions on OpenShift Container Platform, or you have cluster or dedicated administrator permissions on Red Hat OpenShift Service on AWS or OpenShift Dedicated.

Configuring OpenShift ingress shards

Before configuring Knative Serving, you must configure OpenShift ingress shards.

Procedure

  • Use a label selector in the IngressController CR to configure OpenShift Serverless to match specific ingress shards with different domains:

    Example IngressController CR
    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: ingress-dev (1)
  namespace: openshift-ingress-operator
spec:
  routeSelector:
    matchLabels:
      router: dev (2)
  domain: "dev.serverless.cluster.example.com" (3)
  # ...
---
apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  name: ingress-prod (4)
  namespace: openshift-ingress-operator
spec:
  routeSelector:
    matchLabels:
      router: prod (5)
  domain: "prod.serverless.cluster.example.com" (6)
  # ...
    1 Name of the first ingress shard.
    2 A label selector to match the ingress-dev shard.
    3 A custom domain for the ingress-dev shard.
    4 Name of the second ingress shard.
    5 A label selector to match the ingress-prod shard.
    6 A custom domain for the ingress-prod shard.

Configuring custom domains in the KnativeServing CR

After configuring OpenShift ingress shards, you must configure Knative Serving to match them.

Procedure

  • In the KnativeServing CR, configure Serving to use the same domains and labels as your ingress shards by adding the spec.config.domain field:

    Example KnativeServing CR
    spec:
  config:
    domain: (1)
      dev.serverless.cluster.example.com: |
        selector:
          router: dev
      prod.serverless.cluster.example.com: |
        selector:
          router: prod
  # ...
    1 These values need to match the values in the ingress shard configuration.

Targeting a specific ingress shard in the Knative Service

After configuring ingress sharding and Knative Serving, you can target a specific ingress shard in your Knative Service resources using a label.

Procedure

  • In your Service CR, add the label selector that matches a specific shard:

    Example Service CR
    apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: hello-dev
  labels:
    router: dev (1)
spec:
  template:
    spec:
      containers:
      - image: docker.io/openshift/hello-openshift
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: hello-prod
  labels:
    router: prod (1)
spec:
  template:
    spec:
      containers:
      - image: docker.io/openshift/hello-openshift
  # ...
    1 The labels must match the configuration in the KnativeServing CR.

Verifying Serving with OpenShift ingress sharding configuration

After configuring ingress sharding, Knative Serving, and your service, you can verify that your service uses the correct route and the selected ingress shard.

Procedure

  1. Print information about the services in the cluster by running the following command:

    $ oc get ksvc
    Example output
    NAME         URL                                                             LATESTCREATED      LATESTREADY        READY   REASON
hello-dev    https://hello-dev-default.dev.serverless.cluster.example.com    hello-dev-00001    hello-dev-00001    True
hello-prod   https://hello-prod-default.prod.serverless.cluster.example.com  hello-prod-00001   hello-prod-00001   True

  2. Verify that your service uses the correct route and the selected ingress shard by running the following command:

    $ oc get route -n knative-serving-ingress -o jsonpath='{range .items[*]}{@.metadata.name}{" "}{@.spec.host}{" "}{@.status.ingress[*].routerName}{"\n"}{end}'
    Example output
    route-19e6628b-77af-4da0-9b4c-1224934b2250-323461616533 hello-prod-default.prod.serverless.cluster.example.com ingress-prod
route-cb5085d9-b7da-4741-9a56-96c88c6adaaa-373065343266 hello-dev-default.dev.serverless.cluster.example.com ingress-dev