12.3. Using custom domains for Knative services with Service Mesh

Procedure

1. Create an Istio gateway to accept traffic.

   1. Create a YAML file, and copy the following YAML into it:

      apiVersion: networking.istio.io/v1alpha3
      kind: Gateway
      metadata:
        name: default-gateway
      spec:
        selector:
          istio: ingressgateway
        servers:
        - port:
            number: 80
            name: http
            protocol: HTTP
          hosts:
          - "*"

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   2. Apply the YAML file:

      $ oc apply -f <filename>

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2. Create an Istio VirtualService object to rewrite the host header.

   1. Create a YAML file, and copy the following YAML into it:

      apiVersion: networking.istio.io/v1alpha3
      kind: VirtualService
      metadata:
        name: hello
      spec:
        hosts:
        - custom-ksvc-domain.example.com
        gateways:
        - default-gateway
        http:
        - rewrite:
            authority: hello.default.svc 

      1

      
          route:
          - destination:
              host: hello.default.svc 

      2

      
              port:
                number: 80

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      1 2

      Your Knative service in the format <service_name>.<namespace>.svc.

   2. Apply the YAML file:

      $ oc apply -f <filename>

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3. Create an Istio ServiceEntry object. This is required for OpenShift Serverless because Kourier is outside of the service mesh.

   1. Create a YAML file, and copy the following YAML into it:

      apiVersion: networking.istio.io/v1alpha3
      kind: ServiceEntry
      metadata:
        name: hello.default.svc
      spec:
        hosts:
        - hello.default.svc 

      1

      
        location: MESH_EXTERNAL
        endpoints:
        - address: kourier-internal.knative-serving-ingress.svc
        ports:
        - number: 80
          name: http
          protocol: HTTP
        resolution: DNS

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      1

      Your Knative service in the format <service_name>.<namespace>.svc.

   2. Apply the YAML file:

      $ oc apply -f <filename>

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4. Create an OpenShift Container Platform route that points to the VirtualService object.

   1. Create a YAML file, and copy the following YAML into it:

      apiVersion: route.openshift.io/v1
      kind: Route
      metadata:
        name: hello
        namespace: istio-system 

      1

      
      spec:
        host: custom-ksvc-domain.example.com
        port:
          targetPort: 8080
        to:
          kind: Service
          name: istio-ingressgateway

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Procedure

1. Access the custom domain by using the Host header in a curl request. For example:

   $ curl -H "Host: custom-ksvc-domain.example.com" http://<ip_address>

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   where <ip_address> is the IP address that the OpenShift Container Platform ingress router is exposed to.

   Example output

   Hello OpenShift!

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