If you have a multicluster Gloo Mesh (Gloo Platform APIs) setup, deploy an Istio east-west gateway into each workload cluster. An east-west gateway lets services in one mesh communicate with services in another.

Before you begin

  1. Deploy the Bookinfo sample app.

  2. Save the kubeconfig contexts for your clusters. The examples in this guide assume one management cluster, and two workload clusters that run Istio service meshes.

      export MGMT_CONTEXT=<management-cluster-context>
export REMOTE_CONTEXT1=<remote-cluster1-context>
export REMOTE_CONTEXT2=<remote-cluster2-context>

  3. If you have not already, set environment variables for the Solo distribution of Istio that you want to install. You can find these values in the Istio images built by Solo.io support article.

      # Solo distribution of Istio patch version
# in the format 1.x.x, with no tags
export ISTIO_VERSION=1.25.2
# Repo key for the minor version of the Solo distribution of Istio
# This is the 12-character hash at the end of the repo URL: 'us-docker.pkg.dev/gloo-mesh/istio-<repo-key>'
export REPO_KEY=<repo_key>

# Solo distribution of Istio patch version and Solo tag
# Optionally append other Solo tags as needed
export ISTIO_IMAGE=${ISTIO_VERSION}-solo
# Solo distribution of Istio image repo
export REPO=us-docker.pkg.dev/gloo-mesh/istio-${REPO_KEY}
# Solo distribution of Istio Helm repo
export HELM_REPO=us-docker.pkg.dev/gloo-mesh/istio-helm-${REPO_KEY}

  4. Get the revision that you used for your installation. Typically, this is main for a Helm installation, or gloo for a Gloo Operator installation.

      export REVISION=$(kubectl get pod -l app=istiod -n istio-system -o jsonpath='{.items[0].metadata.labels.istio\.io/rev}')      
echo ${REVISION}

Deploy east-west gateways in each workload cluster

  1. Prepare a Helm values file for the Istio east-west gateway. This sample command downloads an example file, eastwest-gateway.yaml, and updates the environment variables with the values that you previously set. You can further edit the file to provide your own details for production-level settings.

      curl -0L https://raw.githubusercontent.com/solo-io/gloo-mesh-use-cases/main/gloo-mesh-enterprise/istio-install/manual-helm/eastwest-gateway-1.24+.yaml > eastwest-gateway.yaml
envsubst < eastwest-gateway.yaml > eastwest-gateway-values.yaml

  2. Create an east-west gateway in each cluster.

      helm upgrade --install istio-eastwestgateway oci://${HELM_REPO}/gateway \
  --version ${ISTIO_VERSION} \
  --namespace istio-eastwest \
  --create-namespace \
  --kube-context ${REMOTE_CONTEXT1} \
  --wait \
  -f eastwest-gateway-values.yaml

helm upgrade --install istio-eastwestgateway oci://${HELM_REPO}/gateway \
  --version ${ISTIO_VERSION} \
  --namespace istio-eastwest \
  --create-namespace \
  --kube-context ${REMOTE_CONTEXT2} \
  --wait \
  -f eastwest-gateway-values.yaml

  3. Verify that the east-west gateway pods are running and the load balancer service is assigned an external address.

      kubectl get pods,svc -n istio-eastwest --context ${REMOTE_CONTEXT1}
kubectl get pods,svc -n istio-eastwest --context ${REMOTE_CONTEXT2}

    Example output:

      NAME                                     READY   STATUS    RESTARTS   AGE
istio-eastwestgateway-7f6f8f7fc7-ncrzq   1/1     Running   0          11s
istio-eastwestgateway-7f6f8f7fc7-ncrzq   1/1     Running   0          48s
NAME                        TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)                                                                                                      AGE
istio-eastwestgateway       LoadBalancer   10.96.166.166   <externalip>  15021:32343/TCP,80:31685/TCP,443:30877/TCP,31400:31030/TCP,15443:31507/TCP,15012:30668/TCP,15017:30812/TCP   13s

Set up routing across clusters

After you create east-west gateways in each workload cluster, you can then set up cross-cluster routing to your in-mesh apps. The steps in this section use the Bookinfo sample app as an example.

  1. Create a Gloo root trust policy to ensure that services in cluster1 securely communicate with the reviews service in cluster2. The root trust policy sets up the domain and certificates to establish a shared trust model across multiple clusters in your service mesh.

      kubectl apply --context $MGMT_CONTEXT -f - <<EOF
apiVersion: admin.gloo.solo.io/v2
kind: RootTrustPolicy
metadata:
  name: root-trust
  namespace: gloo-mesh
spec:
  config:
    mgmtServerCa:
      generated: {}
EOF

  2. Restart istiod and the sample apps that you deployed earlier to apply the updated certificates.

      kubectl rollout restart deployment istiod-${REVISION} -n istio-system --context ${REMOTE_CONTEXT1}
kubectl rollout restart deployment istiod-${REVISION} -n istio-system --context ${REMOTE_CONTEXT2}
kubectl rollout restart deployment details-v1 productpage-v1 ratings-v1 reviews-v1 reviews-v2 -n bookinfo --context ${REMOTE_CONTEXT1}
kubectl rollout restart deployment ratings-v1 reviews-v3 -n bookinfo --context ${REMOTE_CONTEXT2}
kubectl rollout restart deployment httpbin -n httpbin --context ${REMOTE_CONTEXT1}
kubectl rollout restart deployment helloworld-v1 helloworld-v2 -n helloworld --context ${REMOTE_CONTEXT1}
kubectl rollout restart deployment helloworld-v3 helloworld-v4 -n helloworld --context ${REMOTE_CONTEXT2}

  3. Create a virtual destination resource and define a unique hostname that in-mesh gateways can use to send requests to the reviews app. This virtual destination is configured to listen for incoming traffic on the internal-only, arbitrary hostname reviews.mesh.internal.com:8080.

      kubectl apply --context $MGMT_CONTEXT -n bookinfo -f- <<EOF
apiVersion: networking.gloo.solo.io/v2
kind: VirtualDestination
metadata:
  name: reviews-vd
  namespace: bookinfo
spec:
  hosts:
  # Arbitrary, internal-only hostname assigned to the endpoint
  - reviews.mesh.internal.com
  ports:
  - number: 9080
    protocol: HTTP
  services:
    - labels:
        app: reviews
EOF

  4. Create a route table that defines how east-west requests within your mesh are routed from the productpage service to the reviews-vd virtual destination. When you apply this route table, requests from productpage to /reviews now route to one of the three reviews versions across clusters. The east-west gateway in your mesh does the work of taking requests made to the reviews.bookinfo.svc.cluster.local hostname and routing them to the reviews.mesh.internal.com virtual destination hostname that you specified in the previous step.

      kubectl apply --context $MGMT_CONTEXT -n bookinfo -f- <<EOF
apiVersion: networking.gloo.solo.io/v2
kind: RouteTable
metadata:
  name: bookinfo-east-west
  namespace: bookinfo
spec:
  hosts:
    - 'reviews.bookinfo.svc.cluster.local'
  workloadSelectors:
    - selector:
        labels:
          app: productpage
  http:
    - name: reviews
      matchers:
      - uri:
          prefix: /reviews
      forwardTo:
        destinations:
          - ref:
              name: reviews-vd
            kind: VIRTUAL_DESTINATION
            port:
              number: 9080
      labels: 
        route: reviews
EOF

  5. In your terminal, open the Bookinfo product page from your local host.

    1. Enable port-forwarding on the product page deployment.
        kubectl --context ${REMOTE_CONTEXT1} -n bookinfo port-forward deployment/productpage-v1 9080:9080
    2. Open your browser to http://localhost:9080/productpage?u=normal.

  6. Refresh the page a few times again. Now, the red stars for reviews-v3 are shown in the book reviews.

    Figure: Bookinfo product page UI with red star reviews
    Figure: Bookinfo product page UI with red star reviews

    Bookinfo services in cluster1 are now successfully accessing the Bookinfo services in cluster2!

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