Alibaba Cloud Service Mesh:Shift TCP traffic between application versions

Deploy the tcp-echo Deployments

1. Log on to the ACK console. In the left-side navigation pane, click Clusters.

2. On the Clusters page, click the name of your cluster. In the left-side navigation pane, choose Workloads > Deployments.

3. At the top of the Deployments page, select a namespace from the Namespace drop-down list, and click Create from YAML.

4. Select Custom from the Sample Template drop-down list, paste the following YAML into the Template editor, and click Create. This YAML creates two Deployments. Each runs the tcp-echo-server image on port 9000 but with a different prefix argument (one for v1, two for v2). Both Deployments share the app: tcp-echo label so that a single Service can route to either version. After creation, both Deployments appear on the Deployments page.

   Show the YAML code

      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: tcp-echo-v1
      spec:
        replicas: 1
        selector:
          matchLabels:
            app: tcp-echo
            version: v1
        template:
          metadata:
            labels:
              app: tcp-echo
              version: v1
          spec:
            containers:
            - name: tcp-echo
              image: docker.io/istio/tcp-echo-server:1.1
              imagePullPolicy: IfNotPresent
              args: [ "9000", "one" ]
              ports:
              - containerPort: 9000
      ---
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: tcp-echo-v2
      spec:
        replicas: 1
        selector:
          matchLabels:
            app: tcp-echo
            version: v2
        template:
          metadata:
            labels:
              app: tcp-echo
              version: v2
          spec:
            containers:
            - name: tcp-echo
              image: docker.io/istio/tcp-echo-server:1.1
              imagePullPolicy: IfNotPresent
              args: [ "9000", "two" ]
              ports:
              - containerPort: 9000

Create the tcp-echo Service

1. On the cluster details page, choose Network > Services in the left-side navigation pane.

2. Select the same namespace, and click Create.

3. In the Create Service dialog box, configure the following parameters and click OK. After creation, the tcp-echo Service appears on the Services page.

   Parameter	Value
   Name	tcp-echo
   Service Type	Select a type based on how you want to expose the service. Valid values: Cluster IP, Node Port, and Server Load Balancer.
   Backend	Set Name to app and Value to tcp-echo-v1. Both v1 and v2 Deployments share the app: tcp-echo label, so the Service routes to both regardless of which Deployment you specify here.
   Port Mapping	Set Name to tcp, Service Port and Container Port to 9000, and Protocol to TCP.

Create an Istio gateway

An Istio gateway defines the external entry point for TCP connections. The following configuration listens on port 31400 and forwards connections into the mesh.

1. In the left-side navigation pane, choose ASM Gateways > Gateway. Click Create from YAML.

2. Select default from the Namespace drop-down list, paste the following YAML, and click Create.

      apiVersion: networking.istio.io/v1alpha3
      kind: Gateway
      metadata:
        name: tcp-echo-gateway
      spec:
        selector:
          istio: ingressgateway    # Use the default ingress gateway
        servers:
        - port:
            number: 31400          # External-facing TCP port
            name: tcp
            protocol: TCP
          hosts:
          - "*"                    # Accept connections from any host

Create a destination rule

A destination rule maps pod labels to named subsets that the virtual service references for routing decisions.

1. In the left-side navigation pane, choose Traffic Management Center > DestinationRule. Click Create from YAML.

2. Select default from the Namespace drop-down list, paste the following YAML, and click Create.

      apiVersion: networking.istio.io/v1alpha3
      kind: DestinationRule
      metadata:
        name: tcp-echo-destination
      spec:
        host: tcp-echo             # Matches the Kubernetes Service name
        subsets:
        - name: v1
          labels:
            version: v1            # Selects pods with label version=v1
        - name: v2
          labels:
            version: v2            # Selects pods with label version=v2

Create a virtual service

A virtual service contains the routing logic. The following configuration sends 100% of TCP traffic on port 31400 to the v1 subset. You will update the weights in a later step to shift traffic to v2.

1. In the left-side navigation pane, choose Traffic Management Center > VirtualService. Click Create from YAML.

2. Select default from the Namespace drop-down list, paste the following YAML, and click Create.

      apiVersion: networking.istio.io/v1alpha3
      kind: VirtualService
      metadata:
        name: tcp-echo
      spec:
        hosts:
        - "*"
        gateways:
        - tcp-echo-gateway          # Bind to the gateway created above
        tcp:
        - match:
          - port: 31400             # Match traffic arriving on this port
          route:
          - destination:
              host: tcp-echo        # Target the tcp-echo Kubernetes Service
              port:
                number: 9000
              subset: v1            # Send all traffic to v1