2.14. Managing traffic in your service mesh

Procedure

1. Set a unique label for the Istio ingress gateway. This setting is required to ensure that the gateway can select the workload. This example uses ingressgateway as the name of the gateway.

   apiVersion: v1
   kind: Service
   metadata:
     name: istio-ingressgateway
     namespace: istio-ingress
   spec:
     type: ClusterIP
     selector:
       istio: ingressgateway
     ports:
     - name: http2
       port: 80
       targetPort: 8080
     - name: https
       port: 443
       targetPort: 8443
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: istio-ingressgateway
     namespace: istio-ingress
   spec:
     selector:
       matchLabels:
         istio: ingressgateway
     template:
       metadata:
         annotations:
           inject.istio.io/templates: gateway
         labels:
           istio: ingressgateway
           sidecar.istio.io/inject: "true" 

   1

   
       spec:
         containers:
         - name: istio-proxy
           image: auto 

   2

   1

   Enable gateway injection by setting the sidecar.istio.io/inject field to "true".

   2

   Set the image field to auto so that the image automatically updates each time the pod starts.

2. Set up roles to allow reading credentials for TLS.

   apiVersion: rbac.authorization.k8s.io/v1
   kind: Role
   metadata:
     name: istio-ingressgateway-sds
     namespace: istio-ingress
   rules:
     - apiGroups: [""]
       resources: ["secrets"]
       verbs: ["get", "watch", "list"]
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: RoleBinding
   metadata:
     name: istio-ingressgateway-sds
     namespace: istio-ingress
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: Role
     name: istio-ingressgateway-sds
   subjects:
   - kind: ServiceAccount
     name: default

3. Grant access to the new gateway from outside the cluster, which is required whenever spec.security.manageNetworkPolicy is set to true.

   apiVersion: networking.k8s.io/v1
   kind: NetworkPolicy
   metadata:
     name: gatewayingress
     namespace: istio-ingress
   spec:
     podSelector:
       matchLabels:
         istio: ingressgateway
     ingress:
       - {}
     policyTypes:
     - Ingress

4. Automatically scale the pod when ingress traffic increases. This example sets the minimum replicas to 2 and the maximum replicas to 5. It also creates another replica when utilization reaches 80%.

   apiVersion: autoscaling/v2
   kind: HorizontalPodAutoscaler
   metadata:
     labels:
       istio: ingressgateway
       release: istio
     name: ingressgatewayhpa
     namespace: istio-ingress
   spec:
     maxReplicas: 5
     metrics:
     - resource:
         name: cpu
         target:
           averageUtilization: 80
           type: Utilization
       type: Resource
     minReplicas: 2
     scaleTargetRef:
       apiVersion: apps/v1
       kind: Deployment
       name: istio-ingressgateway

5. Specify the minimum number of pods that must be running on the node. This example ensures one replica is running if a pod gets restarted on a new node.

   apiVersion: policy/v1
   kind: PodDisruptionBudget
   metadata:
     labels:
       istio: ingressgateway
       release: istio
     name: ingressgatewaypdb
     namespace: istio-ingress
   spec:
     minAvailable: 1
     selector:
       matchLabels:
         istio: ingressgateway

Procedure

1. Create a gateway to accept traffic.

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

      Gateway example gateway.yaml

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

   2. Apply the YAML file.

      $ oc apply -f gateway.yaml

2. Create a VirtualService object to rewrite the host header.

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

      Virtual service example

      apiVersion: networking.istio.io/v1alpha3
      kind: VirtualService
      metadata:
        name: bookinfo
      spec:
        hosts:
        - "*"
        gateways:
        - bookinfo-gateway
        http:
        - match:
          - uri:
              exact: /productpage
          - uri:
              prefix: /static
          - uri:
              exact: /login
          - uri:
              exact: /logout
          - uri:
              prefix: /api/v1/products
          route:
          - destination:
              host: productpage
              port:
                number: 9080

   2. Apply the YAML file.

      $ oc apply -f vs.yaml

3. Test that the gateway and VirtualService have been set correctly.

   1. Set the Gateway URL.

      export GATEWAY_URL=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.host}')

   2. Set the port number. In this example, istio-system is the name of the Service Mesh control plane project.

      export TARGET_PORT=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.port.targetPort}')

   3. Test a page that has been explicitly exposed.

      curl -s -I "$GATEWAY_URL/productpage"

      The expected result is 200.