Alibaba Cloud Service Mesh:Use graceful shutdown to prevent traffic loss

Step 1: Enable graceful shutdown

apiVersion: istio.alibabacloud.com/v1
kind: IstioGateway
metadata:
  name: ingressgateway
  namespace: istio-system
spec:
  gatewayType: ingress
  serviceAnnotations:
    service.beta.kubernetes.io/alibaba-cloud-loadbalancer-connection-drain: 'on'          # Enables connection draining for the load balancer, which implements graceful shutdown.
    service.beta.kubernetes.io/alibaba-cloud-loadbalancer-connection-drain-timeout: '10'  # The connection draining timeout period, in seconds. Valid values: 10 to 30.
...

apiVersion: istio.alibabacloud.com/v1
kind: IstioGateway
metadata:
  annotations:
    # For CLB and NLB gateways, the valid range is [10, 890].
    # For ClusterIP and NodePort gateways, there is no upper limit.
    asm.alibabacloud.com/gateway-drain-timeout-seconds: "30"
  name: ingressgateway
  namespace: istio-system
...

Step 2: Deploy a sample application

1. Connect to the ACK cluster by using kubectl. For more information, see Obtain the kubeconfig file of a cluster and use kubectl to connect to the cluster.

2. Create a file named httpbin.yaml with the following content.

   httpbin.yaml

   apiVersion: v1
   kind: ServiceAccount
   metadata:
     name: httpbin
   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: httpbin
     labels:
       app: httpbin
       service: httpbin
   spec:
     ports:
     - name: http
       port: 8000
       targetPort: 80
     selector:
       app: httpbin
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: httpbin
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: httpbin
         version: v1
     template:
       metadata:
         labels:
           app: httpbin
           version: v1
       spec:
         serviceAccountName: httpbin
         containers:
         - image: docker.io/kennethreitz/httpbin
           imagePullPolicy: IfNotPresent
           name: httpbin
           ports:
           - containerPort: 80

3. Deploy the httpbin application.

   kubectl apply -f httpbin.yaml -n default

Step 3: Create a VirtualService and a Gateway

1. Create a VirtualService.

   1. Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.

   2. On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose Traffic Management Center > VirtualService. On the page that appears, click Create from YAML.

   3. On the Create page, select a Namespaces and a Scenario Template, paste the following YAML configuration, and then click Create.

      apiVersion: networking.istio.io/v1beta1
      kind: VirtualService
      metadata:
        name: httpbin
        namespace: default
      spec:
        gateways:
          - httpbin-gateway
        hosts:
          - '*'
        http:
          - route:
              - destination:
                  host: httpbin
                  port:
                    number: 8000

2. Create a Gateway.

   1. On the details page of the ASM instance, choose ASM Gateways > Gateway in the left-side navigation pane. On the page that appears, click Create from YAML.

   2. On the Create page, select a Namespaces and a Scenario Template, paste the following YAML configuration, and then click Create.

      apiVersion: networking.istio.io/v1beta1
      kind: Gateway
      metadata:
        name: httpbin-gateway
        namespace: default
      spec:
        selector:
          istio: ingressgateway
        servers:
          - hosts:
              - '*'
            port:
              name: http
              number: 80
              protocol: HTTP

3. Verify the routing configuration.

   1. Obtain the address of the ASM ingress gateway. For more information, see Create an ingress gateway.

   2. In the address bar of your browser, enter http://<ASM ingress gateway address>.

      The httpbin.org homepage appears in your browser, displaying the title httpbin.org and the description A simple HTTP Request & Response Service. This confirms that the VirtualService and Gateway are configured correctly.

Step 4: Verify the effect of graceful shutdown

1. Download and install the version of the lightweight stress testing tool hey that is compatible with your operating system. For more information, see hey.

2. Scale-in the ASM ingress gateway.

   1. Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.

   2. On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose ASM Gateways > Ingress Gateway.

   3. On the Ingress Gateway page, find the target gateway and click View YAML in the Actions column.

   4. In the Edit dialog box, set the value of the replicaCount parameter to 1 and click OK.

3. Run the following command to send 50,000 requests to the httpbin application with a concurrency of 200, and compare the traffic loss before and after you enable graceful shutdown.

   hey -c 200 -n 50000 -disable-keepalive http://<ASM ingress gateway address>/

   Type	Result analysis
   Graceful shutdown disabled	The following output is returned: Status code distribution: [200] 49747 responses Error distribution: [253] Get "http://47.55.2xx.xx": dial tcp 47.55.2xx.xx:80: connect: connection refused Only 49,747 of the 50,000 requests returned a 200 status code, indicating that minor traffic loss occurred.
   Graceful shutdown enabled	The following output is returned: ............ Status code distribution: [200] 50000 responses All 50,000 requests returned a 200 status code, indicating that no traffic loss occurred.