流量鏡像

此任務示範 Istio 的流量鏡像功能。

流量鏡像，也稱為影子化，是一個強大的概念，可讓功能團隊以盡可能低的風險將變更帶入生產環境。鏡像將即時流量的副本傳送到鏡像服務。鏡像流量發生在主要服務的關鍵請求路徑之外。

在此任務中，您將首先強制所有流量到測試服務的 v1。然後，您將套用規則以將部分流量鏡像到 v2。

開始之前

1. 請按照安裝指南設定 Istio。

2. 首先，部署兩個版本的 httpbin 服務，並啟用存取日誌記錄。

   1. 部署 httpbin-v1

      $ kubectl create -f - <<EOF
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: httpbin-v1
      spec:
        replicas: 1
        selector:
          matchLabels:
            app: httpbin
            version: v1
        template:
          metadata:
            labels:
              app: httpbin
              version: v1
          spec:
            containers:
            - image: docker.io/kennethreitz/httpbin
              imagePullPolicy: IfNotPresent
              name: httpbin
              command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
              ports:
              - containerPort: 80
      EOF
      

   2. 部署 httpbin-v2

      $ kubectl create -f - <<EOF
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: httpbin-v2
      spec:
        replicas: 1
        selector:
          matchLabels:
            app: httpbin
            version: v2
        template:
          metadata:
            labels:
              app: httpbin
              version: v2
          spec:
            containers:
            - image: docker.io/kennethreitz/httpbin
              imagePullPolicy: IfNotPresent
              name: httpbin
              command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
              ports:
              - containerPort: 80
      EOF
      

   3. 部署 httpbin Kubernetes 服務

      $ kubectl create -f - <<EOF
      apiVersion: v1
      kind: Service
      metadata:
        name: httpbin
        labels:
          app: httpbin
      spec:
        ports:
        - name: http
          port: 8000
          targetPort: 80
        selector:
          app: httpbin
      EOF
      

3. 部署 curl 工作負載，您將使用它來向 httpbin 服務發送請求

   $ cat <<EOF | kubectl create -f -
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: curl
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: curl
     template:
       metadata:
         labels:
           app: curl
       spec:
         containers:
         - name: curl
           image: curlimages/curl
           command: ["/bin/sleep","3650d"]
           imagePullPolicy: IfNotPresent
   EOF
   

建立預設路由策略

預設情況下，Kubernetes 會在 httpbin 服務的兩個版本之間進行負載平衡。在此步驟中，您將更改此行為，使所有流量都導向 v1。

1. 建立預設路由規則，將所有流量導向服務的 v1 版本

   Istio APIs Gateway API

   $ kubectl apply -f - <<EOF
   apiVersion: networking.istio.io/v1
   kind: VirtualService
   metadata:
     name: httpbin
   spec:
     hosts:
   - httpbin
     http:
     - route:
   - destination:
       host: httpbin
       subset: v1
     weight: 100
   ---
   apiVersion: networking.istio.io/v1
   kind: DestinationRule
   metadata:
     name: httpbin
   spec:
     host: httpbin
     subsets:
     - name: v1
   labels:
     version: v1
     - name: v2
   labels:
     version: v2
   EOF
   

2. 現在，所有流量都已導向 httpbin:v1，向服務發送一個請求

   $ kubectl exec deploy/curl -c curl -- curl -sS http://httpbin:8000/headers
   {
     "headers": {
       "Accept": "*/*",
       "Content-Length": "0",
       "Host": "httpbin:8000",
       "User-Agent": "curl/7.35.0",
       "X-B3-Parentspanid": "57784f8bff90ae0b",
       "X-B3-Sampled": "1",
       "X-B3-Spanid": "3289ae7257c3f159",
       "X-B3-Traceid": "b56eebd279a76f0b57784f8bff90ae0b",
       "X-Envoy-Attempt-Count": "1",
       "X-Forwarded-Client-Cert": "By=spiffe://cluster.local/ns/default/sa/default;Hash=20afebed6da091c850264cc751b8c9306abac02993f80bdb76282237422bd098;Subject=\"\";URI=spiffe://cluster.local/ns/default/sa/default"
     }
   }
   

3. 檢查 httpbin-v1 和 httpbin-v2 Pod 的日誌。您應該會看到 v1 的存取日誌條目，而 v2 則沒有。

   $ kubectl logs deploy/httpbin-v1 -c httpbin
   127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
   

   $ kubectl logs deploy/httpbin-v2 -c httpbin
   <none>
   

將流量鏡像到 httpbin-v2

1. 更改路由規則以鏡像流量到 httpbin-v2

   Istio APIs Gateway API

   $ kubectl apply -f - <<EOF
   apiVersion: networking.istio.io/v1
   kind: VirtualService
   metadata:
     name: httpbin
   spec:
     hosts:
   - httpbin
     http:
     - route:
   - destination:
       host: httpbin
       subset: v1
     weight: 100
   mirror:
     host: httpbin
     subset: v2
   mirrorPercentage:
     value: 100.0
   EOF
   

   此路由規則將 100% 的流量發送到 v1。最後一段指定您要將 100% 的相同流量鏡像（即同時發送）到 httpbin:v2 服務。當流量被鏡像時，請求會被發送到鏡像服務，其 Host/Authority 標頭會附加 -shadow。例如，cluster-1 會變成 cluster-1-shadow。

   另外，重要的一點是，這些請求是以「發送後不理」的方式鏡像的，這表示回應會被丟棄。

   您可以使用 mirrorPercentage 欄位下的 value 欄位來鏡像一部分流量，而不是鏡像所有請求。如果此欄位不存在，則所有流量都將被鏡像。

2. 發送流量

   $ kubectl exec deploy/curl -c curl -- curl -sS http://httpbin:8000/headers
   

   現在，您應該會看到 v1 和 v2 的存取日誌。在 v2 中建立的存取日誌是實際發送到 v1 的鏡像請求。

   $ kubectl logs deploy/httpbin-v1 -c httpbin
   127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
   127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
   

   $ kubectl logs deploy/httpbin-v2 -c httpbin
   127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 361 "-" "curl/7.35.0"
   

清理

1. 移除規則

   Istio APIs Gateway API

   $ kubectl delete virtualservice httpbin
   $ kubectl delete destinationrule httpbin
   

2. 刪除 httpbin 和 curl 部署以及 httpbin 服務

   $ kubectl delete deploy httpbin-v1 httpbin-v2 curl
   $ kubectl delete svc httpbin