镜像
此任务演示了 Istio 的流量镜像功能。
流量镜像,也称为影子流量,是一个以尽可能低的风险为生产带来变化的强大的功能。镜像会将实时流量的副本发送到镜像服务。镜像流量发生在主服务的关键请求路径之外。
在此任务中,您将首先强制所有流量到 v1
测试服务。然后,您将使用规则将一部分流量镜像到 v2
。
开始之前
按照安装指南中的说明设置 Istio 。
首先部署启用了访问日志的两个版本的 httpbin 服务:
httpbin-v1:
cat <<EOF | istioctl kube-inject -f - | kubectl create -f - apiVersion: extensions/v1beta1 kind: Deployment metadata: name: httpbin-v1 spec: replicas: 1 template: metadata: labels: app: httpbin version: v1 spec: containers: - image: docker.io/kennethreitz/httpbin imagePullPolicy: IfNotPresent name: httpbin command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:8080", "httpbin:app"] ports: - containerPort: 8080 EOF
httpbin-v2:
cat <<EOF | istioctl kube-inject -f - | kubectl create -f - apiVersion: extensions/v1beta1 kind: Deployment metadata: name: httpbin-v2 spec: replicas: 1 template: metadata: labels: app: httpbin version: v2 spec: containers: - image: docker.io/kennethreitz/httpbin imagePullPolicy: IfNotPresent name: httpbin command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:8080", "httpbin:app"] ports: - containerPort: 8080 EOF
httpbin Kubernetes service:
cat <<EOF | kubectl create -f - apiVersion: v1 kind: Service metadata: name: httpbin labels: app: httpbin spec: ports: - name: http port: 8080 selector: app: httpbin EOF
启动
sleep
服务,这样您就可以使用curl
来提供负载:sleep service:
cat <<EOF | istioctl kube-inject -f - | kubectl create -f - apiVersion: extensions/v1beta1 kind: Deployment metadata: name: sleep spec: replicas: 1 template: metadata: labels: app: sleep spec: containers: - name: sleep image: tutum/curl command: ["/bin/sleep","infinity"] imagePullPolicy: IfNotPresent EOF
创建默认路由策略
默认情况下,Kubernetes 在 httpbin
服务的两个版本之间进行负载均衡。在此步骤中,您将更改该行为,以便所有流量都转到 v1
。
创建一个默认路由规则,将所有流量路由到服务的
v1
:cat <<EOF | istioctl create -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: httpbin spec: hosts: - httpbin http: - route: - destination: host: httpbin subset: v1 weight: 100 --- apiVersion: networking.istio.io/v1alpha3 kind: DestinationRule metadata: name: httpbin spec: host: httpbin subsets: - name: v1 labels: version: v1 - name: v2 labels: version: v2 EOF
注意:如果您已经安装/配置 Istio 并启用 TLS 双向认证,您必须增加 TLSSettings.TLSmode,
mode: ISTIO_MUTUAL
。如 TLSSettings 参考中所述。现在所有流量已经都转到
httpbin v1
服务。向服务发送一些流量:
$ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}) $ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8080/headers' | python -m json.tool { "headers": { "Accept": "*/*", "Content-Length": "0", "Host": "httpbin:8080", "User-Agent": "curl/7.35.0", "X-B3-Sampled": "1", "X-B3-Spanid": "eca3d7ed8f2e6a0a", "X-B3-Traceid": "eca3d7ed8f2e6a0a", "X-Ot-Span-Context": "eca3d7ed8f2e6a0a;eca3d7ed8f2e6a0a;0000000000000000" } }
查看
httpbin
pods 的v1
和v2
日志。您可以看到v1
的访问日志和v2
为 <none> 的日志:$ export V1_POD=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..metadata.name}) $ kubectl logs -f $V1_POD -c httpbin 127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
$ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name}) $ kubectl logs -f $V2_POD -c httpbin <none>
镜像流量到 v2
改变路由规则将流量镜像到 v2:
cat <<EOF | istioctl replace -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: httpbin spec: hosts: - httpbin http: - route: - destination: host: httpbin subset: v1 weight: 100 mirror: host: httpbin subset: v2 EOF
此路由规则将 100% 的流量发送到
v1
。最后一节指定镜像到httpbin v2
服务。当流量被镜像时,请求将通过其主机/授权报头发送到镜像服务附上-shadow
。例如,将cluster-1
变为cluster-1-shadow
。此外,重点注意这些请求被镜像为"即发即弃”,这意味着这些响应是被丢弃的。
发送流量:
$ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8080/headers' | python -m json.tool
现在,您可以查看
v1
和v2
的访问日志记录。在v2
中创建的请求实际上也通过了v1
。$ kubectl logs -f $V1_POD -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 -f $V2_POD -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
删除规则:
$ istioctl delete virtualservice httpbin $ istioctl delete destinationrule httpbin
关闭 httpbin 服务和客户端:
$ kubectl delete deploy httpbin-v1 httpbin-v2 sleep $ kubectl delete svc httpbin
如果您不打算探索任何后续任务,请参阅 Bookinfo 清理 的说明去关闭应用程序。
See also
介绍更安全,低风险的部署和发布到生产。
Istio v1alpha3 路由 API 介绍,动机及其设计原则。
描述基于 Istio 的 Bookinfo 示例的简单场景。
描述基于 Istio Bookinfo 示例的简单场景。
使用 Istio 创建自动缩放的金丝雀部署。
在 Istio 中配置从网格内访问外部服务的流量路由。