10.6.2　部署示例应用

为了验证上述Envoy过滤器生效，类似于前面章节，按照以下步骤部署示例应用。首先部署一个用于返回HTTP请求响应的应用示例（可以参考本书源码文件envoyf ilter文件夹中的httpecho.yaml），对应的资源定义如下所示：

apiVersion: v1
kind: Service
metadata:
  name: httpecho
  labels:
    app: httpecho
spec:
  ports:
  - name: http
    port: 5678
  selector:
    app: httpecho
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: httpecho-v1
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: httpecho
        version: v1
    spec:
      containers:
      - image: solsson/http-echo
        imagePullPolicy: IfNotPresent
        name: httpecho
        env:
          - name: PORT
            value: "5678"
        ports:
        - containerPort: 5678

为了调用上述httpecho服务，需要部署一个请求客户端，即前面章节中用到的sleep应用，执行如下命令：

kubectl apply -f sleep.yaml

等待应用容器完全启动之后，选择其中的sleep容器例如sleep-xxxx，通过执行如下类似命令登录到容器中：

$ kubectl exec -it sleep-7ffd5cc988-8j8z4 sh
Defaulting container name to sleep.
Use 'kubectl describe pod/sleep-7ffd5cc988-8j8z4 -n default' to see all of the containers in this pod.

此时，可以通过curl命令访问httpecho服务，并检查返回的结果中是否包含了上述Envoy过滤器定义的请求响应头信息，如下所示：

$ curl -v httpecho:5678
* Rebuilt URL to: httpecho:5678/
*   Trying 172.21.3.204...
* TCP_NODELAY set
* Connected to httpecho (172.21.3.204) port 5678 (#0)
> GET / HTTP/1.1
> Host: httpecho:5678
> User-Agent: curl/7.60.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: application/json; charset=utf-8
< content-length: 619
< etag: W/"26b-vEElEBBPjhJ4OwB0VpbnNz6mf74"
< date: Tue, 19 Feb 2019 05:47:48 GMT
< x-envoy-upstream-service-time: 3
< server: envoy
< response-body-size: 619  //添加的一个请求头和正文的大小
<
{
  "path": "/",
  "headers": {
    "host": "httpecho:5678",
    "user-agent": "curl/7.60.0",
    "accept": "*/*",
    "x-forwarded-proto": "http",
    "x-request-id": "d42eb93f-f0ee-9892-9bd6-8e1eb15f60dd",
    "x-b3-traceid": "8f9b0ff4daa8aa15",
    "x-b3-spanid": "8f9b0ff4daa8aa15",
    "x-b3-sampled": "1",
    "mykey": "myvalue",  //添加的一个自定义的请求头
    "content-length": "0"
  },
  "method": "GET",
  "body": "",
  "fresh": false,
  "hostname": "httpecho",
  "ip": "::ffff:127.0.0.1",
  "ips": [],
  "protocol": "http",
  "query": {},
  "subdomains": [],
  "xhr": false,
  "os": {
    "hostname": "httpecho-v1-d8f665dc5-vm7pv"
  }

由此可见，Envoy过滤器配置文件定义了HTTP过滤器，而HTTP过滤器会在Envoy监听器上执行。Lua脚本定义了过滤器的行为，Lua脚本将自身注册到envoy_on_request与envoy_on_response两个事件上，这意味着针对传入请求与传出流量它都会调用过滤器。