Ambassador系列-02-Module模塊

Ambassador的全局配置，可以通過Module模塊配置Ambassador的一些全局的配置參數。當前只有兩種Module模塊：

ambassador：配置全局的系統參數。
tls：配置tls參數

Module可以以CRDs方式定義。

---
apiVersion: getambassador.io/v1
kind: Module
metadata:
  name: ambassador
spec:
  config:
    enable_grpc_web: true
---
apiVersion: getambassador.io/v1
kind: Module
metadata:
  name: tls
spec:
  config:
    server:
      enabled: true
      secret: ambassador-certs
      redirect_cleartext_from: 8080

也可以以註解的方式定義，可以定義在任何Service中，但通常定義在Ambassador Service中，定義在Service中，也是全局生效。

---
apiVersion: v1
kind: Service
metadata:
  name: ambassador
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: getambassador.io/v1
      kind: Module
      name: ambassador
      config:
        enable_grpc_web: True
      ---
      apiVersion: getambassador.io/v1
      kind: Module
      name: tls
      config:
        server:
          enabled: true
          secret: ambassador-certs
          redirect_cleartext_from: 8080
spec:
  type: LoadBalancer
  externalTrafficPolicy: Local
  ports:
   - name: http
     port: 80
     targetPort: 8080
   - name: https
     port: 443
     targetPort: 8443
  selector:
    service: ambassador

實驗環境接上節Ambassador系列-01-介紹、安裝和使用。

下面舉一例子，Ambassador支持在每個請求上運行內聯Lua腳本的功能。例如添加自定義的報文頭。

vi ambassador-module.yaml
---
apiVersion: getambassador.io/v1
kind: Module
metadata:
  name: ambassador
spec:
  config:
    lua_scripts: |
      function envoy_on_response(response_handle)
        response_handle:headers():add("Lua-Scripts-Enabled", "Processed")
      end

kubectl apply -f ambassador-module.yaml
module.getambassador.io/ambassador created

kubectl get module
NAME         AGE
ambassador   53s

可以看到增加了一個響應頭"lua-scripts-enabled: Processed"。

curl -i http://192.168.1.50:38080
HTTP/1.1 200 OK
date: Sat, 07 Dec 2019 02:52:59 GMT
content-type: text/plain
server: envoy
x-envoy-upstream-service-time: 7
lua-scripts-enabled: Processed
transfer-encoding: chunked


Hostname: echo-5599595fd9-ffxpn

Pod Information:
        node name:      k8s-node2
        pod name:       echo-5599595fd9-ffxpn
        pod namespace:  default
        pod IP: 10.244.2.4

Server values:
        server_version=nginx: 1.14.2 - lua: 10015

Request Information:
        client_address=10.244.1.5
        method=GET
        real path=/
        query=
        request_version=1.1
        request_scheme=http
        request_uri=http://192.168.1.50:8080/

Request Headers:
        accept=*/*
        content-length=0
        host=192.168.1.50:38080
        user-agent=curl/7.29.0
        x-envoy-expected-rq-timeout-ms=3000
        x-envoy-internal=true
        x-envoy-original-path=/
        x-forwarded-for=10.244.0.0
        x-forwarded-proto=http
        x-request-id=c294858d-bdfe-4c66-b5e0-ad48db281dfe

Request Body:
        -no body in request-