深入浅出Istio 流量管理2 来源服务路由和url重定向

概述

本文概述了Istio中流量管理的来源服务路由和url重定向。

根据来源服务进行路由

来自不同版本的服务访问不同版本的目标服务，v1版本的 sleep flaskapp 发出的请求由flaskapp v1版本提供响应，其他版本由flaskapp v2版本负责。

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: flaskapp
spec:
  hosts:
    - flaskapp
  http:
    - match:
        - sourceLabels:
            app: sleep
            version: v1
      route:
        - destination:
            host: flaskapp
            subset: v1
    - route:
        - destination:
            host: flaskapp
            subset: v2

进入容器测试：oc rsh sleep-v1-56f9b9db86-lc6xp

for i in `seq 10`;do http --body http://flaskapp/env/version;done
v1
v1
v1
v1
v1
v1
v1
v1
v1
v1

进入容器测试：oc rsh sleep-v2-d596c4dc6-6hv7j

for i in `seq 10`;do http --body http://flaskapp/env/version;done
v2
v2
v2
v2
v2
v2
v2
v2
v2
v2

URI 重定向

还有另外一种对目标路由的分流方式，即根据 URL 进行重定向：
sleep服务发起对flaskapp服务/env/HOSTNAME路径的请求

• 如果请求来自版本v2，那么将其照实返回
• 如果请求来自版本v1，那么将其请求路径由/env/HOSTNAME修改为/env/version

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: flaskapp
spec:
  hosts:
    - flaskapp
  http:
    - match:
        - sourceLabels:
            app: sleep
            version: v1
          uri:
            exact: "/env/HOSTNAME"
      redirect:
        uri: /env/version
    - route:
        - destination:
            host: flaskapp
            subset: v2

v1测试结果：oc rsh sleep-v1-56f9b9db86-lc6xp

env|grep HOSTNAME
HOSTNAME=sleep-v1-56f9b9db86-lc6xp

# http http://flaskapp/env/HOSTNAME
HTTP/1.1 301 Moved Permanently
content-length: 0
date: Tue, 16 Jun 2020 02:32:03 GMT
location: http://flaskapp/env/version
server: envoy

发现返回了301指令，在命令中加入跟随重定向的指令：

# http --follow http://flaskapp/env/HOSTNAME
HTTP/1.1 200 OK
content-length: 2
content-type: text/html; charset=utf-8
date: Tue, 16 Jun 2020 02:36:48 GMT
server: envoy
x-envoy-upstream-service-time: 4

v2

v2测试结果：oc rsh sleep-v2-d596c4dc6-6hv7j

# http http://flaskapp/env/HOSTNAME
HTTP/1.1 200 OK
content-length: 28
content-type: text/html; charset=utf-8
date: Tue, 16 Jun 2020 03:15:21 GMT
server: envoy
x-envoy-upstream-service-time: 6

flaskapp-v2-7d7f85c4bd-27vml

redirect 令会把URI进行整体替换，因此灵活性不高；另外301无法支持
Post方法。以下是httpbin设置一个使用Post 方法的重定向：

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: httpbin
spec:
  hosts:
    - httpbin
  http:
    - match:
        - uri:
            exact: "/get"
      redirect:
        uri: /post
    - route:
        - destination:
            host: httpbin

测试结果：

# http -f POST http://httpbin:8000/post data=nothing
HTTP/1.1 200 OK
access-control-allow-credentials: true
access-control-allow-origin: *
content-length: 586
content-type: application/json
date: Tue, 16 Jun 2020 07:25:51 GMT
server: envoy
x-envoy-upstream-service-time: 11

{
    "args": {},
    "data": "",
    "files": {},
    "form": {
        "data": "nothing"
    },
    "headers": {
        "Accept": "*/*",
        "Accept-Encoding": "gzip, deflate",
        "Content-Length": "12",
        "Content-Type": "application/x-www-form-urlencoded; charset=utf-8",
        "Host": "httpbin:8000",
        "User-Agent": "HTTPie/2.1.0",
        "X-B3-Parentspanid": "2813ee1b795f16c1",
        "X-B3-Sampled": "0",
        "X-B3-Spanid": "1787038c7b48edf1",
        "X-B3-Traceid": "a0bbfba3e48bb8162813ee1b795f16c1"
    },
    "json": null,
    "origin": "127.0.0.1",
    "url": "http://httpbin:8000/post"
}

rewrite 方法和 redirect 方法的不同之处在于，在 rewrite 方法的 match 一节必须
含对目标的定义。并且， rewrite 方法不能和 redirect 方法共存。

参考

深入浅出Istio：Service Mesh快速入门与实践