Envoy熔断

### 环境说明
五个Service:
- envoy：Front Proxy,地址为172.31.35.2
- webserver01：第一个后端服务
- webserver01-sidecar：第一个后端服务的Sidecar Proxy,地址为172.31.35.11, 别名为red和webservice1
- webserver02：第二个后端服务
- webserver02-sidecar：第一个后端服务的Sidecar Proxy,地址为172.31.35.12, 别名为blue和webservice1
- webserver03：第三个后端服务
- webserver03-sidecar：第一个后端服务的Sidecar Proxy,地址为172.31.35.13, 别名为green和webservice1
- webserver04：第四个后端服务
- webserver04-sidecar：第四个后端服务的Sidecar Proxy,地址为172.31.35.14, 别名为gray和webservice2
- webserver05：第五个后端服务
- webserver05-sidecar：第五个后端服务的Sidecar Proxy,地址为172.31.35.15, 别名为black和webservice2

启动

docker-compose up

[root@k8s-master circuit-breaker]# cat docker-compose.yaml 
version: '3'

services:
  front-envoy:
    #image: envoyproxy/envoy-alpine:v1.21-latest
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
      - ./front-envoy.yaml:/etc/envoy/envoy.yaml
    networks:
      - envoymesh
    expose:
      # Expose ports 80 (for general traffic) and 9901 (for the admin server)
      - "80"
      - "9901"

  webserver01-sidecar:
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
    - ./envoy-sidecar-proxy.yaml:/etc/envoy/envoy.yaml
    hostname: red
    networks:
      envoymesh:
        ipv4_address: 172.31.35.11
        aliases:
        - webservice1
        - red

  webserver01:
    image: ikubernetes/demoapp:v1.0
    environment:
      - PORT=8080
      - HOST=127.0.0.1
    network_mode: "service:webserver01-sidecar"
    depends_on:
    - webserver01-sidecar

  webserver02-sidecar:
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
    - ./envoy-sidecar-proxy.yaml:/etc/envoy/envoy.yaml
    hostname: blue
    networks:
      envoymesh:
        ipv4_address: 172.31.35.12
        aliases:
        - webservice1
        - blue

  webserver02:
    image: ikubernetes/demoapp:v1.0
    environment:
      - PORT=8080
      - HOST=127.0.0.1
    network_mode: "service:webserver02-sidecar"
    depends_on:
    - webserver02-sidecar

  webserver03-sidecar:
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
    - ./envoy-sidecar-proxy.yaml:/etc/envoy/envoy.yaml
    hostname: green
    networks:
      envoymesh:
        ipv4_address: 172.31.35.13
        aliases:
        - webservice1
        - green

  webserver03:
    image: ikubernetes/demoapp:v1.0
    environment:
      - PORT=8080
      - HOST=127.0.0.1
    network_mode: "service:webserver03-sidecar"
    depends_on:
    - webserver03-sidecar

  webserver04-sidecar:
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
    - ./envoy-sidecar-proxy.yaml:/etc/envoy/envoy.yaml
    hostname: gray
    networks:
      envoymesh:
        ipv4_address: 172.31.35.14
        aliases:
        - webservice2
        - gray

  webserver04:
    image: ikubernetes/demoapp:v1.0
    environment:
      - PORT=8080
      - HOST=127.0.0.1
    network_mode: "service:webserver04-sidecar"
    depends_on:
    - webserver04-sidecar

  webserver05-sidecar:
    image: envoyproxy/envoy:v1.23-latest
    environment:
      - ENVOY_UID=0
      - ENVOY_GID=0
    volumes:
    - ./envoy-sidecar-proxy.yaml:/etc/envoy/envoy.yaml
    hostname: black
    networks:
      envoymesh:
        ipv4_address: 172.31.35.15
        aliases:
        - webservice2
        - black

  webserver05:
    image: ikubernetes/demoapp:v1.0
    environment:
      - PORT=8080
      - HOST=127.0.0.1
    network_mode: "service:webserver05-sidecar"
    depends_on:
    - webserver05-sidecar

networks:
  envoymesh:
    driver: bridge
    ipam:
      config:
        - subnet: 172.31.35.0/24
[root@k8s-master circuit-breaker]# cat envoy-sidecar-proxy.yaml 
# Author: MageEdu <mage@magedu.com>
# Version: v1.0.1
# Site: www.magedu.com
#
admin:
  profile_path: /tmp/envoy.prof
  access_log_path: /tmp/admin_access.log
  address:
    socket_address:
       address: 0.0.0.0
       port_value: 9901

static_resources:
  listeners:
  - name: listener_0
    address:
      socket_address: { address: 0.0.0.0, port_value: 80 }
    filter_chains:
    - filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          stat_prefix: ingress_http
          codec_type: AUTO
          route_config:
            name: local_route
            virtual_hosts:
            - name: local_service 
              domains: ["*"]
              routes:
              - match: { prefix: "/" }
                route: { cluster: local_cluster }
          http_filters:
          - name: envoy.filters.http.router
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router

  clusters:
  - name: local_cluster
    connect_timeout: 0.25s
    type: STATIC
    lb_policy: ROUND_ROBIN
    load_assignment:
      cluster_name: local_cluster
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address: { address: 127.0.0.1, port_value: 8080 }
    circuit_breakers:
      thresholds:         
        max_connections: 1
        max_pending_requests: 1
        max_retries: 2
[root@k8s-master circuit-breaker]# cat envoy-sidecar-proxy.yaml 
# Author: MageEdu <mage@magedu.com>
# Version: v1.0.1
# Site: www.magedu.com
#
admin:
  profile_path: /tmp/envoy.prof
  access_log_path: /tmp/admin_access.log
  address:
    socket_address:
       address: 0.0.0.0
       port_value: 9901

static_resources:
  listeners:
  - name: listener_0
    address:
      socket_address: { address: 0.0.0.0, port_value: 80 }
    filter_chains:
    - filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          stat_prefix: ingress_http
          codec_type: AUTO
          route_config:
            name: local_route
            virtual_hosts:
            - name: local_service 
              domains: ["*"]
              routes:
              - match: { prefix: "/" }
                route: { cluster: local_cluster }
          http_filters:
          - name: envoy.filters.http.router
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router

  clusters:
  - name: local_cluster
    connect_timeout: 0.25s
    type: STATIC
    lb_policy: ROUND_ROBIN
    load_assignment:
      cluster_name: local_cluster
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address: { address: 127.0.0.1, port_value: 8080 }
    circuit_breakers:
      thresholds:         
        max_connections: 1
        max_pending_requests: 1
        max_retries: 2
[root@k8s-master circuit-breaker]# ls
docker-compose.yaml  envoy-sidecar-proxy.yaml  front-envoy.yaml  README.md  send-requests.sh
[root@k8s-master circuit-breaker]# cat send-requests.sh 
#!/bin/bash
#
if [ $# -ne 2 ]
then
    echo "USAGE: $0 <URL> <COUNT>"
    exit 1;
fi

URL=$1
COUNT=$2
c=1
#interval="0.2"

while [[ ${c} -le ${COUNT} ]];
do
  #echo "Sending GET request: ${URL}"
  curl -o /dev/null -w '%{http_code}\n' -s ${URL} &
  (( c++ ))
#  sleep $interval
done

wait

通过send-requests.sh脚本进行webcluster1的请求测试，可发现，有部分请求的响应码为5xx，这其实就是被熔断的处理结果；

./send-requests.sh http://172.31.35.2/ 300