Envoy：离群点检测 outlier detection

2023-07-22 16:08:16

outlier detection

在异常检测领域中，常常需要决定新观察的点是否属于与现有观察点相同的分布（则它称为inlier），或者被认为是不同的（称为outlier）。离群是异常的数据，但是不一定是错误的数据点。

在Envoy中，离群点检测是动态确定上游集群中是否有某些主机表现不正常，然后将它们从正常的负载均衡集群中删除的过程。outlier detection可以与healthy check同时/独立启用，并构成整个上游运行状况检查解决方案的基础。

此处概念不做过多的说明，具体可以参考官方文档与自行google

监测类型

连续的5xx
连续的网关错误
连续的本地来源错误

更多介绍参考官方文档 outlier detection

离群检测测试

说明，此处只能在单机环境测试更多还的参考与实际环境

环境准备

docker-compose 模拟后端5个节点

version: '3'

services:

  envoy:

    image: envoyproxy/envoy-alpine:v1.15-latest

    environment:

    - ENVOY_UID=0

    ports:

    - 80:80

    - 443:443

    - 82:9901

    volumes:

    - ./envoy.yaml:/etc/envoy/envoy.yaml

    networks:

      envoymesh:

        aliases:

        - envoy

    depends_on:

    - webserver1

    - webserver2

  webserver1:

    image: sealloong/envoy-end:latest

    networks:

      envoymesh:

        aliases:

        - myservice

        - webservice

    expose:

    - 90

  webserver2:

    image: sealloong/envoy-end:latest

    networks:

      envoymesh:

        aliases:

        - myservice

        - webservice

    expose:

    - 90

  webserver3:

    image: sealloong/envoy-end:latest

    networks:

      envoymesh:

        aliases:

        - myservice

        - webservice

    expose:

    - 90

  webserver4:

    image: sealloong/envoy-end:latest

    networks:

      envoymesh:

        aliases:

        - myservice

        - webservice

    expose:

    - 90

  webserver5:

    image: sealloong/envoy-end:latest

    networks:

      envoymesh:

        aliases:

        - myservice

        - webservice

    expose:

    - 90

networks:

  envoymesh: {}

envoy 配置文件

admin:

  access_log_path: /dev/null

  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_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_service }

          http_filters:

          - name: envoy.filters.http.router

  clusters:

  - name: local_service

    connect_timeout: 0.25s

    type: STRICT_DNS

    lb_policy: ROUND_ROBIN

    load_assignment:

      cluster_name: local_service

      endpoints:

      - lb_endpoints:

        - endpoint:

            address:

              socket_address: { address: webservice, port_value: 90 }

    health_checks:

      timeout: 3s

      interval: 90s

      unhealthy_threshold: 5

      healthy_threshold: 5

      no_traffic_interval: 240s

      http_health_check:

        path: "/ping"

        expected_statuses:

          start: 200

          end: 201

    outlier_detection:

      consecutive_5xx: 2

      base_ejection_time: 30s

      max_ejection_percent: 40

      interval: 20s

      success_rate_minimum_hosts: 5

      success_rate_request_volume: 10

配置说明

    outlier_detection:

      consecutive_5xx: 2 # 连续的5xx错误数量

      base_ejection_time: 30s # 弹出主机的基准时间。实际时间等于基本时间乘以主机弹出的次数

      max_ejection_percent: 40 # 可弹出主机集群的最大比例，默认值为10% ，此处为40% 即集群中5个节点的2个节点

      interval: 20s # 间隔时间

      success_rate_minimum_hosts: 5 # 集群中最小主机数量

      success_rate_request_volume: 10 # 在一个时间间隔内中收集请求检测的最小数量

此处为了效果，将主动检测状态时间增加，主机弹出时间增加

路由

/502bad 模拟一个502的错误

运行结果

模拟一些5xx请求和200请求

 workers

envoy_1       | [2020-09-13 06:10:01.093][1][warning][main] [source/server/server.cc:537] there is no configured limit to the number of allowed active connections. Set a limit via the runtime key overload.global_downstream_max_connections

webserver2_1  | [GIN] 2020/09/13 - 06:10:08 | 200 |      63.272?s |      172.22.0.7 | GET      "/"

webserver5_1  | [GIN] 2020/09/13 - 06:10:10 | 200 |      46.732?s |      172.22.0.7 | GET      "/"

webserver1_1  | [GIN] 2020/09/13 - 06:10:11 | 200 |       45.43?s |      172.22.0.7 | GET      "/"

webserver3_1  | [GIN] 2020/09/13 - 06:10:13 | 502 |      43.858?s |      172.22.0.7 | GET      "/502bad"

webserver4_1  | [GIN] 2020/09/13 - 06:10:14 | 502 |      47.486?s |      172.22.0.7 | GET      "/502bad"

webserver2_1  | [GIN] 2020/09/13 - 06:10:15 | 200 |      15.691?s |      172.22.0.7 | GET      "/"

webserver5_1  | [GIN] 2020/09/13 - 06:10:16 | 200 |      14.719?s |      172.22.0.7 | GET      "/"

webserver1_1  | [GIN] 2020/09/13 - 06:10:16 | 200 |      15.758?s |      172.22.0.7 | GET      "/"

webserver3_1  | [GIN] 2020/09/13 - 06:10:17 | 502 |      15.697?s |      172.22.0.7 | GET      "/502bad"

webserver2_1  | [GIN] 2020/09/13 - 06:10:17 | 502 |      14.002?s |      172.22.0.7 | GET      "/502bad"

webserver5_1  | [GIN] 2020/09/13 - 06:10:17 | 502 |      14.913?s |      172.22.0.7 | GET      "/502bad"

webserver1_1  | [GIN] 2020/09/13 - 06:10:18 | 502 |      14.911?s |      172.22.0.7 | GET      "/502bad"

webserver4_1  | [GIN] 2020/09/13 - 06:10:18 | 502 |      30.429?s |      172.22.0.7 | GET      "/502bad"

webserver5_1  | [GIN] 2020/09/13 - 06:10:19 | 200 |      14.377?s |      172.22.0.7 | GET      "/"

webserver1_1  | [GIN] 2020/09/13 - 06:10:19 | 200 |      14.861?s |      172.22.0.7 | GET      "/"

webserver2_1  | [GIN] 2020/09/13 - 06:10:19 | 200 |      18.924?s |      172.22.0.7 | GET      "/"

webserver5_1  | [GIN] 2020/09/13 - 06:10:19 | 200 |      15.899?s |      172.22.0.7 | GET      "/"

webserver1_1  | [GIN] 2020/09/13 - 06:10:19 | 200 |      24.849?s |      172.22.0.7 | GET      "/"