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 "/"
集群已弹出 20%的节点，健康检查结果为 failed_outlier_check
请求已分配到其余三台节点
30秒后，弹出主机已回复正常
再次模拟请求
30秒后，如在时间间隔内，无新增请求，节点依旧为 failed_outlier_check，有新增请求时恢复。
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