Eureka
create by nohi 20220718
参考：
- 深入Eureka Server启动源码分析：https://www.jianshu.com/p/f720d3857830
- 默认配置：https://www.cnblogs.com/liukaifeng/p/10052594.html
Eureka Server：
spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfigurationEurekaServerAutoConfiguration
DefaultEurekaServerContext
EurekaServerInitializerConfiguration
server初始化 start()
EurekaServerBootstrap.contextInitialized -> initEurekaServerContext
initEurekaEnvironment(); initEurekaServerContext(); context.setAttribute(EurekaServerContext.class.getName(), this.serverContext);EurekaServerBootstrap.initEurekaServerContext
int registryCount = this.registry.syncUp(); // 同步其他结点 this.registry.openForTraffic(this.applicationInfoManager, registryCount);openForTraffic -〉 PeerAwareInstanceRegistryImpl.openForTraffic ->
super.postInit();AbstractInstanceRegistry.postInit -> EvictionTask
renewsLastMin.start(); if (evictionTaskRef.get() != null) { evictionTaskRef.get().cancel(); } evictionTaskRef.set(new EvictionTask()); evictionTimer.schedule(evictionTaskRef.get(), serverConfig.getEvictionIntervalTimerInMs(), serverConfig.getEvictionIntervalTimerInMs());
InstanceRegistry- cancel
- register
定时器：`DefaultEurekaServerContext.initialize()
registry.init(peerEurekaNodes); -> PeerAwareInstanceRegistryImpl.init
initializedResponseCache(); scheduleRenewalThresholdUpdateTask(); initRemoteRegionRegistry();scheduleRenewalThresholdUpdateTask
timer.schedule(new TimerTask() { @Override public void run() { updateRenewalThreshold(); } }, serverConfig.getRenewalThresholdUpdateIntervalMs(), serverConfig.getRenewalThresholdUpdateIntervalMs());
restFull
apps:
http://127.0.0.1:7001/eureka/appsinstance:
http://127.0.0.1:7001/eureka/apps/SYS-USER
服务
com.netflix.eureka.resources.ApplicationResource- 注册
addInstance
- 注册
com.netflix.eureka.resources.InstanceResource- 更新: renewLease
- 删除: cancelLease
Eureka Client
源码
初始化：com.netflix.discovery.DiscoveryClient.DiscoveryClient
- @Inject方式初调用
- 调用 initScheduledTasks() 初始化缓存、心跳任务
com.netflix.discovery.DiscoveryClient.initScheduledTasks
- cacheRefreshTask 缓存
- heartbeatTask 心跳
- statusChangeListener 状态变更
1.首先调用接口为什么会直接发送请求？ 原因就是Spring扫描了@FeignClient注解，并且根据配置的信息生成代理类，调用的接口实际上调用的是生成的代理类。 2 其次请求是如何被Feign接管的？ Feign通过扫描@EnableFeignClients注解中配置包路径，扫描@FeignClient注解并将注解配置的信息注入到Spring容器中，类型为FeignClientFactoryBean； 然后通过FeignClientFactoryBean的getObject()方法得到不同动态代理的类并为每个方法创建一个SynchronousMethodHandler对象； 为每一个方法创建一个动态代理对象， 动态代理的实现是 ReflectiveFeign.FeignInvocationHanlder，代理被调用的时候，会根据当前调用的方法，转到对应的 SynchronousMethodHandler。 这样我们发出的请求就能够被已经配置好各种参数的Feign handler进行处理，从而被Feign托管。 3 请求如何被Feign分发的？ 上一个问题已经回答了Feign将每个方法都封装成为代理对象，那么当该方法被调用时，真正执行逻辑的是封装好的代理对象进行处理，执行对应的服务调用逻辑。SynchronousMethodHandler.invoke-> executeAndDecode -> client(FeignBlockingLoadBalancerClient).execute- FeignBlockingLoadBalancerClient.execute -> loadBalancerClient(BlockingLoadBalancerClient).choose -> loadBalancer(RoundRobinLoadBalancer).choose(request)
load balance
- Spring Cloud LoadBalancer知乎
- 默认：RoundRobinLoadBalancer
配置
- eureka.instance.lease-renewal-interval-in-seconds 该服务实例向注册中心发送心跳间隔 30s
- eureka.client.registry-fetch-interval-seconds 指示从eureka服务器获取注册表信息的频率（s） 30
注册/更新/删除
服务类：
com.netflix.discovery.DiscoveryClient通讯类
org.springframework.cloud.netflix.eureka.http.RestTemplateEurekaHttpClient注册：
registerorg.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration.EurekaAutoServiceRegistration
注册：`register`
post http://127.0.0.1:7001/eureka/apps/SYS-USER{ "instance": { "instanceId": "10.0.0.53:8001", "app": "SYS-USER", "appGroupName": null, "ipAddr": "10.0.0.53", "sid": "na", "homePageUrl": "http://10.0.0.53:8001/", "statusPageUrl": "http://10.0.0.53:8001/actuator/info", "healthCheckUrl": "http://10.0.0.53:8001/actuator/health", "secureHealthCheckUrl": null, "vipAddress": "sys-user", "secureVipAddress": "sys-user", "countryId": 1, "dataCenterInfo": { "@class": "com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo", "name": "MyOwn" }, "hostName": "10.0.0.53", "status": "UP", "overriddenStatus": "UNKNOWN", "leaseInfo": { "renewalIntervalInSecs": 30, "durationInSecs": 90, "registrationTimestamp": 0, "lastRenewalTimestamp": 0, "evictionTimestamp": 0, "serviceUpTimestamp": 0 }, "isCoordinatingDiscoveryServer": false, "lastUpdatedTimestamp": 1658238666529, "lastDirtyTimestamp": 1658238667158, "actionType": null, "asgName": null, "port": { "$": 8001, "@enabled": "true" }, "securePort": { "$": 443, "@enabled": "false" }, "metadata": { "management.port": "8001" } } }
更新：
DiscoveryClient -> renew(HeartbeatThread)curl -X PUT http://10.0.0.210:7001/eureka/apps/SYS-USER/10.0.0.53:8001?status=UP&lastDirtyTimestamp=1658240856334删除：
DiscoveryClient.shutdown- RestTemplateEurekaHttpClient.cancel
curl -X delete http://10.0.0.210:7001/eureka/apps/SYS-USER/10.0.0.210:8801
应用/实例列表获取
- 应用列表：http://10.0.0.210:7001/eureka/apps
- 实例列表：http://10.0.0.210:7001/eureka/apps/SYS-USERS
自我保护机制
CAP（Consistency 一致性 Availability 可用性 Partition tolerance 分区容错性）
Eureka: AP
Eureka-Server和client端的通信被终止,Eureka宁可保留也许已经宕机了的client端 ， 也不愿意将可以用的client端一起剔除
关闭自我保护机制
eureka: server: enable-self-preservation: false #（设为false，关闭自我保护主要）- 定期清理：`AbstractInstanceRegistry.evict()
重要变量
# InstanceR egistryProperties.expectedNumberOfClientsSendingRenews this.expectedNumberOfRenewsPerMin = count * 2; this.numberOfRenewsPerMinThreshold =(int) (this.expectedNumberOfRenewsPerMin * serverConfig.getRenewalPercentThreshold()); # EurekaServerConfigBean.renewalPercentThreshold serverConfig.getRenewalPercentThreshold() 20220727 eureka3.1.1 已变更 synchronized (lock) { if (this.expectedNumberOfClientsSendingRenews > 0) { // Since the client wants to cancel it, reduce the number of clients to send renews. this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews - 1; updateRenewsPerMinThreshold(); } }- expectedNumberOfRenewsPerMin ：每分钟最大的续约数量. 客户端数量 * 2 - numberOfRenewsPerMinThreshold ： 每分钟最小续约数量= expectedNumberOfRenewsPerMin * 最低百分比（默认值为0.85）- 更新场景
- Eureka-Server初始化，cancle主动下线， 客户端注册 ,定时器
- 更新场景