Eureka源碼解析服務(wù)離線狀態(tài)變更
環(huán)境
- eureka版本:1.10.11
- Spring Cloud : 2020.0.2
- Spring Boot :2.4.4
測試代碼:github.com/hsfxuebao/s…
1. 服務(wù)離線的方式
服務(wù)離線,即某服務(wù)不能對外提供服務(wù)了。服務(wù)離線的原因有兩種:服務(wù)下架與服務(wù)下線。
- 服務(wù)下架:表示這個已經(jīng)被kill掉了,不能對外提供服務(wù),自己也不能訪問
- 服務(wù)下線:只是該服務(wù)不能被 eureka server端發(fā)現(xiàn)(不能注冊),不能被遠程訪問,但是可以自己訪問自己的服務(wù)
1.1 基于Actuator監(jiān)控器實現(xiàn)
提交如下POST請求
,可實現(xiàn)相應(yīng)的服務(wù)離線操作:
- 服務(wù)下架:http://localhost:端口號/actuator/shutdown 無需請求體
- 服務(wù)下線:http://localhost:端口號/actuator/serviceregistry 請求體為(該方法稱為服務(wù)平滑上下 線)
{ "status":"OUT_OF_SERVICE" 或 "UP" }
注意,從Spring Cloud 2020.0.0版本開始,服務(wù)平滑上下線的監(jiān)控終端由service-registry變更為 了serviceregistry
1.2 直接向Eureka Server提交請求
可以通過直接向Eureka Server
提交不同的請求的方式來實現(xiàn)指定服務(wù)離線操作:
服務(wù)下架:通過向eureka server
發(fā)送DELETE請求
來刪除指定client
的服務(wù)
http://${server}:${port}/eureka/apps/${serviceName}/${instanceId}
服務(wù)下線:通過向eureka server
發(fā)送PUT請求
來修改指定client的status
,其中${value}
的取值 為:OUT_OF_SERVICE或UP
http://${server}:${port}/eureka/apps/${serviceName}/${instanceId}/stat us?value=${value}
1.3 特殊狀態(tài)CANCEL_OVERRIDE
用戶提交的狀態(tài)修改請求中指定的狀態(tài),除了InstanceInfo
的內(nèi)置枚舉類InstanceStatus
中定義的狀態(tài) 外,還可以是CANCEL_OVERRIDE狀態(tài)
。
若用戶提交的狀態(tài)為CANCEL_OVERRIDE
,則Client會通過Jersey
向Server提交一個DELETE請求
,用于 在Server端將對應(yīng)InstanceInfo
的overridenStatus
修改為UNKNWON
,即刪除了原來的overridenStatus
的狀態(tài)值。此時,該Client發(fā)送的心跳Server是不接收的。Server會向該Client返回404
。
2. 服務(wù)下架源碼
public class EurekaClientAutoConfiguration { @Configuration(proxyBeanMethods = false) @ConditionalOnRefreshScope protected static class RefreshableEurekaClientConfiguration { @Bean(destroyMethod = "shutdown") @ConditionalOnMissingBean(value = EurekaClient.class, search = SearchStrategy.CURRENT) @org.springframework.cloud.context.config.annotation.RefreshScope @Lazy public EurekaClient eurekaClient(ApplicationInfoManager manager, EurekaClientConfig config, EurekaInstanceConfig instance, @Autowired(required = false) HealthCheckHandler healthCheckHandler) { } } }
當(dāng)Actuator
監(jiān)聽到服務(wù)下架時,會調(diào)用DiscoveryClient.shutdown()
方法:
// 服務(wù)下架 @PreDestroy @Override public synchronized void shutdown() { if (isShutdown.compareAndSet(false, true)) { logger.info("Shutting down DiscoveryClient ..."); // 注銷狀態(tài)改變監(jiān)聽器 if (statusChangeListener != null && applicationInfoManager != null) { applicationInfoManager.unregisterStatusChangeListener(statusChangeListener.getId()); } // todo 取消定時任務(wù) cancelScheduledTasks(); // If APPINFO was registered if (applicationInfoManager != null && clientConfig.shouldRegisterWithEureka() && clientConfig.shouldUnregisterOnShutdown()) { applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN); // todo 服務(wù)下架 unregister(); } if (eurekaTransport != null) { eurekaTransport.shutdown(); } heartbeatStalenessMonitor.shutdown(); registryStalenessMonitor.shutdown(); Monitors.unregisterObject(this); logger.info("Completed shut down of DiscoveryClient"); } }
有兩個核心方法,我們分別看一下。
2.1 cancelScheduledTasks()
取消定時任務(wù)。
private void cancelScheduledTasks() { if (instanceInfoReplicator != null) { instanceInfoReplicator.stop(); } if (heartbeatExecutor != null) { heartbeatExecutor.shutdownNow(); } if (cacheRefreshExecutor != null) { cacheRefreshExecutor.shutdownNow(); } if (scheduler != null) { scheduler.shutdownNow(); } if (cacheRefreshTask != null) { cacheRefreshTask.cancel(); } if (heartbeatTask != null) { heartbeatTask.cancel(); } }
2.2 unregister()
發(fā)送服務(wù)下架請求。
void unregister() { // It can be null if shouldRegisterWithEureka == false if(eurekaTransport != null && eurekaTransport.registrationClient != null) { try { logger.info("Unregistering ..."); EurekaHttpResponse<Void> httpResponse = eurekaTransport.registrationClient.cancel(instanceInfo.getAppName(), instanceInfo.getId()); logger.info(PREFIX + "{} - deregister status: {}", appPathIdentifier, httpResponse.getStatusCode()); } catch (Exception e) { logger.error(PREFIX + "{} - de-registration failed{}", appPathIdentifier, e.getMessage(), e); } } }
@Override public EurekaHttpResponse<Void> cancel(String appName, String id) { String urlPath = "apps/" + appName + '/' + id; ClientResponse response = null; try { Builder resourceBuilder = jerseyClient.resource(serviceUrl).path(urlPath).getRequestBuilder(); addExtraHeaders(resourceBuilder); // delete 請求 response = resourceBuilder.delete(ClientResponse.class); return anEurekaHttpResponse(response.getStatus()).headers(headersOf(response)).build(); } finally { if (logger.isDebugEnabled()) { logger.debug("Jersey HTTP DELETE {}/{}; statusCode={}", serviceUrl, urlPath, response == null ? "N/A" : response.getStatus()); } if (response != null) { response.close(); } } }
服務(wù)下架請求:DELETE請求,path:"apps/" + appName + '/' + id;
3. 服務(wù)下線源碼分析(狀態(tài)變更)
Eureka 整合了 Actuator
,可以通過 Actuator
變更實例在服務(wù)端的狀態(tài)。spring cloud整合eureka,入口在 spring-cloud-common
下的spring.factories
:
@Configuration(proxyBeanMethods = false) public class ServiceRegistryAutoConfiguration { @ConditionalOnBean(ServiceRegistry.class) @ConditionalOnClass(Endpoint.class) protected class ServiceRegistryEndpointConfiguration { @Autowired(required = false) private Registration registration; @Bean @ConditionalOnAvailableEndpoint public ServiceRegistryEndpoint serviceRegistryEndpoint(ServiceRegistry serviceRegistry) { ServiceRegistryEndpoint endpoint = new ServiceRegistryEndpoint(serviceRegistry); endpoint.setRegistration(this.registration); return endpoint; } } }
ServiceRegistryAutoConfiguration
是一個配置類,往容器中注入ServiceRegistryEndpoint
:
@Endpoint(id = "serviceregistry") public class ServiceRegistryEndpoint { ... @WriteOperation public ResponseEntity<?> setStatus(String status) { Assert.notNull(status, "status may not by null"); if (this.registration == null) { return ResponseEntity.status(HttpStatus.NOT_FOUND).body("no registration found"); } // 變更狀態(tài) this.serviceRegistry.setStatus(this.registration, status); return ResponseEntity.ok().build(); } @ReadOperation public ResponseEntity getStatus() { if (this.registration == null) { return ResponseEntity.status(HttpStatus.NOT_FOUND).body("no registration found"); } // 獲取狀態(tài) return ResponseEntity.ok().body(this.serviceRegistry.getStatus(this.registration)); } }
3.1 變更狀態(tài)
核心方法ServiceRegistry#setStatus
:
@Override public void setStatus(EurekaRegistration registration, String status) { // 獲取實例信息 InstanceInfo info = registration.getApplicationInfoManager().getInfo(); // TODO: howto deal with delete properly? if ("CANCEL_OVERRIDE".equalsIgnoreCase(status)) { // 如果變更狀態(tài)請求傳過來 status = "CANCEL_OVERRIDE",向服務(wù)端發(fā)起 Jersey 刪除狀態(tài)請求 registration.getEurekaClient().cancelOverrideStatus(info); return; } // TODO: howto deal with status types across discovery systems? InstanceInfo.InstanceStatus newStatus = InstanceInfo.InstanceStatus.toEnum(status); // 如果不是刪除狀態(tài),則向服務(wù)端發(fā)起 Jersey 變更狀態(tài)請求 registration.getEurekaClient().setStatus(newStatus, info); }
核心流程有2個,分別為
status
為CANCEL_OVERRIDE
:
public void cancelOverrideStatus(InstanceInfo info) { getEurekaHttpClient().deleteStatusOverride(info.getAppName(), info.getId(), info); } @Override public EurekaHttpResponse<Void> deleteStatusOverride(String appName, String id, InstanceInfo info) { String urlPath = "apps/" + appName + '/' + id + "/status"; ClientResponse response = null; try { Builder requestBuilder = jerseyClient.resource(serviceUrl) .path(urlPath) .queryParam("lastDirtyTimestamp", info.getLastDirtyTimestamp().toString()) .getRequestBuilder(); addExtraHeaders(requestBuilder); // DELETE 請求 response = requestBuilder.delete(ClientResponse.class); return anEurekaHttpResponse(response.getStatus()).headers(headersOf(response)).build(); } finally { if (logger.isDebugEnabled()) { logger.debug("Jersey HTTP DELETE {}/{}; statusCode={}", serviceUrl, urlPath, response == null ? "N/A" : response.getStatus()); } if (response != null) { response.close(); } } }
刪除deleteStatusOverride請求: DELETE請求 path:"apps/" + appName + '/' + id + "/status"
直接調(diào)用setStatus()
方法:
@Override public EurekaHttpResponse<Void> statusUpdate(String appName, String id, InstanceStatus newStatus, InstanceInfo info) { String urlPath = "apps/" + appName + '/' + id + "/status"; ClientResponse response = null; try { Builder requestBuilder = jerseyClient.resource(serviceUrl) .path(urlPath) .queryParam("value", newStatus.name()) .queryParam("lastDirtyTimestamp", info.getLastDirtyTimestamp().toString()) .getRequestBuilder(); addExtraHeaders(requestBuilder); // PUT 請求 response = requestBuilder.put(ClientResponse.class); return anEurekaHttpResponse(response.getStatus()).headers(headersOf(response)).build(); } finally { if (logger.isDebugEnabled()) { logger.debug("Jersey HTTP PUT {}/{}; statusCode={}", serviceUrl, urlPath, response == null ? "N/A" : response.getStatus()); } if (response != null) { response.close(); } } }
變更狀態(tài)請求:PUT請求,path為 :"apps/" + appName + '/' + id + "/status"
3.2 獲取狀態(tài)
// EurekaServiceRegistry.class public Object getStatus(EurekaRegistration registration) { String appname = registration.getApplicationInfoManager().getInfo().getAppName(); String instanceId = registration.getApplicationInfoManager().getInfo().getId(); // 獲取本地實例信息 InstanceInfo info = registration.getEurekaClient().getInstanceInfo(appname, instanceId); HashMap<String, Object> status = new HashMap<>(); if (info != null) { // 從實例信息取出相應(yīng)狀態(tài)返回 status.put("status", info.getStatus().toString()); status.put("overriddenStatus", info.getOverriddenStatus().toString()); } else { // 如果實例信息不存在,則返回 UNKNOWN 狀態(tài) status.put("status", UNKNOWN.toString()); } return status; }
參考文章
springcloud-source-study學(xué)習(xí)github地址
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