Eureka usage record

Knowledge point 1, Self-protection model

Protection mode is mainly in a group of clients and Eureka Server Use when there are network partition scenarios between . Once in protected mode ,Eureka Server Will try to protect information in the registry of its services , Data in the service registry is no longer deleted . When the network is recovered , The Eureka Server The node automatically exits protected mode .

eureka.server.enableSelfPreservation=false

Knowledge point 2,Eureka Application example ID The name of the format

When the client registers , Service Instance ID The format of the default value for is as follows （ Host name ： The service name ： Service port ）：

${
    spring.cloud.client.hostname}:${
    spring.application.name}:${
    spring.application. instance_id:${
    server.port}}

If you need to customize the format ： The service name ： Where the service is IP： Service port

eureka.instance.instance-id=${
    spring.application.name}:${
    spring.cloud.client.ip-address}:${
    server.port}

At this time, the above link is still the hostname , Increase the configuration , Show as ip

eureka.instance.preferIpAddress=true

Custom jump link

eureka.instance.status-page-url-path=/hello

Knowledge point 3,Eureka Quickly remove failed services during development

In the actual development process , We might be able to restart the service all the time , because Eureka It has its own protection mechanism , Therefore, after the node is offline , Service information will always exist in Eureka in . We can make the removal faster by adding some configurations , Only in the development environment, of course , It is not recommended in production environment .

First of all in our eureka-server Two new configurations are added in , Turn off self-protection and clean-up interval ：

eureka.server.enable-self-preservation=false
#  Default  60000  millisecond 
eureka.server.eviction-interval-timer-in-ms=5000

Then configure the following content in the specific client service ：

eureka.client.healthcheck.enabled=true
#  Default  30  second 
eureka.instance.lease-renewal-interval-in-seconds=5
#  Default  90  second 
eureka.instance.lease-expiration-duration-in-seconds=5

eureka.client.healthcheck.enabled It's used to turn on the health check , Need to be in pom.xml Introduction in actuator Dependence , The code is as follows .

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

among ：

• eureka.instance.lease-renewal-interval-in-seconds Express Eureka Client Send a heartbeat to server The frequency of the end .
• eureka.instance.lease-expiration-duration-in-seconds Express Eureka Server Last received client After my heart beat , Timeout waiting for next heartbeat , If you don't receive the next heartbeat in this time , Then remove the Instance.

added Instance For configuration information, please refer to the configuration class in the source code ：org.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean.

added Server For configuration information, please refer to the configuration class in the source code ：org.springframework.cloud.netflix.eureka.server.EurekaServerConfigBean.

Knowledge point 4,EurekaClient Use

There are two ways

• com.netflix.discovery.EurekaClient

	@GetMapping("/test")
	public Object serviceUrl() {
    
		return eurekaClient.getInstancesByVipAddress("eureka-provider-app", false);
	}

• Spring Cloud Reseal ,org.springframework.cloud.client.discovery.DiscoveryClient

	@GetMapping("/test2")
	public Object serviceUrl2() {
    
	    return discoveryClient.getInstances("eureka-provider-app");
	}