解决用docker 微服务注册Eureka的问题

问题现象

当我们把微服务部署在docker 容器中， 注册在Eureka里的时候， 在Eureka的管理页面中见到的instance id是这样的：

instance_id：的值是 DockerId：spring.application.name: server.port

其实instance_id 的值是什么不是关键。
关键是当我们点解某个节点时， 它也是用dockerIid 当左 hostname去访问。这就出问题了'

当我们查询日志时

07-21 14:47:24:274 DEBUG 1 --- [nio-8080-exec-3] c.i.order.mapper.OrderMapper.findById    : <==      Total: 1
url:http://DEMO-CLOUD-USER-SERVICE/user/2
07-21 14:47:24:724  INFO 1 --- [nio-8080-exec-3] c.netflix.config.ChainedDynamicProperty  : Flipping property: DEMO-CLOUD-USER-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
07-21 14:47:24:790  INFO 1 --- [nio-8080-exec-3] c.n.u.concurrent.ShutdownEnabledTimer    : Shutdown hook installed for: NFLoadBalancer-PingTimer-DEMO-CLOUD-USER-SERVICE
07-21 14:47:24:791  INFO 1 --- [nio-8080-exec-3] c.netflix.loadbalancer.BaseLoadBalancer  : Client: DEMO-CLOUD-USER-SERVICE instantiated a LoadBalancer: DynamicServerListLoadBalancer:{NFLoadBalancer:name=DEMO-CLOUD-USER-SERVICE,current list of Servers=[],Load balancer stats=Zone stats: {},Server stats: []}ServerList:null
07-21 14:47:24:806  INFO 1 --- [nio-8080-exec-3] c.n.l.DynamicServerListLoadBalancer      : Using serverListUpdater PollingServerListUpdater
07-21 14:47:24:857  INFO 1 --- [nio-8080-exec-3] c.netflix.config.ChainedDynamicProperty  : Flipping property: DEMO-CLOUD-USER-SERVICE.ribbon.ActiveConnectionsLimit to use NEXT property: niws.loadbalancer.availabilityFilteringRule.activeConnectionsLimit = 2147483647
07-21 14:47:24:859  INFO 1 --- [nio-8080-exec-3] c.n.l.DynamicServerListLoadBalancer      : DynamicServerListLoadBalancer for client DEMO-CLOUD-USER-SERVICE initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=DEMO-CLOUD-USER-SERVICE,current list of Servers=[43ab279eaa63:8081,  3aab8fcfb8af:8081],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;     Instance count:2;       Active connections count: 0;    Circuit breaker tripped count: 0; Active connections per server: 0.0;]
},Server stats: [[Server:106.12.129.49:8081;    Zone:defaultZone;       Total Requests:0;       Successive connection failure:0;        Total blackout seconds:0;       Last connection made:Thu Jan 01 00:00:00 UTC 1970;      First connection made: Thu Jan 01 00:00:00 UTC 1970;       Active Connections:0;   total failure count in last (1000) msecs:0;     average resp time:0.0;  90 percentile resp time:0.0;    95 percentile resp time:0.0;    min resp time:0.0;      max resp time:0.0; stddev resp time:0.0]
, [Server:43.138.194.135:8081;  Zone:defaultZone;       Total Requests:0;       Successive connection failure:0;        Total blackout seconds:0;       Last connection made:Thu Jan 01 00:00:00 UTC 1970;      First connection made: Thu Jan 01 00:00:00 UTC 1970;       Active Connections:0;   total failure count in last (1000) msecs:0;     average resp time:0.0;  90 percentile resp time:0.0;    95 percentile resp time:0.0;    min resp time:0.0;      max resp time:0.0;stddev resp time:0.0]
]}ServerList:org.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@388efc08
07-21 14:47:24:913 ERROR 1 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://DEMO-CLOUD-USER-SERVICE/user/2": Connection refused (Connection refused); nested exception is java.net.ConnectException: Connection refused (Connection refused)] with root cause

java.net.ConnectException: Connection refused (Connection refused)
        at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_301]

见到 Eureka把 sevice demo_cloud_order_service 的 两个节点地址解释成 Servers=[43ab279eaa63:8081, 3aab8fcfb8af:8081],

导致访问失败。

解决步骤一

首先我们不能以hostname 注册Eureka， 必须用ip来注册。

在 微服务的application.yml 加上

eureka:
	instance:
    	prefer-ip-address: true

这样注册后， instance_id的值还是不变的， 亦即系讲在Eureka管理页面， 你见到的仍然是
DockerId：spring.application.name: server.port
但是背后里面的地址已经改成ip地址了

但是上图的172.17.0.2 只微服务所在容器内的ip地址。。
这样这个地址还是不能被外部访问的。

解决步骤二

所以我们必须把 容器所在宿主机的ip 注册在Erueka.

对于这点， 我们可以添加配置
eureka.instance.ip-address=xxxxxxx

但是如果这个微服务会被部署到不同的server，或者多个server， 那么我们就不能把上面的配置项hardcode在 配置文件中.

个人建议把这个配置项用传参形式写 DockerFile上。

在DockerFile中最后的CMD 项我们加上这个启动配置项

# for CMD part, only allow ENV variables but not ARG variables
ENV env_jdk_path=$app_folder_path/jdk/bin/java
ENV env_jar_path=$app_folder_path/$app_folder_name/$app_package_name
ENV env_app_server_ip=$app_server_ip
#CMD tail -f /dev/null
CMD $env_jdk_path -jar $env_jar_path --eureka.instance.ip-address=$env_app_server_ip

然后在Jenkins里用Ip 传参给Docker File

                   //copy jdk path, ask dockerfile only could use the files in the directory
                    dir("${workspace_path}/${pom_folder}") {
                        sh "pwd"
                        sh "cp -a ${jdk_path4docker} ."

                        //build docker iamge
                        sh "docker build -t ${docker_repo}:${curr_tag_version} --build-arg app_server_ip=${app_server_ip} ."
                    }

解决步骤三

还有一样， 微服务会吧程序在容器内的端口注册上Eureka.
如果docker 的端口映射是另1个端口的话，还是会连接失败。

个人没找到 Eureka指定注册端口的配置。

所以个人建议只能保证微服务端口和docker容器映射的端口保持一样。

如果做足上面的三点， 我相信用docker微服务 注册Eureka的问题会被解决