100、神器的 routing mesh （Swarm07）

上一节我们提到了 swarm 的 routing mesh 。当外部访问任意节点的8080端口时，swarm 内部的 load balance 会将请求转发给web_server 其中的一个副本。大概如下图所示：

所以，无论访问哪个节点，及时该节点上没有运行Service的副本，最终都能访问到Service。

另外，我们还可以配置一个外部的 load balance ，将请求路由到 swarm Service 。比如配置HAProxy，将请求分发到各个节点的8080端口。

如下图所示，一共是两层 load balance。

ingress 网络

当我们应用 --publis-add 8080:80 时，swarm 会重新配置service，我们会看到容器发生了以下变化

root@host03:~# docker service create --name web_server --replicas 2 tomcat

v2p0yuexiws1g1qs2xj5hmqte

overall progress: 2 out of 2 tasks

1/2: running [==================================================>]

2/2: running [==================================================>]

verify: Service converged

root@host03:~# docker service ps web_server

ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS

be17grtfyj33 web_server.1 tomcat:latest host02 Running Shutdown 11 seconds ago

wsfub26hj5tq web_server.2 tomcat:latest host01 Running Shutdown 14 seconds ago

root@host01:~# docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

1bb657e47d1f tomcat:latest "catalina.sh run" 16 seconds ago Up 14 seconds 8080/tcp web_server.2.wsfub26hj5tqvufrtvir6nmip

root@host02:~# docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

1183f0b73cba tomcat:latest "catalina.sh run" 19 seconds ago Up 17 seconds 8080/tcp web_server.1.be17grtfyj33nbhyyrhe8dh4c

root@host03:~# docker service update --publish-add 8080:8080 web_server

web_server

overall progress: 2 out of 2 tasks

1/2: running [==================================================>]

2/2: running [==================================================>]

verify: Service converged

root@host03:~# docker service ps web_server

ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS

0y0wh18zbw0l web_server.1 tomcat:latest host02 Running 10 seconds ago

be17grtfyj33 \_ web_server.1 tomcat:latest host02 Shutdown Shutdown 11 seconds ago

lvhvtel79hr8 web_server.2 tomcat:latest host01 Running Running 13 seconds ago

wsfub26hj5tq \_ web_server.2 tomcat:latest host01 Shutdown Shutdown 14 seconds ago

root@host01:~# docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

2fa7f422dfb6 tomcat:latest "catalina.sh run" 24 seconds ago Up 21 seconds 8080/tcp web_server.2.lvhvtel79hr8yw8fzeoaib0u9

1bb657e47d1f tomcat:latest "catalina.sh run" 2 minutes ago Exited (143) 22 seconds ago web_server.2.wsfub26hj5tqvufrtvir6nmip

root@host02:~# docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

b1ba99790519 tomcat:latest "catalina.sh run" 23 seconds ago Up 20 seconds 8080/tcp web_server.1.0y0wh18zbw0lhpks3zbrqdprc

1183f0b73cba tomcat:latest "catalina.sh run" 2 minutes ago Exited (143) 21 seconds ago web_server.1.be17grtfyj33nbhyyrhe8dh4c

root@host01:~# docker exec web_server.2.lvhvtel79hr8yw8fzeoaib0u9 ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo