docker命令之link

1.新建两台容器，第二台(busybox_2)link到第一台(busybox_1)

[root@localhost ~]# docker run -d -it --name busybox_1 busybox /bin/sh -c "while true;do sleep 3600;done"
8240c9aa04e3b5653c6747ae13a4e4478eb8e62060e4c8644492dbbf5c71c734
[root@localhost ~]# docker run -d -it --name busybox_2 --link busybox_1 busybox /bin/sh -c "while true;do sleep 3600;done"
9131353a28de9c0816121f0960644275d789e4dfe136a00cff6b0d9850b35c7e

2.获取两台容器的IP地址

[root@localhost ~]# docker exec -it busybox_1 ip a|grep 172
inet 172.17.0.2/16 scope global eth0
[root@localhost ~]# docker exec -it busybox_2 ip a|grep 172
inet 172.17.0.3/16 scope global eth0

3.分别在两台容器上通过ip和容器名称ping另一台容器，注意查看结果

[root@localhost ~]# docker exec -it busybox_1 ping -c  172.17.0.3
PING 172.17.0.3 (172.17.0.3):  data bytes
 bytes from 172.17.0.3: seq= ttl= time=0.079 ms
[root@localhost ~]# docker exec -it busybox_1 ping -c  buxybox_2
ping: bad address 'buxybox_2'

[root@localhost ~]# docker exec -it busybox_2 ping -c  172.17.0.2
PING 172.17.0.2 (172.17.0.2):  data bytes
 bytes from 172.17.0.2: seq= ttl= time=0.089 ms
[root@localhost ~]# docker exec -it busybox_2 ping -c  busybox_1
PING busybox_1 (172.17.0.2):  data bytes
 bytes from 172.17.0.2: seq= ttl= time=0.088 ms

4.删除被link的容器，查看结果

[root@localhost ~]# docker rm -f busybox_1
busybox_1
[root@localhost ~]# docker exec -it busybox_2  ping busybox_1
Error response from daemon: Cannot link to a non running container: /busybox_1 AS /busybox_2/busybox_1
[root@localhost ~]# docker run -d -it --name busybox_1 busybox /bin/sh -c "while true;do sleep 3600;done"
74088ba7c2f9db67a607185d9a0b2157098036c1a2ca7b200c41ec04685f1210
[root@localhost ~]# docker exec -it busybox_2  ip a
Error response from daemon: Cannot link to a non running container: /busybox_1 AS /busybox_2/busybox_1

5.查看当前docker 可使用网络

[root@localhost ~]# docker network ls  #如果容器没有显示指定使用的网络，默认使用bridge
NETWORK ID          NAME                DRIVER              SCOPE
fa30a4d17b5b        bridge              bridge              local
a03aaca35833        host                host                local
d85c50eb947c        none                null                local

6.手动创建一个docker网络

[root@localhost ~]#  docker network create -d bridge my_bridge  #-d 指定类型 my_bridge为名称
652b4f64a3bc7691e8b65a8a7508e83e7585cde9d698438bc971a3c63bd6d62d

7.验证是否创建成功

[root@localhost ~]# docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
fa30a4d17b5b        bridge              bridge              local
a03aaca35833        host                host                local
652b4f64a3bc        my_bridge           bridge              local
d85c50eb947c        none                null                local

[root@localhost ~]# brctl show
bridge name             bridge id        STP enabled    interfaces
br-652b4f64a3bc        .0242a1ad4372    no              #652...即my_bridge的ID,当前没有被连接
docker0                .024223c091f9    no          veth54f7336
                                                        veth7ca4b55

8.新建一个容器，使用我们刚刚新建的my_bridge网络

[root@localhost ~]# docker run -d -it --name busybox_3 --network my_bridge  busybox /bin/sh -c "while true;do sleep 3600;done"
749b800c24708539fefbc462bbf4463fde5cdbd7b6e8787383e586342fc2977b   #使用 --network指定网络

9.验证刚刚的操作

[root@localhost ~]# brctl show
bridge name   　　　　　　 bridge id        STP enabled    interfaces
br-652b4f64a3bc        .0242a1ad4372    no          veth72d2357
docker0        　　　　 .024223c091f9    no          veth54f7336
                            　　　　　　　　　　　　　　　　 veth7ca4b55

[root@localhost ~]# docker network inspect my_bridge
......
"Containers": {
            "749b800c24708539fefbc462bbf4463fde5cdbd7b6e8787383e586342fc2977b": {
                "Name": "busybox_3",  #名称
                "EndpointID": "22aac7ec5076908c40ebc8175bd307b6174b94f709240743d36540fe90220c1b",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",   #IP地址，发现其网段为18，与之前创建的容器网段不同
                "IPv6Address": ""
            }
        },
......

10.将已存在的容器加入my_bridge网络并验证

[root@localhost ~]# docker network connect my_bridge busybox_2
[root@localhost ~]# docker network inspect my_bridge
......
        "Containers": {
            "749b800c24708539fefbc462bbf4463fde5cdbd7b6e8787383e586342fc2977b": {
                "Name": "busybox_3",
                "EndpointID": "22aac7ec5076908c40ebc8175bd307b6174b94f709240743d36540fe90220c1b",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            },
            "9131353a28de9c0816121f0960644275d789e4dfe136a00cff6b0d9850b35c7e": {
                "Name": "busybox_2",
                "EndpointID": "e2fbd16d9a6ba1495a4e9907153e0dae619f172c70f890382b1007d0f4d7e6a6",
                "MacAddress": "02:42:ac:12:00:03",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            }
        },
......

[root@localhost ~]# brctl show
bridge name    　       　bridge id        STP enabled    interfaces
br-652b4f64a3bc        .0242a1ad4372    no          veth72d2357
                                                        veth798a93a
docker0                .024223c091f9    no          veth54f7336
                                                        veth7ca4b55

11.基于当前的网络状态，测试各容器之间的网络通信状态，主要观察结果

当前的容器名称及IP为：
name:busybox_1    IP：172.17.0.2/(bridge)
name:busybox_2    IP：172.17.0.3/(bridge) 172.18.0.3/(my_bridge)
name:busybox_3    IP：172.18.0.2/(my_bridge)

在busybox_1上:
[root@localhost ~]# docker exec -it busybox_1 ping -c  172.17.0.3
[root@localhost ~]# docker exec -it busybox_1 ping -c  172.18.0.3
[root@localhost ~]# docker exec -it busybox_1 ping -c  172.18.0.2
[root@localhost ~]# docker exec -it busybox_1 ping -c  busybox_2
[root@localhost ~]# docker exec -it busybox_1 ping -c  busybox_3

在busybox_2上:
[root@localhost ~]# docker exec -it busybox_2  ping -c  172.17.0.2
[root@localhost ~]# docker exec -it busybox_2  ping -c  172.18.0.2
[root@localhost ~]# docker exec -it busybox_2  ping -c  busybox_1
[root@localhost ~]# docker exec -it busybox_2  ping -c  busybox_3

在busybox_3上:
[root@localhost ~]# docker exec -it busybox_3  ping -c  172.17.0.2
[root@localhost ~]# docker exec -it busybox_3  ping -c  172.17.0.3
[root@localhost ~]# docker exec -it busybox_3  ping -c  172.18.0.3
[root@localhost ~]# docker exec -it busybox_3  ping -c  busybox_1
[root@localhost ~]# docker exec -it busybox_3  ping -c  busybox_2

12.新建一个容器，使用my_bridge网络

[root@localhost ~]# docker run -d -it --name busybox_4 --network my_bridge  busybox /bin/sh -c "while true;do sleep 3600;done"
c831ad0d4f25ab7b8d44904ea9cb9c1cff3ddb842043b070dbabe8be1df38d75

13.测试最后新建容器与其他容器的网络通信

[root@localhost ~]# docker exec -it busybox_4  ping -c  172.18.0.1
[root@localhost ~]# docker exec -it busybox_4  ping -c  172.18.0.2
[root@localhost ~]# docker exec -it busybox_4  ping -c  172.18.0.3
[root@localhost ~]# docker exec -it busybox_4  ping -c  busybox_1
[root@localhost ~]# docker exec -it busybox_4  ping -c  busybox_2
[root@localhost ~]# docker exec -it busybox_4  ping -c  busybox_3

总结：

1.当我们新建容器时，如果没有显示指定其使用的网络，那么默认会使用bridge网络
2.当一个容器link到另一个容器时，该容器可以通过IP或容器名称访问被link的容器，而被link容器可以通过IP访问该容器，但是无法通过容器名称访问
3.当被link的容器被删除时，创建link的容器也无法正常使用
4.如果两个容器被加入到我们手动创建的网络时，那么该网络内的容器相互直接可以通过IP和名称同时访问。