关于docker:44-容器之间的link

应用–link来连贯容器

https://docs.docker.com/netwo…

Warning: The –link flag is a legacy feature of Docker. It may eventually be removed. Unless you absolutely need to continue using it, we recommend that you use user-defined networks to facilitate communication between two containers instead of using –link. One feature that user-defined networks do not support that you can do with –link is sharing environmental variables between containers. However, you can use other mechanisms such as volumes to share environment variables between containers in a more controlled way.

删除原有的test2容器，而后从新创立一个，应用–link选项连贯test1容器

docker run -d --name test2 --link test1 busybox /bin/sh -c "while true;do sleep 3600;done"

目前test1与test2的ip别离为172.17.0.2/16，172.17.0.3/16。
因为创立test2容器的时候，应用了–link，如下两种形式都是等价的。
但第二种形式的益处是：

• 它能够让咱们在解决业务逻辑的时候不必关怀连贯的内部容器的ip到底是什么。
• 假如咱们设置的db内部的容器重启之后IP变了，这个

docker exec -it test2 ping 172.17.0.2
docker exec -it test2 ping test1

–link并不是双向的，想在test1上应用name来ping通test2就是不行的

#ok
docker exec -it test1 ping 172.17.0.3
#failure
docker exec -it test1 ping test2

手动建设bridge网络

做完上述的link试验之后，删掉test2容器，回过头查看一下docker网络

[vagrant@docker-node1 ~]$ docker network ls
NETWORK ID NAME DRIVER SCOPE
a61c325bd7ba bridge bridge local
efb6975c8935 host host local
3fa0f2e1a00b none null local

而后咱们本人新建一个bridge网络

docker network create -d bridge my-bridge

建完之后，网络列表是这样的：

[vagrant@docker-node1 ~]$ docker network ls
NETWORK ID NAME DRIVER SCOPE
a61c325bd7ba bridge bridge local
efb6975c8935 host host local
4213425c5293 my-bridge bridge local
3fa0f2e1a00b none null local

应用brctl show命令查看，后果如下

而后新建一个test3容器，使它连贯到咱们手动建设的my-bridge网络

docker run -d --name test3 --network my-bridge busybox /bin/sh -c "while true;do sleep 3600;done"

此时再应用brctl show命令，就能够查看到my-bridge网络的veth接口了

应用docker network inspect 4213425c5293命令，也能看到该网络下的test3容器了

{
    "Containers": {
        "b9716e4b50ddb4800a03bd04530eea086331493a50fa1dffbcdcadad1801ba58": {
            "Name": "test3",
            "EndpointID": "ee2124e316486c522ba5414fb5bfd4fc463f45c22e944d65a0028fbcacf39794",
            "MacAddress": "02:42:ac:12:00:02",
            "IPv4Address": "172.18.0.2/16",
            "IPv6Address": ""
        }
    }
}

而后咱们再让test1在连贯name为bridge的网络的根底上，使它还能够连贯到my-bridge

docker network connect my-bridge test1

此时test1就同时连贯到bridge和my-bridge两个网络上了。
name为bridge的网络

docker network inspect a61c325bd7ba
{
    "Containers": {
        "5b567458c87cc1c7eff73d47a753e1171c6478f2705868f01ebd858b196a2283": {
            "Name": "test1",
            "EndpointID": "e6710f0db01bdbf3669aabeab866a4f27bf1605226dd3d3c98a8b7ea1c6896f0",
            "MacAddress": "02:42:ac:11:00:02",
            "IPv4Address": "172.17.0.2/16",
            "IPv6Address": ""
        }
    }
}

name为my-bridge的网络

docker network inspect 4213425c5293
{
    "Containers": {
        "5b567458c87cc1c7eff73d47a753e1171c6478f2705868f01ebd858b196a2283": {
            "Name": "test1",
            "EndpointID": "a12ab3ef7cdb07c4cd6cb7bd7f5114e6b05107b19de0240abe1f704d46d8afae",
            "MacAddress": "02:42:ac:12:00:03",
            "IPv4Address": "172.18.0.3/16",
            "IPv6Address": ""
        },
        "b9716e4b50ddb4800a03bd04530eea086331493a50fa1dffbcdcadad1801ba58": {
            "Name": "test3",
            "EndpointID": "ee2124e316486c522ba5414fb5bfd4fc463f45c22e944d65a0028fbcacf39794",
            "MacAddress": "02:42:ac:12:00:02",
            "IPv4Address": "172.18.0.2/16",
            "IPv6Address": ""
        }
    }
}

而后做如下测试，发现test1和test3都是能够ping通的，至于为啥没有应用–link选项也能通过name来ping通，而且还是双向ping通呢？

这是因为docker容器只有不是退出默认的bridge网络，而是自定义的bridge网络，容器之间都是能够相互ping通的

docker exec test1 ping test3
docker exec test1 ping 172.18.0.2
docker exec test3 ping test1
docker exec test3 ping 172.18.0.3

至于如下ping失败的起因，则是test1尽管有两个ip，并且和test3有互通的网络，然而这两个ip齐全不在一个网段上了。

docker exec test3 ping 172.17.0.2