为什么提供网络功能？

Docker运行通过外部访问容器或容器互联的方式来提供网络服务。

Docker网络配置

当 Docker 启动时，会自动在主机上创建一个 docker0 虚拟网桥，实际上是 Linux 的一个 bridge，可以理解为一个软件交换机。它会在挂载到它的网口之间进行转发。

同时，Docker 随机分配一个本地未占用的私有网段（在 RFC1918 中定义）中的一个地址给 docker0 接口。比如典型的 172.17.42.1，掩码为 255.255.0.0。此后启动的容器内的网口也会自动分配一个同一网段（172.17.0.0/16）的地址。

当创建一个 Docker 容器的时候，同时会创建了一对 veth pair 接口（当数据包发送到一个接口时，另外一个接口也可以收到相同的数据包）。这对接口一端在容器内，即 eth0；另一端在本地并被挂载到 docker0 网桥，名称以 veth 开头（例如 vethAQI2QT）。通过这种方式，主机可以跟容器通信，容器之间也可以相互通信。Docker 就创建了在主机和所有容器之间一个虚拟共享网络。

image-20210211114100062

注意：一般在使用docker网桥(bridge)实现容器与容器通信时，都是站在一个应用角度进行容器通信。

Docker网络相关常用命令

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[root@localhost ~]# docker network --help

Usage:  docker network COMMAND

Manage networks

Commands:
  connect     Connect a container to a network
  create      Create a network
  disconnect  Disconnect a container from a network
  inspect     Display detailed information on one or more networks
  ls          List networks
  prune       Remove all unused networks
  rm          Remove one or more networks

Run 'docker network COMMAND --help' for more information on a command.

1. 查看网络信息

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[root@localhost ~]# docker  network ls
NETWORK ID     NAME      DRIVER    SCOPE
29056e086d3a   bridge    bridge    local
b4ad324721ff   host      host      local
6b4b72694eca   none      null      local

2. 创建一个网桥

  • docker network create -d bridge 网桥名称
  • 简写：docker network create 网桥名称

3. 删除一个网桥

  • docker network rm 网桥名称

4. 容器之前使用网络通信

  1. 查询当前网络配置

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    [root@localhost ~]# docker network ls
    NETWORK ID     NAME      DRIVER    SCOPE
    29056e086d3a   bridge    bridge    local
    b4ad324721ff   host      host      local
    6b4b72694eca   none      null      local

  1. 创建桥接网络

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    [root@localhost ~]# docker network create -d bridge info
    90c876c1ab8e7d842c575946c8255921a6a91ff4e64ff103fc672b039bf2fd3d
    [root@localhost ~]# docker network ls
    NETWORK ID     NAME      DRIVER    SCOPE
    29056e086d3a   bridge    bridge    local
    b4ad324721ff   host      host      local
    90c876c1ab8e   info      bridge    local
    6b4b72694eca   none      null      local

  1. 启动容器指定使用网桥

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    [root@localhost ~]# docker run -d -p 8890:80 --name nginx001 --network info nginx
    4f5955979915e2c2c48fe8d9343134b1303118d28c078d9f368be677fcaec547
    [root@localhost ~]# docker run -d -p 8891:80 --name nginx002 --network info nginx
    e4d910ac3d553cea845a8e7c37e1d8555a02ee79fdcc6ad83c80e0623ceb0b69

    注意:

    • 一旦指定网桥后–name指定名字就是主机名,多个容器指定在同一个网桥时,可以在任意一个容器中使用主机名与容器进行互通
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    [root@localhost ~]# docker ps
    CONTAINER ID   IMAGE           COMMAND                  CREATED          STATUS          PORTS                     NAMES
    e4d910ac3d55   nginx           "/docker-entrypoint.…"   38 seconds ago   Up 37 seconds   0.0.0.0:8891->80/tcp      nginx002
    4f5955979915   nginx           "/docker-entrypoint.…"   58 seconds ago   Up 57 seconds   0.0.0.0:8890->80/tcp      nginx001

    # 进入nginx001这个容器

    使用docker inspect 容器ID查看详细的网络信息

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    [root@localhost ~]# docker inspect e4d910ac3d55
    [
        {
        ……
            "NetworkSettings": {
                "Bridge": "",
                "SandboxID": "99933238d113e0f2daaac850207a7663d3894c43c5b371e085ea8c5576ea0fc4",
                "HairpinMode": false,
                "LinkLocalIPv6Address": "",
                "LinkLocalIPv6PrefixLen": 0,
                "Ports": {
                    "80/tcp": [
                        {
                            "HostIp": "0.0.0.0",
                            "HostPort": "8891"
                        }
                    ]
                },
                "SandboxKey": "/var/run/docker/netns/99933238d113",
                "SecondaryIPAddresses": null,
                "SecondaryIPv6Addresses": null,
                "EndpointID": "",
                "Gateway": "",
                "GlobalIPv6Address": "",
                "GlobalIPv6PrefixLen": 0,
                "IPAddress": "",
                "IPPrefixLen": 0,
                "IPv6Gateway": "",
                "MacAddress": "",
                "Networks": {
                    "info": {
                        "IPAMConfig": null,
                        "Links": null,
                        "Aliases": [
                            "e4d910ac3d55"
                        ],
                        "NetworkID": "90c876c1ab8e7d842c575946c8255921a6a91ff4e64ff103fc672b039bf2fd3d",
                        "EndpointID": "8dfac04ce31ad171f88bdbe17017c5ac96dcbcab02b90c62b516cf6bc718b90d",
                        "Gateway": "172.18.0.1",
                        "IPAddress": "172.18.0.3",
                        "IPPrefixLen": 16,
                        "IPv6Gateway": "",
                        "GlobalIPv6Address": "",
                        "GlobalIPv6PrefixLen": 0,
                        "MacAddress": "02:42:ac:12:00:03",
                        "DriverOpts": null
                    }
                }
            }
        }
    ]
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    [root@localhost ~]# docker inspect 4f5955979915
    [
        {
         ……   
            "NetworkSettings": {
                "Bridge": "",
                "SandboxID": "66470cfa6d26aefadd17f92c69a15332ac4484a9276adceb7e8cc82d02053f17",
                "HairpinMode": false,
                "LinkLocalIPv6Address": "",
                "LinkLocalIPv6PrefixLen": 0,
                "Ports": {
                    "80/tcp": [
                        {
                            "HostIp": "0.0.0.0",
                            "HostPort": "8890"
                        }
                    ]
                },
                "SandboxKey": "/var/run/docker/netns/66470cfa6d26",
                "SecondaryIPAddresses": null,
                "SecondaryIPv6Addresses": null,
                "EndpointID": "",
                "Gateway": "",
                "GlobalIPv6Address": "",
                "GlobalIPv6PrefixLen": 0,
                "IPAddress": "",
                "IPPrefixLen": 0,
                "IPv6Gateway": "",
                "MacAddress": "",
                "Networks": {
                    "info": {
                        "IPAMConfig": null,
                        "Links": null,
                        "Aliases": [
                            "4f5955979915"
                        ],
                        "NetworkID": "90c876c1ab8e7d842c575946c8255921a6a91ff4e64ff103fc672b039bf2fd3d",
                        "EndpointID": "9402be71f181df7c6644ff4d270471fc34f22c54e4c87e1ad653c8801124e233",
                        "Gateway": "172.18.0.1",
                        "IPAddress": "172.18.0.2",
                        "IPPrefixLen": 16,
                        "IPv6Gateway": "",
                        "GlobalIPv6Address": "",
                        "GlobalIPv6PrefixLen": 0,
                        "MacAddress": "02:42:ac:12:00:02",
                        "DriverOpts": null
                    }
                }
            }
        }
    ]

    这是可以查看两个容器间的网络信息，这时我们可以进入其中一个容器，访问另一个容器，验证网络配置后，容器间互通

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    [root@localhost ~]# docker ps
    CONTAINER ID   IMAGE           COMMAND                  CREATED          STATUS          PORTS                     NAMES
    e4d910ac3d55   nginx           "/docker-entrypoint.…"   11 minutes ago   Up 11 minutes   0.0.0.0:8891->80/tcp      nginx002
    4f5955979915   nginx           "/docker-entrypoint.…"   12 minutes ago   Up 12 minutes   0.0.0.0:8890->80/tcp      nginx001
    [root@localhost ~]# docker exec -it e4d910ac3d55 /bin/bash
    root@e4d910ac3d55:/# curl http://172.18.0.2
    <!DOCTYPE html>
    <html>
    <head>
    <title>Welcome to nginx!</title>
    <style>
        body {
            width: 35em;
            margin: 0 auto;
            font-family: Tahoma, Verdana, Arial, sans-serif;
        }
    </style>
    </head>
    <body>
    <h1>Welcome to nginx!</h1>
    <p>If you see this page, the nginx web server is successfully installed and
    working. Further configuration is required.</p>

    <p>For online documentation and support please refer to
    <a href="http://nginx.org/">nginx.org</a>.<br/>
    Commercial support is available at
    <a href="http://nginx.com/">nginx.com</a>.</p>

    <p><em>Thank you for using nginx.</em></p>
    </body>
    </html>
    root@e4d910ac3d55:/#

5. 查看网桥详情

  • docker inspect networkID | name
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[root@localhost ~]# docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
29056e086d3a   bridge    bridge    local
b4ad324721ff   host      host      local
90c876c1ab8e   info      bridge    local
6b4b72694eca   none      null      local
[root@localhost ~]# docker inspect 90c876c1ab8e
[
    {
        "Name": "info",
        "Id": "90c876c1ab8e7d842c575946c8255921a6a91ff4e64ff103fc672b039bf2fd3d",
        "Created": "2021-02-10T22:10:06.936422587+08:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "4f5955979915e2c2c48fe8d9343134b1303118d28c078d9f368be677fcaec547": {
                "Name": "nginx001",
                "EndpointID": "9402be71f181df7c6644ff4d270471fc34f22c54e4c87e1ad653c8801124e233",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            },
            "e4d910ac3d553cea845a8e7c37e1d8555a02ee79fdcc6ad83c80e0623ceb0b69": {
                "Name": "nginx002",
                "EndpointID": "8dfac04ce31ad171f88bdbe17017c5ac96dcbcab02b90c62b516cf6bc718b90d",
                "MacAddress": "02:42:ac:12:00:03",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {}
    }
]