16 - Docker network第二讲-容器默认网络bridge（Docker系列）

﹏ヽ暗。殇╰゛Y 2022-07-13 07:15 463阅读 0赞

本文章来自[【知识林】][Link 1]

在Docker服务安装成功后默认有三个网络（`docker network ls`）：

C:\Users\zsl-pc>docker network ls
    NETWORK ID          NAME                DRIVER              SCOPE
    992344cd89fe        bridge              bridge              local
    06445f4f5774        host                host                local
    2d964ece79b9        none                null                local

`bridge`：是容器的默认网络，可以配置后与宿主机通信从而与互联网互联互通。

`host`和`none`：是属于无网络（可以使用`docker network inspect host`查看，其中无子网和网关），容器添加到这两个网络时时将容器添加到特定的容器网络堆栈，是不能与外界网络通信的。

**每当使用`docker run`启动一个容器时，这个容器都会有一个默认的网络，即`bridge`。**

可以通过`inspect`命令查看各网络中的容器（查看`bridge`网络）：

C:\Users\zsl-pc>docker network inspect bridge
    [
        {
            "Name": "bridge",
            "Id": "992344cd89fe90aa240651e7497131e5dc40539d3f1ad540f973feab6b345b3c"
            "Scope": "local",
            "Driver": "bridge",
            "EnableIPv6": false,
            "IPAM": {
                "Driver": "default",
                "Options": null,
                "Config": [
                    {
                        "Subnet": "172.17.0.0/16",
                        "Gateway": "172.17.0.1"
                    }
                ]
            },
            "Internal": false,
            "Containers": {},
            "Options": {
                "com.docker.network.bridge.default_bridge": "true",
                "com.docker.network.bridge.enable_icc": "true",
                "com.docker.network.bridge.enable_ip_masquerade": "true",
                "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
                "com.docker.network.bridge.name": "docker0",
                "com.docker.network.driver.mtu": "1500"
            },
            "Labels": {}
        }
    ]

在**Containers**中看到是空，表示目前还没有任何容器加入到这个网络。

**启动容器**：

docker run -d -it --name c1 centos /bin/bash -c "while true; do echo hello; sleep 1; done"

**说明：**启动了一个名为`c1`的Centos的容器，每隔一秒输出`hello`，可以通过`docker logs c1`查看输出信息。

此时再查看`bridge`网络（`docker network inspect bridge`）：

C:\Users\zsl-pc>docker network inspect bridge
    …………
    "Containers": {
        "7883225f9192cb4eb68283fd47bc9435ab70dd76803ede1d926f30db3bb1101f": {
            "Name": "c1",
            "EndpointID": "e784f093b0c810f5c5112235e2e8502f6193077fa5da44a9a527aa9086894382",
            "MacAddress": "02:42:ac:11:00:02",
            "IPv4Address": "172.17.0.2/16",
            "IPv6Address": ""
        }
    }
    …………

**说明：**可以看到`bridge`网络中已经有一个容器`c1`，且IP地址是`172.17.0.2`。

**通过这个例子可以看出在`docker run`启动容器时在未指定网络情况下默认使用了`bridge`这个网络。**

### 在容器中查看网络 ###

C:\Users\zsl-pc>docker exec -it c1 /bin/bash
    [root@7883225f9192 /]# more /etc/hosts
    127.0.0.1       localhost
    ::1     localhost ip6-localhost ip6-loopback
    fe00::0 ip6-localnet
    ff00::0 ip6-mcastprefix
    ff02::1 ip6-allnodes
    ff02::2 ip6-allrouters
    172.17.0.2      7883225f9192
    [root@7883225f9192 /]#

可以看到主机名`7883225f9192`对应的IP地址正是前面所说的`172.17.0.2`。也可通过`ifconfig`查看容器内部的网络信息，如果提示：`bash: ifconfig: command not found`可以先安装网络工具：`yum install -y net-tools`，安装完成后再输入：`ifconfig`

[root@7883225f9192 /]# ifconfig
    eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 172.17.0.2  netmask 255.255.0.0  broadcast 0.0.0.0
            inet6 fe80::42:acff:fe11:2  prefixlen 64  scopeid 0x20<link>
            ether 02:42:ac:11:00:02  txqueuelen 0  (Ethernet)
            RX packets 2057  bytes 7829768 (7.4 MiB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 1873  bytes 105536 (103.0 KiB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
            inet 127.0.0.1  netmask 255.0.0.0
            inet6 ::1  prefixlen 128  scopeid 0x10<host>
            loop  txqueuelen 1  (Local Loopback)
            RX packets 0  bytes 0 (0.0 B)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 0  bytes 0 (0.0 B)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

`eth0`就是这个容器的网卡信息，也可以看出IP地址是`172.17.0.2`。

### 再启动一个容器与其他容器通信 ###

docker run -d -it --name c2 centos /bin/bash -c "while true; do echo hello; sleep 1; done"

**说明：**又启动了一个容器，名称为`c2`，与`c1`做的事情一样。再使用`docker network inspect bridge`可以看到：

C:\Users\zsl-pc>docker network inspect bridge
    …………
    "Containers": {
        "7117f84edc269c5f61052a136791e775e26372c2b977db77081cd78533e5721e": {
            "Name": "c2",
            "EndpointID": "78be5b7b0737d23082607fd016664017df77ceb1d469d9a3972033796ac8d761",
            "MacAddress": "02:42:ac:11:00:03",
            "IPv4Address": "172.17.0.3/16",
            "IPv6Address": ""
        },
        "7883225f9192cb4eb68283fd47bc9435ab70dd76803ede1d926f30db3bb1101f": {
            "Name": "c1",
            "EndpointID": "859ff1ec55e136c5ec431df7baaf42af8f2a3e872a7472e16e392a9fa68d797d",
            "MacAddress": "02:42:ac:11:00:02",
            "IPv4Address": "172.17.0.2/16",
            "IPv6Address": ""
        }
    }
    …………

可以看出：`c1`和`c2`是在一个局域网内，`c2`的IP地址是`172.17.0.3`，可以尝试互相ping一下看是否能ping通：

C:\Users\zsl-pc>docker exec -it c2 /bin/bash
    [root@7117f84edc26 /]# ping -w 4 172.17.0.2
    PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.
    64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.044 ms
    64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.114 ms
    64 bytes from 172.17.0.2: icmp_seq=3 ttl=64 time=0.120 ms
    64 bytes from 172.17.0.2: icmp_seq=4 ttl=64 time=0.121 ms
    64 bytes from 172.17.0.2: icmp_seq=5 ttl=64 time=0.115 ms
    
    --- 172.17.0.2 ping statistics ---
    5 packets transmitted, 5 received, 0% packet loss, time 3996ms
    rtt min/avg/max/mdev = 0.044/0.102/0.121/0.032 ms
    [root@7117f84edc26 /]# exit
    
    C:\Users\zsl-pc>docker exec -it c1 /bin/bash
    [root@7883225f9192 /]# ping -w 4 172.17.0.3
    PING 172.17.0.3 (172.17.0.3) 56(84) bytes of data.
    64 bytes from 172.17.0.3: icmp_seq=1 ttl=64 time=0.048 ms
    64 bytes from 172.17.0.3: icmp_seq=2 ttl=64 time=0.107 ms
    64 bytes from 172.17.0.3: icmp_seq=3 ttl=64 time=0.089 ms
    64 bytes from 172.17.0.3: icmp_seq=4 ttl=64 time=0.113 ms
    64 bytes from 172.17.0.3: icmp_seq=5 ttl=64 time=0.114 ms
    
    --- 172.17.0.3 ping statistics ---
    5 packets transmitted, 5 received, 0% packet loss, time 3996ms
    rtt min/avg/max/mdev = 0.048/0.094/0.114/0.025 ms
    [root@7883225f9192 /]#

**在`c2`里面是可以ping通`c1`的IP地址，在`c1`里面也可以ping通`c2`的IP地址，说明在一个网络下的容器是可以相互通信的。**

本文章来自[【知识林】][Link 1]

[Link 1]: http://www.zslin.com/web/article/detail/63