認識 Docker bridge network

1. 是否可以透過網路存取其它的 Container。
2. 是否可以存取網際網路(Internet)。
3. 是否可以存取實體網路(Physical Network)。

Docker bridge network 的目的

1. 安全性：不同部門的電腦互相存取。
2. 效率：封包僅在一個網段上運行，不影響別的部門。

使用 Docker bridge network

docker network create --driver bridge alpine-net

$ docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
e9261a8c9a19        alpine-net          bridge              local
17e324f45964        bridge              bridge              local
6ed54d316334        host                host                local
7092879f2cc8        none                null                local

1. alpine1 在 alpine-net 上。
2. alpine2 在 alpine-net 上。
3. alpine3 在 default bridge 上。
4. alpine4 在 alpine-net, default bridge 上。

docker run -dit --name alpine1 --network alpine-net alpine ash
docker run -dit --name alpine2 --network alpine-net alpine ash
docker run -dit --name alpine3 alpine ash
docker run -dit --name alpine4 --network alpine-net alpine ash
docker network connect bridge alpine4

$ docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS              PORTS               NAMES
156849ccd902        alpine              "ash"               41 seconds ago       Up 41 seconds                           alpine4
fa1340b8d83e        alpine              "ash"               51 seconds ago       Up 51 seconds                           alpine3
a535d969081e        alpine              "ash"               About a minute ago   Up About a minute                       alpine2
0a02c449a6e9        alpine              "ash"               About a minute ago   Up About a minute                       alpine1

docker network inspect bridge
[
    {
        "Name": "bridge",
　　　　　...
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.17.0.0/16",
                    "Gateway": "172.17.0.1"
                }
            ]
        },
　　　　 ...
        "Containers": {
            "156849ccd902b812b7d17f05d2d81532ccebe5bf788c9a79de63e12bb92fc621": {
                "Name": "alpine4",
                "EndpointID": "7277c5183f0da5148b33d05f329371fce7befc5282d2619cfb23690b2adf467d",
                "MacAddress": "02:42:ac:11:00:03",
                "IPv4Address": "172.17.0.3/16",
                "IPv6Address": ""
            },
            "fa1340b8d83eef5497166951184ad3691eb48678a3664608ec448a687b047c53": {
                "Name": "alpine3",
                "EndpointID": "5ae767367dcbebc712c02d49556285e888819d4da6b69d88cd1b0d52a83af95f",
                "MacAddress": "02:42:ac:11:00:02",
                "IPv4Address": "172.17.0.2/16",
                "IPv6Address": ""
            }
        },
        "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": {}
    }
]

docker network inspect alpine-net
[
    {
        "Name": "alpine-net",
        ...
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        ...
        "Containers": {
            "0a02c449a6e9a15113c51ab2681d72749548fb9f78fae4493e3b2e4e74199c4a": {
                "Name": "alpine1",
                "EndpointID": "c83621678eff9628f4e2d52baf82c49f974c36c05cba152db4c131e8e7a64673",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            },
            "156849ccd902b812b7d17f05d2d81532ccebe5bf788c9a79de63e12bb92fc621": {
                "Name": "alpine4",
                "EndpointID": "058bc6a5e9272b532ef9a6ea6d7f3db4c37527ae2625d1cd1421580fd0731954",
                "MacAddress": "02:42:ac:12:00:04",
                "IPv4Address": "172.18.0.4/16",
                "IPv6Address": ""
            },
            "a535d969081e003a149be8917631215616d9401edcb4d35d53f00e75ea1db653": {
                "Name": "alpine2",
                "EndpointID": "198f3141ccf2e7dba67bce358d7b71a07c5488e3867d8b7ad55a4c695ebb8740",
                "MacAddress": "02:42:ac:12:00:03",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {}
    }
]

$ docker container attach alpine1
# ping -c 2 alpine2
PING alpine2 (172.18.0.3): 56 data bytes
64 bytes from 172.18.0.3: seq=0 ttl=64 time=0.085 ms
64 bytes from 172.18.0.3: seq=1 ttl=64 time=0.090 ms
--- alpine2 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.085/0.087/0.090 ms

# ping -c 2 alpine3
ping: bad address 'alpine3'

$ docker container attach alpine4
# ping -c 2 alpine1
PING alpine1 (172.18.0.2): 56 data bytes
64 bytes from 172.18.0.2: seq=0 ttl=64 time=0.074 ms
64 bytes from 172.18.0.2: seq=1 ttl=64 time=0.082 ms
--- alpine1 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.074/0.078/0.082 ms