Networking examples

Show networks

~> docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
ba3e2a49565d        bridge              bridge              local
7e049ea0340c        host                host                local
8375866ba0bb        none                null                local

• --network bridge - Default Docker virtual network, which is NAT'ed behind the Host IP.
• --network host - It gains performance by skipping virtual networks but sacrifices security of container model

Create network

~> docker network create my_app_net
4ce9337a1d89b2cffb7df08c13cf6ef6089a38dcb31f9b88c603a0d98b0992a8

~> docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
ba3e2a49565d        bridge              bridge              local
7e049ea0340c        host                host                local
4ce9337a1d89        my_app_net          bridge              local
8375866ba0bb        none                null                local

Run container on a custom network

~> docker container run -d --name new_nginx --network my_app_net nginx
54456526a198b23339280baceaacc904492a2e826004b159ac9880bbce47822b

Inspect network config

docker network inspect my_app_net

[
    {
        "Name": "my_app_net",
        "Id": "4ce9337a1d89b2cffb7df08c13cf6ef6089a38dcb31f9b88c603a0d98b0992a8",
        "Created": "2017-09-30T12:34:22.7563603Z",
        "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": {
            "54456526a198b23339280baceaacc904492a2e826004b159ac9880bbce47822b": {
                "Name": "new_nginx",
                "EndpointID": "47d02ebd6375e6d5bcb84281a1c0c03e39a6d52c5842846fb79115efd922c096",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {}
    }
]

Attach network to a running container

Check information, grab IDs

~> docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS         NAMES
54456526a198        nginx               "nginx -g 'daemon ..."   5 minutes ago       Up 5 minutes        80/tcp         new_nginx
263eae2f885b        nginx               "nginx -g 'daemon ..."   About an hour ago   Up About an hour    0.0.0.0:80->80/tcp   webhost

~> docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
ba3e2a49565d        bridge              bridge              local
7e049ea0340c        host                host                local
4ce9337a1d89        my_app_net          bridge              local
8375866ba0bb        none                null                local

And now attach

docker network connect 4ce9337a1d89 263eae2f885b

• docker network connect dynamically creates a NIC in a container on an existing virtual network
• docker network disconnect dynamically removes a NIC from a container on a specific virtual network

~> docker container inspect -f '{{range $key, $_ := .NetworkSettings.Networks}}{{println $key}}{{end}}' webhost
bridge
my_app_net

Try to ping between containers inside custom virtual network

• I have 2 custom nginx:alpine versions connected to custom network
  • ping command was removed from default nginx image, thus I had to use nginx:alpine

~> docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS         NAMES
49c23fcf44c0        nginx:alpine        "nginx -g 'daemon ..."   29 minutes ago      Up 29 minutes       80/tcp         new_nginx
0edfeec327ad        nginx:alpine        "nginx -g 'daemon ..."   29 minutes ago      Up 29 minutes       80/tcp         my_nginx

I can easily ping from one to another

~> docker container exec -it my_nginx ping new_nginx
PING new_nginx (172.18.0.3): 56 data bytes
64 bytes from 172.18.0.3: seq=0 ttl=64 time=0.082 ms
64 bytes from 172.18.0.3: seq=1 ttl=64 time=0.047 ms
64 bytes from 172.18.0.3: seq=2 ttl=64 time=0.045 ms
64 bytes from 172.18.0.3: seq=3 ttl=64 time=0.046 ms
64 bytes from 172.18.0.3: seq=4 ttl=64 time=0.045 ms
^C
--- new_nginx ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 0.045/0.053/0.082 ms