How to get all ip addresses on a docker network?

Question

I have containers running in a swarm stack of services (on different docker-machines each) connected together on an overlay docker network.

How would it be possible to get all used ip adresses on the network associated with their services or container name from inside a container on this network?

Thank you

Answer 1

If you want to execute this command from inside containers, first you have to mount docker.sock for each service (assuming that docker is installed in the container)

volumes:
  - /var/run/docker.sock:/var/run/docker.sock

then in each container you have to install jq and after that you can simply run docker network inspect <network_name_here> | jq -r 'map(.Containers[].IPv4Address) []' expected output something like:

172.21.0.2/16
172.21.0.5/16
172.21.0.4/16
172.21.0.3/16

Answer 2

1. Find the name OR ID of overlay network -

   $ docker network ls | grep overlay

2. Do a inspect -

   docker inspect $NETWORK_NAME

You will be able to find the container names & IPs allocated to them. You can do a fetch/grep the required values from the inspect output. You will find the output something as below -

    "IPAM": {
        "Driver": "default",
        "Options": null,
        "Config": [
            {
                "Subnet": "172.23.0.0/16",
                "Gateway": "172.23.0.1"
            }
        ]
    },
    "Internal": false,
    "Attachable": true,
    "Ingress": false,
    "ConfigFrom": {
        "Network": ""
    },
    "ConfigOnly": false,
    "Containers": {
        "183584efd63af145490a9afb61eac5db994391ae94467b32086f1ece84ec0114": {
            "Name": "emailparser_lr_1",
            "EndpointID": "0a9d0958caf0fa454eb7dbe1568105bfaf1813471d466e10030db3f025121dd7",
            "MacAddress": "02:42:ac:17:00:04",
            "IPv4Address": "172.23.0.4/16",
            "IPv6Address": ""
        },
        "576cb03e753a987eb3f51a36d4113ffb60432937a2313873b8608c51006ae832": {
            "Name": "emailparser",
            "EndpointID": "833b5c940d547437c4c3e81493b8742b76a3b8644be86af92e5cdf90a7bb23bd",
            "MacAddress": "02:42:ac:17:00:02",
            "IPv4Address": "172.23.0.2/16",
            "IPv6Address": ""
        },