Docker inspect - Retrieve network's information

The docker inspect command is used to retrieve detailed information about various Docker objects, including images, containers, volumes, networks, and nodes. It provides a comprehensive overview of the object's configuration, state, and other relevant details.

The returned information is a JSON representation of the object.

One use case is to be able to retrieve the name of the network used by a given container.

Some preparation work

Skip this step if you already have a running container

For the illustration, please start a Linux shell and run mkdir -p /tmp/inspect && cd $_.

Create a new index.php file with this content:

<?php

phpinfo();

Then run docker run --name phpinfo -d -p 8080:80 -u ${UID}:${GID} -v "$PWD":/var/www/html php:8.2-apache to create a new Docker container (you can surf to http://localhost:8080 to see it in action).

When running docker container list we can retrieve our container named phpinfo.

Run docker inspect on our container

Now by running docker inspect <container_name> (in our case, docker inspect phpinfo), we'll get a very detailed JSON representation:

[
    {
        "Id": "1243e5a1d063920759525befa6e374fe2a9bc7ae032559877522e59d7afdc6e8",
        "Created": "2023-12-12T07:52:38.480516578Z",
        "Path": "docker-php-entrypoint",
        "Args": [
            "apache2-foreground"
        ],
        [...]
        "NetworkSettings": {
            [...]
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    [...]
                }
            }
            [...]
        }
        [...]
    }
]

The name of the used network can be retrieved in the NetworksSettings.Networks property.

You can retrieve it more easily using this command:

docker inspect phpinfo | jq -r '.[0].NetworkSettings.Networks'

You'll get something like this:

{
  "bridge": {
    "IPAMConfig": null,
    "Links": null,
    "Aliases": null,
    "NetworkID": "efd8b4ee99a7d4283cdfecd122a9357ea8415d3f7cb60b53bda36f1f08d76847",
    "EndpointID": "58ff9063ffdb295ed5b9935a036c2f32225312a3290fdcd90eda96e5f5b6c12b",
    "Gateway": "172.17.0.1",
    "IPAddress": "172.17.0.3",
    "IPPrefixLen": 16,
    "IPv6Gateway": "",
    "GlobalIPv6Address": "",
    "GlobalIPv6PrefixLen": 0,
    "MacAddress": "02:42:ac:11:00:03",
    "DriverOpts": null
  }
}

jq

If you don't have the jq binary yet, please read the The jq utility for Linux article. See my article: The jq utility for Linux.