Inspecting container details in Docker - Commands & Configuration

Introduction

Sometimes you need to see what is happening inside a running container or check its settings. Inspecting container details helps you understand its status, configuration, and resource usage.

When you want to check the IP address or network settings of a running container

When you need to see environment variables or volumes attached to a container

When you want to verify the container's current state and resource limits

When debugging why a container is not behaving as expected

When you want to see logs or the command used to start the container

Commands

This command lists all running containers so you can find the container ID or name to inspect.

Terminal

docker ps

Expected Output

CONTAINER ID   IMAGE          COMMAND                  CREATED         STATUS         PORTS                    NAMES

b1f3c2a4d5e6   nginx:1.23.3   "/docker-entrypoint.…"   2 minutes ago   Up 2 minutes   0.0.0.0:8080->80/tcp     example-nginx

→

-a - Show all containers, including stopped ones

This command shows detailed JSON information about the container named 'example-nginx', including network, volumes, and environment variables.

Terminal

docker inspect example-nginx

Expected Output

[

  {

    "Id": "b1f3c2a4d5e6f7g8h9i0jklmnopqrstuv",

    "Created": "2024-06-01T12:00:00.000000000Z",

    "Path": "/docker-entrypoint.sh",

    "Args": ["nginx", "-g", "daemon off;"],

    "State": {

      "Status": "running",

      "Running": true,

      "Paused": false,

      "Restarting": false,

      "OOMKilled": false,

      "Dead": false,

      "Pid": 12345,

      "ExitCode": 0,

      "StartedAt": "2024-06-01T12:00:05.000000000Z",

      "FinishedAt": "0001-01-01T00:00:00Z"

    },

    "Image": "sha256:abcdef1234567890",

    "NetworkSettings": {

      "IPAddress": "172.17.0.2",

      "Ports": {

        "80/tcp": [

          {

            "HostIp": "0.0.0.0",

            "HostPort": "8080"

          }

        ]

      }

    },

    "Mounts": []

  }

]

This command shows the logs output by the container, useful for debugging or checking what the container is doing.

Terminal

docker logs example-nginx

Expected Output

172.17.0.1 - - [01/Jun/2024:12:01:00 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.68.0"

→

-f - Follow the log output live

Key Concept

If you remember nothing else from this pattern, remember: docker inspect shows all the detailed settings and state of a container in JSON format.

Common Mistakes

Trying to inspect a container using its image name instead of container name or ID

docker inspect requires a container name or ID, not an image name, so it will fail or show wrong info

Use 'docker ps' to find the container name or ID, then run 'docker inspect' with that name or ID

Running 'docker logs' on a container that is not running

If the container is stopped or does not exist, logs command will fail or show no output

Check container status with 'docker ps -a' before running logs

Summary

Use 'docker ps' to list running containers and find the container name or ID.

Use 'docker inspect <container>' to see detailed JSON info about the container's settings and state.

Use 'docker logs <container>' to view the container's output logs for debugging.