How to start a stopped Docker container with a different command?

Question

I would like to start a stopped Docker container with a different command, as the default command crashes - meaning I can't start the container and then use 'docker exec'.

Basically I would like to start a shell so I can inspect the contents of the container.

Luckily I created the container with the -it option!

Answer 1

Find your stopped container id

docker ps -a

Commit the stopped container:

This command saves modified container state into a new image user/test_image

docker commit $CONTAINER_ID user/test_image

Start/run with a different entry point:

docker run -ti --entrypoint=sh user/test_image

Entrypoint argument description: https://docs.docker.com/engine/reference/run/#/entrypoint-default-command-to-execute-at-runtime

Note:

Steps above just start a stopped container with the same filesystem state. That is great for a quick investigation. But environment variables, network configuration, attached volumes and other staff is not inherited, you should specify all these arguments explicitly.

Steps to start a stopped container have been borrowed from here: (last comment) https://github.com/docker/docker/issues/18078