Is it possible to start a shell session in a running container (without ssh)

Question

I was naively expecting this command to run a bash shell in a running container :

docker run \"id of running container\" /bin/bash

it look

Answer 1

First thing you cannot run

docker run "existing container" command

Because this command is expecting an image and not a container and it would anyway result in a new container being spawned (so not the one you wanted to look at)

I agree with the fact that with docker we should push ourselves to think in a different way (so you should find ways so that you don't need to log onto the container), but I still find it useful and this is how I work around it.

I run my commands through supervisor in DEAMON mode.

Then I execute what I call docker_loop.sh The content is pretty much this:

#!/bin/bash
/usr/bin/supervisord
/usr/bin/supervisorctl
while ( true )
    do
    echo "Detach with Ctrl-p Ctrl-q. Dropping to shell"
    sleep 1
    /bin/bash
done

What it does is that it allows you to "attach" to the container and be presented with the supervisorctl interface to stop/start/restart and check logs. If that should not suffice, you can Ctrl+D and you will drop into a shell that will allow you to have a peek around as if it was a normal system.

PLEASE DO ALSO TAKE INTO ACCOUNT that this system is not as secure as having the container without a shell, so take all the necessary steps to secure your container.