How to retain docker alpine container after "exit" is used?

Question

Like for example if I use command docker run -it alpine /bin/sh it starts a terminal after which I can install packages and all. Now when I use exit command it goes back to the terminal. (main one)

So how can I access the same container again? When I run that command again, I get a fresh alpine.

Please help

Answer 1

The container lives as long as the specified run command process is still running. When you specify to run /bin/sh, once you exit, the sh process will die and so will you container.

If you want to keep your container running, you have to keep the process inside running. For your case (I am not sure what you want to acheive, I assume you are just testing), the following will keep it running

docker run -d --name alpine alpine tail -f /dev/null

Then you can sh into the container using

docker exec -it alpine sh  

Answer 2

Pull an image

docker image pull alpine

See that image is there

docker image ls   OR  just docker images

see what is inside the alpine

docker run alpine ls -al

Now your question is how to stay with the shell

docker container run -it alpine /bin/sh

You are inside shell script command line. Some distribution may have bash shell.

 docker exec -it 5f4 sh
 / # (<-- you can run linux command here!)

At this point, you can use command line of alpine and do

ls -al

type exit to come out- You can run it in detached mode and it will keep running.

With exec command we can login again

docker container run -it -d alpine /bin/sh

verify that it is UP and copy the FIRST 2 -3 digits of the container ID

docker container ls

login with exec command

docker exec -it <CONTAINER ID or just 2-3 digits> sh

You will need to STOP otherwise it will keep running.

docker stop <CONTAINER ID>