Dynamically get a running container id/name created by docker run command

Question

So I'm trying to run the following shell script which requires the container id/name of the container (in which the script would be run) dynamically.

One way could be to do docker ps and then getting the Container Id, but that won't be dynamic.

So is there a way to do this dynamically?

#!/bin/bash
docker exec <container id/name> /bin/bash -c "useradd -m <username> -p <password>"

Answer 1

You can give your container a specific name when running it using --name option.

docker run --name mycontainer ...

Then your exec command can use the specified name:

docker exec -it mycontainer ...

Answer 2

You can start your container and store the container id inside a variable like so:

container_id=$(docker run -it --rm --detach busybox)

Then you can use the container id in your docker exec command like so:

docker exec $container_id ls -la

or

docker stop $container_id

Note: Not using a (unique) name for the container but using an ID instead is inspired by this article on how to treat your servers/containers as cattle and not pets