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Comment by nodesocket | Hacker News Reader

Is there a cleaner way to drop a user into a shell of a docker container with ports exposed instead of doing:

  services:
    web:
      entrypoint: /bin/bash

And then:

  docker-compose run --service-ports web

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Generally I use

    docker-compose exec <service> sh

I'm not sure what you're asking here - docker/docker-compose have both run and exec - they both start a process in a container. Run creates a new container, exec starts a process in a running container.

Both adhere to entrypoint and cmd; without arguments, entrypoint is called with cmd as argument (eg docker run ngnix would call the entry-script, which would call cmd - together they typically end up running nginx). If an argument is given, cmd is replaced. You would typically want that command to be bash: docker run ngnix bash / docker-compose run ngnix bash.

One difference is that docker-compose uses -ti (--tty/--interactive) by default, plain docker does not.

TL;DR to debug a service while it runs, start it like so:

docker-compose start web

And login to a shell in the container:

docker-compose exec web bash

(with ps you should now see your web server running next to your shell)

To run a shell inside a service, without starting the application itself:

docker-compose run --rm web bash

(your shell is now in a fresh container, your application typically won't be running (if there's no crazy entrypoint/init stuff going on) - and the container will be removed once you exit the shell.

docker-compose exec?

So would just be:

docker-compose exec web /bin/bash

Saves having to add --service-ports

exec only works on specific running containers so you'll need the container id for this

    exec -ti f635776c2d08 /bin/bash

i do this often enough that i keep this in a makefile so i can do it by image name

    docker exec -ti `docker ps | grep 'container-name' | awk '{print $$1}'` /bin/bash

You only need to specify the container by ID if you're using docker directly; if you use docker-compose then you can use the service name and you don't need the `-ti`

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