Getting a Shell in the Docker Desktop Mac VM

docker-for-mac.md

2021 Update: Easiest option is Justin's repo and image

Just run this from your Mac terminal and it'll drop you in a container with full permissions on the Docker VM. This also works for Docker for Windows for getting in Moby Linux VM (doesn't work for Windows Containers).

docker run -it --rm --privileged --pid=host justincormack/nsenter1

more info: https://github.com/justincormack/nsenter1

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Option 1 (hard way): use netcat

nc -U ~/Library/Containers/com.docker.docker/Data/debug-shell.sock

Exit the shell with exit.

Option 2 (easier): Use nsenter in priviledged container

docker run -it --privileged --pid=host debian nsenter -t 1 -m -u -n -i sh

Phil Estes (Docker Maintainer) says:

it’s running a container (using the debian image. nothing special about it other than it apparently has nsenter installed), with pid=host (so you are in the process space of the mini VM running Docker4Mac), and then nsenter says “whatever is pid 1, use that as context, and enter all the namespaces of that, and run a shell there"

Option 3 (easist): run nsenter from a pre-built image. From Justin Cormack (Docker Maintainer)

docker run -it --rm --privileged --pid=host justincormack/nsenter1

I've made a repo :) https://github.com/jbox-web/docker-enter

@n-rodriguez

It is different from docker exec -it CONTAINER_NAME /bin/bash as you enter in the container as root ;)

You could just use

docker exec --user root -it CONTAINER_NAME /bin/bash

:) But writing a script like yours is a good way to learn how containers work.

I would like to make persistent changes to the VM, but after I restart the container they are gone. More specifically, I'm trying to change the proxy environment variables inside the VM. Any chance to make these changes persistent?

When making the changes in the first place, I get Read-only file system on save and fixed it like so.

@rob-weiss that doesn't sound like the best way to set proxy ENVs. 1st, you should be setting those in the Docker Desktop settings under Resources. Then, you should change them in your docker CLI config: https://docs.docker.com/network/proxy/

I am running with userns. It seems that as a result, none of the --privileged solutions work. I receive:
docker: Error response from daemon: privileged mode is incompatible with user namespaces. You must run the container in the host namespace when running privileged mode.

I tried all other solutions in this thread. None work.

Any thoughts on how to get into the underlying VM while in userns mode?

Remove the control sequence like ^[[5;5R from the nc solution: (https://x.com/developerguyba/status/1458109231169691654)

stty -echo -icanon && nc -U ~/Library/Containers/com.docker.docker/Data/debug-shell.sock && stty sane