Path is not mounted correctly when running Docker hooks from Docker

Situation:

In our CI we want to run pre-commit inside Docker.
Some of our hooks are docker_image

Problem
This line mostly

pre-commit/pre_commit/languages/docker.py

Line 94 in 528c7af

'-v', f'{os.getcwd()}:/src:rw,Z',

Currently pre-commit mounts the current directory to /src and uses current directory name as mount base.
However this does not work when pre-commit is run inside the container on some mounted path already, because mount points are relative to the host, not to the container.

Example:

/opt/my_code      <- host, mounts /opt/my_code:/project
/project              <- in Docker running pre-commit, pre-commit is doing mount /project:/src
/src                   <-  (in Dockerized hook)

Currently pre-commit will try to mount it as -v /project:/src,rw,Z. Expected - to mount it as -v /opt/my_code:/src

Possible solution:

When I replaced os.getcwd() from the code above to translate_path(os.getcwd()) where translate_path is taken from https://gist.github.com/dpfoose/f96d4e4b76c2e01265619d545b77987a, it worked perfectly. It does add extra docker pip-dependency though.

See also: https://forums.docker.com/t/mounting-a-volume-not-working-with-running-docker-in-docker/25775/2

the docker* hook type assume you're on the host -- changing that breaks some of our assumptions but it might be possible to implement your suggestion

the call into docker-py can be replaced with subprocess.check_call(('docker', 'inspect', hostname)) -- would you like to take a stab at fixing it?

@okainov

@okainov would you be interested in working on this?

@asottile

@asottile I'd really like to and I have also the update for not using docker dependency, but there might be some bureaucracy issues from my side, so I'm not sure whether I could publish it soon...

Is there any appetite for mounting in a similar way to jenkins, where the docker container essentially becomes transparent since it would be mounted like so:

-v os.getcwd():os.getcwd()

that would be a breaking change from the current set of guarantees

@asottile

@asottile it took me some time :D But here is PR #1885, feel free to take a look and provide feedback.

fix: fix path mounting when running in Docker

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Path is not mounted correctly when running Docker hooks from Docker #1387

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Path is not mounted correctly when running Docker hooks from Docker #1387

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asottile commented on Apr 6, 2020

asottile commented on Apr 22, 2020

okainov commented on Apr 23, 2020

djh82 commented on Oct 3, 2020

asottile commented on Oct 4, 2020

okainov commented on Apr 21, 2021

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