Docker images use a user install of Black so don't work when running as another user

[RoryDungan]

Describe the bug

Since bd96139, Docker images use a user install of Black. This means they can't be used when running a container as a user other than root.

This is a problem for me because we run Black inside of Jenkins and Jenkins runs all containers with the same UID as the host, meaning that Black cannot run because it isn't on the PATH and in any case /root/.local/bin/black is inaccessible. It also seems like it could be problematic in any situation where the Black Docker container needs to write a file, because files it creates must be owned by root.

To Reproduce

Previously this would work:

$ docker run --rm -it -u $(id -u):$(id -g) -v $PWD:/workspace -w /workspace pyfound/black:21.9b0 black --check .
All done! ✨ 🍰 ✨
4 files would be left unchanged.

However on versions 21.10b0 and up, including the latest 22.3.0 I get the following output:

$ docker run --rm -it -u $(id -u):$(id -g) -v $PWD:/workspace -w /workspace pyfound/black:21.10b0 black --check .
docker: Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: exec: "black": executable file not found in $PATH: unknown.
$ docker run --rm -it -u $(id -u):$(id -g) -v $PWD:/workspace -w /workspace pyfound/black:22.3.0 black --check .
docker: Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: exec: "black": executable file not found in $PATH: unknown.

Expected behavior

I should be able to run the Black Docker container as any user, not just root.

Environment

• Black's version: 21.10b0, 22.3.0
• OS and Python version: [Linux/Python 3.10.4]

[cooperlees]

Hi - Thanks for reporting. I agree, should be able to run black as non root. We shouldn't promote using root (even this it's in a container) wherever possible.

I guess we just have to remove the pip --user (that I missed when reviewing this) and copy the system install to the actual image.

I'll try look at it soon but happy to take any PR to fix this.