[FEATURE] Hard Coded UID/GID Via Docker Compose

[polskikrol]

Feature Overview

Looks like this image is geared toward those wanting to use the unprivileged mode of NGINX. I use this for all of my containers. Nearly all of them, other projects/solutions, support the following via docker-compose:

    user: '2001:2001'
    group_add:
      - '44'
      - '109'

Additionally, some support setting this via environment variables:

    environment:
      - UID=2002
      - GID=2002

However, here we have this hardcoded. In my situation, I have filesystem locations mounted to keep logging data in addition to being able to easily modify the config (outside of the container) and reload it via inside the container (nginx -s reload).

Alternatives Considered

Another alternative, which is NOT intuitive, and took some time to figure out is the following:

    build:
      context: 'https://github.com/nginx/docker-nginx-unprivileged.git#:mainline/alpine-slim/'
      args:
        UID: 118
        GID: 65534

I have NGINX a system user on the docker host, and override the environment variables (matching the IDs on the host) during my own build referencing the hosted image I want straight from github. Of course, the exposed filesystem locations have this user as the file permission owner.

Additional Context

Whatever way the project wants to go here, I would certainly make sure this is documented better for users. This is a BIG requirement to be able to easily change the UID and GID of the running docker container user.