Update Docker Hub README and keep it in sync with this repository.

[milosgajdos]

This PR

• adds a new docs page (docs/dockerhub.md) that contains the new contents of the README for distribution/distribution Docker Hub repository
• updates the default configuration file that gets baked into the docker image which is published to Docker Hub -- there are a ton of options that produce a lot of logs that confuse the users who are just getting started with the image we distribute via the Docker Hub
• updates the CI with a new workflow job that keeps Docker Hub README in sync with the contents of the docs/dockerhub.md file

Closes #4014

[milosgajdos]

CC: @crazy-max for the CI / GHA review 😄

[crazy-max]

Looks good 👍

[crazy-max]

Oh actually I think you just want to update the README on release or on every push on main?

[milosgajdos]

Ideally everytime we modify the dockerhub readme, so on every merge to main seems like the best thing to do - IF we could do that conditionally thatd be the biggest win

[crazy-max]

Ok then I would suggest a dedicated workflow named dockerhub-readme.yml to update dockerhub readme only when there are changes in the README. Smth like that:

name: dockerhub-readme

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

on:
  push:
    branches:
      - 'main'
    paths:
      - '.github/dockerhub-readme.yml'
      - 'docs/dockerhub.md'

env:
  DOCKERHUB_SLUG: distribution/distribution

jobs:
  update:
    runs-on: ubuntu-latest
    steps:
      -
        name: Update Docker Hub Description
        uses: peter-evans/dockerhub-description@v3
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_PASSWORD }}
          repository: ${{ env.DOCKERHUB_SLUG }}
          readme-filepath: ./docs/dockerhub.md

[milosgajdos]

Ah, yeah, that's much better than my cruft 😅 Let me update

[crazy-max]

LGTM 🚀

[thaJeztah]

Would it make sense to have this page live in either https://github.com/docker/distribution-library-image

or https://github.com/docker-library/docs ?

[milosgajdos]

Would it make sense to have this page live in either https://github.com/docker/distribution-library-image
or https://github.com/docker-library/docs ?

I have thought about it of course but

• https://github.com/docker/distribution-library-image is owned by Docker inc. and would have to be migrated
• https://github.com/docker-library/docs is also part-owned by Docker inc.

Keeping those in sync with Hub from this repo is a fool's errand IMHO, hence this approach

[thaJeztah]

Right, but both those repositories are the ones that are used to publish the image to docker hub, so thought it would probably be the most appropriate location (as this repository itself doesn't publish an image)

[milosgajdos]

this repository itself doesn't publish an image

Wrong. It does, but not an Official image. See the PR. We maintain https://hub.docker.com/r/distribution/distribution and actively push to it.

[thaJeztah]

Wrong. It does, but not an Official image. See the PR.

DOH! My bad I thought this was about the official image 🙈

[milosgajdos]

DOH! My bad I thought this was about the official image 🙈

Can you LGTM this then @thaJeztah 🙃

[thaJeztah]

changes LGTM; can you squash the touch-up commits where needed?

[milosgajdos]

Squashed. Should be goo to go @thaJeztah

[thaJeztah]

LGTM