Provide ready-to-use Docker images

[CDDelta]

Same thing as ArweaveTeam/testweave-docker#3

It would be very helpful to have the container image ready to use just by running docker pull. The image can be stored along with this repo using the GitHub Container Registry which is free for OSS.

A GitHub action can be set up to build the image every time a GitHub release is created.

Something like the below will be sufficient. I can't set this up as someone from the team will need to provide a credential for pushing the image to the repo.

For setting up CR_PAT: https://docs.github.com/en/packages/guides/migrating-to-github-container-registry-for-docker-images#authenticating-with-the-container-registry

name: Build Release

on:
  release:
    types: [created]

jobs:
  build_image:
    name: Build image
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
        with:
          ref: ${{ github.head_ref }}
      - name: Cache Docker layers
        uses: actions/cache@v2
        with:
          path: /tmp/.buildx-cache
          key: ${{ runner.os }}-buildx-${{ github.sha }}
          restore-keys: |
            ${{ runner.os }}-buildx-
      - name: Login to GitHub Container Registry
        uses: docker/login-action@v1
        with:
          registry: ghcr.io
          username: ${{ github.repository_owner }}
          password: ${{ secrets.CR_PAT }}   <- The repo owner needs to generate a credential for pushing to the registry
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      - name: Build and push image
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./docker/gateway.dockerfile
          push: true
          tags: |
            ghcr.io/ArweaveTeam/gateway:latest
            ghcr.io/ArweaveTeam/gateway:${{ github.event.release.tag_name }}
          cache-from: type=local,src=/tmp/.buildx-cache
          cache-to: type=local,dest=/tmp/.buildx-cache
      - name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}

[CDDelta]

Also please bind the resulting container images to the repo for ease of access 😄
https://docs.github.com/en/packages/guides/connecting-a-repository-to-a-container-image

[CDDelta]

Instead of using a personal access token, with some config you can now use the built-in GITHUB_TOKEN to authenticate to ghcr.io from GitHub Actions 😄

https://docs.github.com/en/packages/guides/using-github-packages-with-github-actions#upgrading-a-workflow-that-accesses-ghcrio