Create a workflow for publishing new ruby versions

When new ruby versions are released, we want to publish new versions of the existing images for those ruby versions, rather than cut a new version of the image. So let's create a manually GH workflow that publishes a list of ruby versions for a list of image tags.

.github/actions/build-and-publish-image/action.yml

@@ -0,0 +1,49 @@
+name: Build and Publish Image
+description: Steps for building an image for a specific ruby version
+inputs:
+  ruby_version:
+    required: true
+  image_tag:
+    required: true
+  gh_token:
+    required: true
+  repository_owner:
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Checkout (GitHub)
+      uses: actions/checkout@v3
+      with:
+        ref: ${{ inputs.image_tag }}
+
+    - name: Set up QEMU for multi-architecture builds
+      uses: docker/setup-qemu-action@v3
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+      with:
+        platforms: linux/amd64,linux/arm64
+
+    - name: Set Image version env variable
+      run: echo "IMAGE_VERSION=$(echo ${{ inputs.image_tag }} | tr -d ruby-)" >> $GITHUB_ENV
+      shell: bash
+
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v2
+      with:
+        registry: ghcr.io
+        username: ${{ inputs.repository_owner }}
+        password: ${{ inputs.gh_token }}
+
+    - name: Pre-build Dev Container Image
+      uses: devcontainers/[email protected]
+      env:
+        RUBY_VERSION: ${{ inputs.ruby_version }}
+        BUILDX_NO_DEFAULT_ATTESTATIONS: true
+      with:
+        imageName: ghcr.io/rails/devcontainer/images/ruby
+        imageTag: ${{ env.IMAGE_VERSION }}-${{ inputs.ruby_version }},${{ inputs.ruby_version }}
+        subFolder: images/ruby
+        push: always
+        platform: linux/amd64,linux/arm64

.github/workflows/publish-new-image-version.yaml

@@ -0,0 +1,47 @@
+name: Build and Publish Images
+
+on:
+  push:
+    tags: [ 'ruby-*.*.*' ]
+
+jobs:
+  build:
+    name: Build Images
+
+    strategy:
+      fail-fast: false
+      matrix:
+        RUBY_VERSION:
+          - 3.3.0
+          - 3.2.3
+          - 3.2.2
+          - 3.2.1
+          - 3.2.0
+          - 3.1.4
+          - 3.1.3
+          - 3.1.2
+          - 3.1.1
+          - 3.1.0
+          - 3.0.6
+          - 3.0.5
+          - 3.0.4
+          - 3.0.3
+          - 3.0.2
+          - 3.0.1
+          - 3.0.0
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout (GitHub)
+        uses: actions/checkout@v3
+
+      - name: Build and Publish Image
+        uses: ./.github/actions/build-and-publish-image.yml
+        with:
+          ruby_version: ${{ matrix.RUBY_VERSION }}
+          image_tag:  ${{ github.ref_name }}
+          gh_token: ${{ secrets.GITHUB_TOKEN }}
+          repository_owner: ${{ github.repository_owner }}

.github/workflows/publish-new-ruby-versions.yml

@@ -0,0 +1,39 @@
+name: Build and Publish New Ruby Versions
+
+on:
+  workflow_dispatch:
+    inputs:
+      ruby_versions:
+        type: string
+        required: true
+        description: List of ruby versions to build. Should be an array ["3.3.1","3.2.4"]
+      image_versions:
+        type: string
+        required: true
+        description: List of image versions to build. Should be an array ["ruby-0.3.0"]
+
+jobs:
+  build:
+    name: Build Images
+
+    strategy:
+      fail-fast: false
+      matrix:
+        RUBY_VERSION:  ${{ fromJSON(github.event.inputs.ruby_versions)}}
+        IMAGE_VERSION:  ${{ fromJSON(github.event.inputs.image_versions)}}
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout (GitHub)
+        uses: actions/checkout@v3
+
+      - name: Build and Publish Image
+        uses: ./.github/actions/build-and-publish-image.yml
+        with:
+          ruby_version: ${{ matrix.RUBY_VERSION }}
+          image_tag:  ${{ matrix.IMAGE_VERSION }}
+          gh_token: ${{ secrets.GITHUB_TOKEN }}
+          repository_owner: ${{ github.repository_owner }}

CONTRIBUTING.md

@@ -38,4 +38,16 @@ the same process as for features.
 
 The image is published using the [devcontainers/ci](https://github.com/devcontainers/ci) Github Action. This workflow
 is kicked off by the creation of a new tag on Github. Tags should be in the form `ruby-*.*.*`, where the * represent
-the **image version** (not the ruby version). Images will be published for all `3.*.*` ruby versions.
+the **image version** (not the ruby version). Images will be published for all `3.*.*` ruby versions.
+
+## Publishing new Ruby versions
+
+When a new Ruby version is released, we can build and publish the existing image for the new ruby version, without
+needing to cut a new version of the image itself. To do this, we can run the Publish New Ruby Versions workflow
+manually. The workflow takes a list of a ruby versions and a list of image tags as inputs. They should be formatted
+as comma separated arrays. For example:
+
+```
+ruby_versions: ["3.3.1","3.2.4","3.1.5","3.0.7"]
+image_versions: ["ruby-0.3.0"]
+```