gha to build and push a new docker release, if ohmjs/ohm:VERSION doesn't exist

Author: Gary Miller

.github/workflows/docker-release.yml

@@ -0,0 +1,66 @@
+name: Docker Release
+
+# only run this on merge to main
+# clone the repo
+# set the VERSION environment variable ie `cat packages/runtime/package.json | jq -r '.version'`
+# use `docker manifest inspect ohmjs/ohm:$VERION` to verify that the release doesn't already exist before running the rest of the workflow
+# create a multi platfrom builder
+# build and push the image
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+    inputs:
+      VERSION:
+        description: 'Docker image version to build and push'
+        required: false
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Get version
+        id: version
+        run: |
+          if [ -n "${{ inputs.VERSION }}" ]; then
+            echo "VERSION=${{ inputs.VERSION }}" >> "$GITHUB_OUTPUT"
+          else
+            echo "VERSION=$(cat packages/runtime/package.json | jq -r '.version')" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Check if image already exists
+        id: check
+        run: |
+          if docker manifest inspect ohmjs/ohm:${{ steps.version.outputs.VERSION }} > /dev/null 2>&1; then
+            echo "exists=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "exists=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Set up QEMU
+        if: steps.check.outputs.exists == 'false'
+        uses: docker/setup-qemu-action@v4
+
+      - name: Set up Docker Buildx
+        if: steps.check.outputs.exists == 'false'
+        uses: docker/setup-buildx-action@v4
+
+      - name: Log in to Docker Hub
+        if: steps.check.outputs.exists == 'false'
+        uses: docker/login-action@v4
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push
+        if: steps.check.outputs.exists == 'false'
+        uses: docker/bake-action@v7
+        with:
+          files: docker/docker-compose.yml
+          push: true
+        env:
+          VERSION: ${{ steps.version.outputs.VERSION }}