Add GHA workflow to build and push Docker images

.github/workflows/build-images.yml

@@ -0,0 +1,80 @@
+name: Build and publish Docker images
+
+on:
+  push:
+    branches:
+      - main
+      - devel
+      - specky
+    paths:
+      - "env/*/Dockerfile"
+      - "env/*/environment.yml"
+
+env:
+  REGISTRY: ghcr.io
+  INCLUDE_DIR: "env/"
+  REPOSITORY: ${{ github.repository }}
+
+jobs:
+  changed-directories:
+    name: Get last directory name of changed files
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.changed-files.outputs.all_changed_files }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Get changed files
+        uses: tj-actions/changed-files@v45
+        id: changed-files
+        with:
+          matrix: true
+          dir_names: true
+          path: ${{ env.INCLUDE_DIR }}
+          dir_names_include_files: ${{ env.INCLUDE_DIR }}
+          dir_names_exclude_current_dir: true
+
+  build-and-push-image:
+    name: Build and push Docker images
+    runs-on: ubuntu-latest
+    needs: changed-directories
+    strategy:
+      fail-fast: false
+      matrix:
+        name: ${{ fromJSON(needs.changed-directories.outputs.matrix) }}
+        platform: [linux/amd64, linux/arm64]
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Extract metadata for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.REPOSITORY }}/${{ matrix.name }}
+          tags: |
+            type=raw,value=latest,enable=${{ endsWith(github.ref, github.event.repository.default_branch) }}
+            type=ref,event=branch,enable=${{ !endsWith(github.ref, github.event.repository.default_branch) }}
+          flavor: |
+            latest=false
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: ${{ env.INCLUDE_DIR }}/${{ matrix.name }}
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          platforms: ${{ matrix.platform }}