add workflow to publish dev container periodically

.github/workflows/devcontainer.yml

@@ -0,0 +1,41 @@
+name: devcontainer
+
+on:
+  # trigger manually
+  workflow_dispatch:
+
+  # run automatically once a month to update
+  # any changes in the base image
+  schedule:
+  - cron: "0 1 1 * *"
+
+  # update on changes
+  push:
+    paths:
+      - '.devcontainer/**'
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Docker buildx
+        uses: docker/setup-buildx-action@v3
+        with:
+          install: true
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: taiki-e/install-action@just
+      - name: Publish
+        run: just publish-dev-container "$(date +%Y%m%d)"

justfile

@@ -22,6 +22,23 @@ info:
 version TYPE="all":
     @./ci/build_scripts/version.sh {{TYPE}} 2>/dev/null || exit 0
 
+# Publish the dev container to provide more reproducible dev environments
+#
+# docker login ghcr.io
+publish-dev-container TAG="latest" IMAGE="ghcr.io/thin-edge/devcontainer" VARIANT="bookworm" OUTPUT_TYPE="registry":
+    docker buildx install
+    cd .devcontainer && docker buildx build \
+        --platform linux/amd64,linux/arm64,linux/arm/7 \
+        --build-arg "VARIANT={{VARIANT}}" \
+        --label "org.opencontainers.image.version={{VERSION}}-{{VARIANT}}" \
+        --label "org.opencontainers.image.source=https://github.com/thin-edge/thin-edge.io" \
+        -t "{{IMAGE}}:{{TAG}}-{{VARIANT}}" \
+        -t "{{IMAGE}}:latest-{{VARIANT}}" \
+        -f Dockerfile \
+        --output=type="{{OUTPUT_TYPE}}",oci-mediatypes=false \
+        --provenance=false \
+        .
+
 # Default recipe
 [private]
 default: