GitHub actions: add Docker image build

Author: 31ch

.devcontainer/Dockerfile

@@ -1,7 +1,7 @@
 # https://github.com/devcontainers/images/tree/main/src/cpp
 FROM mcr.microsoft.com/devcontainers/cpp:1-debian-12
 
-# [Optional] Uncomment this section to install additional packages.
+# Install additional packages
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
     && apt-get -y install --no-install-recommends \
         clang-format \

.github/workflows/docker-build-publish.yml

@@ -0,0 +1,38 @@
+name: Build and publish Docker image
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - ".devcontainer/Dockerfile"
+  pull_request:
+    branches:
+      - main
+    paths:
+      - ".devcontainer/Dockerfile"
+
+jobs:
+  build-and-publish:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: "{{defaultContext}}:.devcontainer"
+          push: true
+          tags: ghcr.io/${{ github.repository_owner }}/project-cplusplus:latest