ci: add docker build

.github/workflows/docker-image.yml

@@ -0,0 +1,50 @@
+name: Docker CI
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*.*.*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to registry
+        uses: docker/login-action@v3
+        with:
+          registry: docker.io       # change to docker.io if using Docker Hub
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            losolio/communitas
+          tags: |
+            type=ref,event=branch
+            type=ref,event=tag
+            type=sha
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          platforms: linux/amd64
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}