Add a docker build step.

.forgejo/workflows/docker.yml

@@ -0,0 +1,86 @@
+name: Docker Build
+
+on:
+  push:
+    branches: [ main, docker ]
+
+env:
+  # Should speed up builds.
+  CARGO_INCREMENTAL: 0
+  # Should reduce the size of ./target to improve cache load/store.
+  CARGO_PROFILE_TEST_DEBUG: 0
+
+jobs:
+  docker-backend:
+    name: Build and Push Backend Image
+    runs-on: docker
+    steps:
+    - name: Checkout Repo
+      uses: https://github.com/actions/checkout@v4
+
+    - name: Set up Docker Buildx
+      uses: https://github.com/docker/setup-buildx-action@v3
+
+    - name: Login to Forgejo Container Registry
+      uses: https://github.com/docker/login-action@v3
+      with:
+        registry: ${{ gitea.server_url }}
+        username: ${{ gitea.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Extract metadata
+      id: meta
+      uses: https://github.com/docker/metadata-action@v5
+      with:
+        images: ${{ gitea.server_url }}/${{ gitea.repository }}/backend
+        tags: |
+          type=ref,event=branch
+          type=sha,prefix={{branch}}-
+          type=raw,value=latest,enable={{is_default_branch}}
+
+    - name: Build and push image
+      uses: https://github.com/docker/build-push-action@v5
+      with:
+        context: ./backend
+        push: true
+        tags: ${{ steps.meta.outputs.tags }}
+        labels: ${{ steps.meta.outputs.labels }}
+        cache-from: type=gha
+        cache-to: type=gha,mode=max
+
+  docker-frontend:
+    name: Build and Push Frontend Image
+    runs-on: docker
+    steps:
+    - name: Checkout Repo
+      uses: https://github.com/actions/checkout@v4
+
+    - name: Set up Docker Buildx
+      uses: https://github.com/docker/setup-buildx-action@v3
+
+    - name: Login to Forgejo Container Registry
+      uses: https://github.com/docker/login-action@v3
+      with:
+        registry: ${{ gitea.server_url }}
+        username: ${{ gitea.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Extract metadata
+      id: meta
+      uses: https://github.com/docker/metadata-action@v5
+      with:
+        images: ${{ gitea.server_url }}/${{ gitea.repository }}/frontend
+        tags: |
+          type=ref,event=branch
+          type=sha,prefix={{branch}}-
+          type=raw,value=latest,enable={{is_default_branch}}
+
+    - name: Build and push image
+      uses: https://github.com/docker/build-push-action@v5
+      with:
+        context: ./frontend
+        push: true
+        tags: ${{ steps.meta.outputs.tags }}
+        labels: ${{ steps.meta.outputs.labels }}
+        cache-from: type=gha
+        cache-to: type=gha,mode=max