Automate Gitea Docker image publishing

.gitea/workflows/docker.yml

@@ -0,0 +1,49 @@
+name: Build and publish Docker image
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build-and-publish:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out source
+        uses: builtin:checkout
+
+      - name: Log in to Gitea Container Registry
+        env:
+          REGISTRY_USER: ${{ gitea.actor }}
+          REGISTRY_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: printf '%s' "$REGISTRY_TOKEN" | docker login git.anchorhost.eu --username "$REGISTRY_USER" --password-stdin
+
+      - name: Build and tag image
+        env:
+          COMMIT_SHA: ${{ gitea.sha }}
+        run: |
+          image='git.anchorhost.eu/anchorhost.eu/anchorhost-frontend'
+          short_sha="$(printf '%.12s' "$COMMIT_SHA")"
+          docker build \
+            --label "org.opencontainers.image.revision=$COMMIT_SHA" \
+            --tag "$image:main-$short_sha" \
+            --tag "$image:main-latest" \
+            .
+
+      - name: Push image tags
+        env:
+          COMMIT_SHA: ${{ gitea.sha }}
+        run: |
+          image='git.anchorhost.eu/anchorhost.eu/anchorhost-frontend'
+          short_sha="$(printf '%.12s' "$COMMIT_SHA")"
+          docker push "$image:main-$short_sha"
+          docker push "$image:main-latest"
+
+      - name: Log out from Gitea Container Registry
+        if: always()
+        run: docker logout git.anchorhost.eu