Add docker-build composite action

README.md

@@ -1,3 +1,56 @@
 # actions-docker
 
-Reusable Docker build+push action for Gitea Actions with buildx and layer caching
+Reusable Gitea Actions for Docker build + push workflows.
+
+## actions/docker-build
+
+Composite action that builds and optionally pushes Docker images with `docker buildx`.
+
+### Usage
+
+```yaml
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: https://gitea.com/actions/checkout@v4
+
+      - name: Build and push
+        uses: https://git.ericxliu.me/eric/actions-docker/.gitea/actions/docker-build@main
+        with:
+          image-name: registry.example.com/myimage
+          dockerfile: Dockerfile
+          context: .
+          push: true
+          cache-from: type=local,src=/tmp/buildx-cache
+          cache-to: type=local,dest=/tmp/buildx-cache,mode=max
+```
+
+### Inputs
+
+| Input | Required | Default | Description |
+|-------|----------|---------|-------------|
+| `dockerfile` | No | `Dockerfile` | Path to Dockerfile relative to `context` |
+| `context` | No | `.` | Build context path |
+| `image-name` | **Yes** | — | Full image name (registry/image) |
+| `tags` | No | (none) | Extra tags as CSV |
+| `platforms` | No | `linux/amd64` | Platforms as CSV |
+| `push` | No | `false` | Push images after build |
+| `cache-from` | No | — | Cache source |
+| `cache-to` | No | `type=local,dest=/tmp/buildx-cache,mode=max` | Cache destination |
+| `build-args` | No | — | Build args as CSV `KEY=VALUE,KEY2=VALUE2` |
+
+### Outputs
+
+| Output | Description |
+|--------|-------------|
+| `image` | Full image name |
+| `tag` | Primary tag (date-SHA) |
+| `digest` | Image digest after push |
+
+### Features
+
+- **Multi-platform** builds via QEMU (if platforms != linux/amd64)
+- **Layer caching** via local buildx cache
+- **Git metadata** — auto-adds `date-SHA` tag + git tag if on a tag ref
+- **`DOCKER_HOST`** — auto-configured for Gitea Actions (`tcp://docker.local:2375`)