feat: add official Docker image with GHCR publishing workflow

- Add docker/Dockerfile with non-root user and configurable environment
- Add GitHub Actions workflow to build multi-platform images (amd64/arm64)
- Publish to ghcr.io/benoitc/gunicorn on version tags
- Update documentation with official image usage examples

.github/workflows/docker-publish.yml

@@ -0,0 +1,57 @@
+name: Docker Publish
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push:
+    name: Build and Push Docker Image
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - 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 Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=raw,value=latest,enable={{is_default_branch}}
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: docker/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

docker/.dockerignore

@@ -0,0 +1,8 @@
+.git
+.github
+__pycache__
+*.pyc
+.pytest_cache
+.tox
+docs
+tests

docker/Dockerfile

@@ -0,0 +1,31 @@
+FROM python:3.12-slim
+
+LABEL org.opencontainers.image.source=https://github.com/benoitc/gunicorn
+LABEL org.opencontainers.image.description="Gunicorn Python WSGI HTTP Server"
+LABEL org.opencontainers.image.licenses=MIT
+
+# Create non-root user
+RUN useradd --create-home --shell /bin/bash gunicorn
+
+WORKDIR /app
+
+# Install gunicorn
+RUN pip install --no-cache-dir gunicorn
+
+# Copy entrypoint script
+COPY docker/docker-entrypoint.sh /usr/local/bin/
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+
+# Configuration via environment:
+#   GUNICORN_BIND    - full bind address (default: [::]:8000, IPv4+IPv6)
+#   GUNICORN_HOST    - bind host (default: [::])
+#   GUNICORN_PORT    - bind port (default: 8000)
+#   GUNICORN_WORKERS - number of workers (default: number of CPUs)
+#   GUNICORN_ARGS    - additional arguments (e.g., "--timeout 120")
+
+USER gunicorn
+
+EXPOSE 8000
+
+ENTRYPOINT ["docker-entrypoint.sh"]
+CMD ["--help"]

docker/docker-entrypoint.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+set -e
+
+# Allow running other commands (e.g., bash for debugging)
+if [ "${1:0:1}" = '-' ] || [ -z "${1##*:*}" ]; then
+    # First arg is a flag or contains ':' (app:callable), run gunicorn
+
+    # Build bind address from GUNICORN_HOST and GUNICORN_PORT, or use GUNICORN_BIND
+    # Default: listen on both IPv4 and IPv6
+    PORT="${GUNICORN_PORT:-8000}"
+    BIND="${GUNICORN_BIND:-${GUNICORN_HOST:-[::]}:${PORT}}"
+
+    # Add bind if not specified in args or GUNICORN_ARGS
+    if [[ ! " $* $GUNICORN_ARGS " =~ " --bind " ]] && [[ ! " $* $GUNICORN_ARGS " =~ " -b " ]] && [[ ! "$* $GUNICORN_ARGS" =~ --bind= ]] && [[ ! "$* $GUNICORN_ARGS" =~ -b= ]]; then
+        set -- --bind "$BIND" "$@"
+    fi
+
+    # Add workers if not specified - default to number of CPUs
+    if [[ ! " $* $GUNICORN_ARGS " =~ " --workers " ]] && [[ ! " $* $GUNICORN_ARGS " =~ " -w " ]] && [[ ! "$* $GUNICORN_ARGS" =~ --workers= ]] && [[ ! "$* $GUNICORN_ARGS" =~ -w= ]]; then
+        WORKERS="${GUNICORN_WORKERS:-$(nproc)}"
+        set -- --workers "$WORKERS" "$@"
+    fi
+
+    # Append GUNICORN_ARGS if set
+    if [ -n "$GUNICORN_ARGS" ]; then
+        exec gunicorn $GUNICORN_ARGS "$@"
+    fi
+
+    exec gunicorn "$@"
+fi
+
+# Otherwise, run the command as-is (e.g., bash, sh, python)
+exec "$@"

docs/content/guides/docker.md

@@ -4,6 +4,81 @@ Running Gunicorn in Docker containers is the most common deployment pattern
 for modern Python applications. This guide covers best practices for
 containerizing Gunicorn applications.
 
+## Official Docker Image
+
+Gunicorn provides an official Docker image on GitHub Container Registry:
+
+```bash
+docker pull ghcr.io/benoitc/gunicorn:latest
+```
+
+### Quick Start
+
+Mount your application directory and run:
+
+```bash
+docker run -p 8000:8000 -v $(pwd):/app ghcr.io/benoitc/gunicorn app:app
+```
+
+### Environment Variables
+
+| Variable | Description | Default |
+|----------|-------------|---------|
+| `GUNICORN_BIND` | Full bind address | `[::]:8000` (IPv4+IPv6) |
+| `GUNICORN_HOST` | Bind host | `[::]` |
+| `GUNICORN_PORT` | Bind port | `8000` |
+| `GUNICORN_WORKERS` | Number of workers | Number of CPUs |
+| `GUNICORN_ARGS` | Additional arguments | (none) |
+
+### With Configuration
+
+```bash
+docker run -p 9000:9000 -v $(pwd):/app \
+  -e GUNICORN_PORT=9000 \
+  -e GUNICORN_WORKERS=4 \
+  -e GUNICORN_ARGS="--timeout 120 --access-logfile -" \
+  ghcr.io/benoitc/gunicorn app:app
+```
+
+### As Base Image (Recommended for Production)
+
+```dockerfile
+FROM ghcr.io/benoitc/gunicorn:24.1.0
+
+# Install app dependencies
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy application
+COPY --chown=gunicorn:gunicorn . .
+
+CMD ["myapp:app", "--workers", "4"]
+```
+
+### With Docker Compose
+
+```yaml
+services:
+  web:
+    image: ghcr.io/benoitc/gunicorn:latest
+    ports:
+      - "8000:8000"
+    volumes:
+      - ./app:/app
+    command: ["myapp:app", "--workers", "4"]
+```
+
+### Available Tags
+
+- `ghcr.io/benoitc/gunicorn:latest` - Latest release
+- `ghcr.io/benoitc/gunicorn:24.1.0` - Specific version
+- `ghcr.io/benoitc/gunicorn:24.1` - Minor version
+- `ghcr.io/benoitc/gunicorn:24` - Major version
+
+## Building Your Own Image
+
+For more control, build a custom image using the patterns below.
+
 ## Basic Dockerfile
 
 ```dockerfile

docs/content/install.md

@@ -20,8 +20,8 @@
 === "Docker"
 
     ```bash
-    docker run -p 8000:8000 -v $(pwd):/app -w /app \
-        python:3.12-slim sh -c "pip install gunicorn && gunicorn app:app"
+    docker pull ghcr.io/benoitc/gunicorn:latest
+    docker run -p 8000:8000 -v $(pwd):/app ghcr.io/benoitc/gunicorn app:app
     ```
 
     See the [Docker guide](guides/docker.md) for production configurations.