fix(docker): multi-stage build and publish tags

- Split Dockerfile into builder and runtime stages
- Put .venv on PATH so pymodbus resolves in the container
- Push image to Docker Hub and GHCR with latest and 7-char SHA tags
- Use real repo/image names in README

.github/workflows/docker-publish.yml

@@ -1,4 +1,4 @@
-name: Build and Push to Docker Hub
+name: Build and Push Docker Image
 
 on:
   push:
@@ -9,9 +9,12 @@ on:
     branches: [main]
 
 env:
-  REGISTRY: docker.io
   IMAGE_NAME: ${{ secrets.DOCKERHUB_USERNAME }}/modbus-slave
 
+permissions:
+  contents: read
+  packages: write
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -30,17 +33,27 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Login to GitHub Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Extract metadata
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ${{ env.IMAGE_NAME }}
+          images: |
+            ${{ env.IMAGE_NAME }}
+            ghcr.io/${{ github.repository }}
           tags: |
-            type=ref,event=branch
+            type=raw,value=latest,enable={{is_default_branch}}
+            type=sha,prefix=
             type=ref,event=pr
             type=semver,pattern={{version}}
             type=semver,pattern={{major}}.{{minor}}
-            type=sha,prefix=
 
       - name: Build and push
         uses: docker/build-push-action@v6

Dockerfile

@@ -1,10 +1,18 @@
-FROM python:3.11-slim
+# Stage 1: build and install dependencies
+FROM python:3.11-slim AS builder
 
 WORKDIR /app
 
-# Install dependencies
 COPY pyproject.toml uv.lock ./
-RUN pip install uv && uv sync --frozen
+RUN pip install --no-cache-dir uv && uv sync --frozen --no-dev --no-install-project
+
+# Stage 2: runtime (slim, no build toolchain)
+FROM python:3.11-slim AS runtime
+
+WORKDIR /app
+
+COPY --from=builder /app/.venv ./.venv
+ENV PATH="/app/.venv/bin:$PATH"
 
 # Copy application
 COPY main.py ./

README.md

@@ -15,7 +15,7 @@ A configurable Modbus slave simulator for testing Modbus TCP, RTU, and TLS conne
 ### From Source
 
 ```bash
-git clone <repository-url>
+git clone https://github.com/zihluwang/modbus-slave
 cd modbus-slave
 pip install -r requirements.txt
 ```
@@ -23,7 +23,7 @@ pip install -r requirements.txt
 ### With Docker
 
 ```bash
-docker pull <username>/modbus-slave
+docker pull zihluwang/modbus-slave
 ```
 
 ## Usage
@@ -51,10 +51,10 @@ python main.py --holding-registers-default 100 --coils-default true
 
 ```bash
 # Run with defaults
-docker run -p 5020:5020 <username>/modbus-slave
+docker run -p 5020:5020 zihluwang/modbus-slave
 
 # Run with custom arguments
-docker run -p 5020:5020 <username>/modbus-slave --holding-registers-size 1000
+docker run -p 5020:5020 zihluwang/modbus-slave --holding-registers-size 1000
 ```
 
 ## Command Line Options