Add CI/CD workflow for automated Docker image build and publish

Author: zuedev

.github/workflows/docker-publish.yml

@@ -0,0 +1,59 @@
+name: Build and Publish Docker Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "v*"
+  pull_request:
+    branches:
+      - main
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=sha
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

README.md

@@ -205,6 +205,44 @@ View all available arguments:
 java -jar HytaleServer.jar --help
 ```
 
+## Development
+
+### Building Locally
+
+```bash
+docker build -t hytale-server .
+```
+
+### CI/CD
+
+This project uses GitHub Actions to automatically build and publish the Docker image to GitHub Container Registry (ghcr.io).
+
+**Triggers:**
+
+- Push to `main` branch
+- Version tags (`v*`)
+- Pull requests (build only, no push)
+
+**Image Tags:**
+
+| Trigger        | Example Tags                       |
+| -------------- | ---------------------------------- |
+| Push to `main` | `main`, `sha-abc1234`              |
+| Tag `v1.2.3`   | `1.2.3`, `1.2`, `1`, `sha-abc1234` |
+
+**Publishing a Release:**
+
+```bash
+git tag v1.0.0
+git push origin v1.0.0
+```
+
+The image will be available at:
+
+```
+ghcr.io/<username>/hytale-server-docker:latest
+```
+
 ## Resources
 
 - [Official Hytale Server Manual](https://support.hytale.com/hc/en-us/articles/45326769420827-Hytale-Server-Manual)