Add Docker support for MCP server

[apetti1920]

Summary

Add Docker support for building and running the Chronosphere MCP server in streamable HTTP mode with automated CI/CD integration.

Changes

• Dockerfile: Generic multi-stage build with version injection support
• GitHub Actions CI: Docker build testing and automated publishing workflow
• README Documentation: Docker build and run instructions

Docker Features

• Multi-stage build: Optimized image size with separate build and runtime stages
• Security: Non-root user execution (UID 1001)
• Version injection: Build args for VERSION, GIT_COMMIT, and BUILD_DATE
• Health checks: Process monitoring with 30s intervals
• Configuration: Volume-mountable config files for custom setups
• HTTP transport: Streamable MCP mode on port 8081 by default

CI/CD Integration

docker-build Job (All Runs)

• Runs on all PRs and pushes
• Tests Docker image builds without publishing
• Uses GitHub Actions cache for performance
• Validates Dockerfile on every change

docker-push Job (Main Branch & Tags)

• Publishes to GitHub Container Registry (ghcr.io)
• Conditional: Only runs on main branch merges and version tags
• Depends on all tests passing: [build, golangci, test, docker-build]
• Automatic authentication via GITHUB_TOKEN

Image Tags Strategy

Version Tag (e.g., v0.3.5):

• ghcr.io/chronosphereio/chronosphere-mcp:v0.3.5
• ghcr.io/chronosphereio/chronosphere-mcp:0.3.5
• ghcr.io/chronosphereio/chronosphere-mcp:0.3
• ghcr.io/chronosphereio/chronosphere-mcp:<commit-sha>
• ghcr.io/chronosphereio/chronosphere-mcp:latest

Main Branch Push:

• ghcr.io/chronosphereio/chronosphere-mcp:<commit-sha>
• ghcr.io/chronosphereio/chronosphere-mcp:latest

Usage

Build Locally

docker build \
  --build-arg VERSION=$(git describe --tags --always --dirty) \
  --build-arg GIT_COMMIT=$(git rev-parse HEAD) \
  --build-arg BUILD_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ) \
  -t chronomcp:latest .

Run Container

docker run -p 8081:8081 \
  -e CHRONOSPHERE_ORG_NAME=<your-org> \
  -e CHRONOSPHERE_API_TOKEN=<your-token> \
  chronomcp:latest

Custom Configuration

docker run -p 8081:8081 \
  -v $(pwd)/custom-config.yaml:/app/config.yaml \
  -e CHRONOSPHERE_ORG_NAME=<your-org> \
  -e CHRONOSPHERE_API_TOKEN=<your-token> \
  chronomcp:latest

Pull from GHCR (After Merge)

docker pull ghcr.io/chronosphereio/chronosphere-mcp:latest

Testing

Tested with:
- Docker build completes successfully
- Binary runs and serves MCP on port 8081
- Health check validates process running
- Config file mounting works correctly
- Non-root user execution verified

Notes

- Based on existing project patterns and Go 1.23.4 requirements
- Compatible with MCP inspector debugging workflow
- No breaking changes to existing build/run processes