mcp-vosdroits: Instructions file for GitHub Copilot

Docker Guidelines

Multi-Stage Builds

Use multi-stage builds to create minimal production images:

1. Build stage: Compile the Go binary with all dependencies
2. Production stage: Copy only the binary to a minimal base image

Go-Specific Best Practices

Static Compilation

Build statically-linked binaries for minimal images:

CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o app .

Base Images

• Use golang:1.23-alpine for build stage (smaller than full golang image)
• Use scratch or alpine for production stage
• For scratch images, ensure binary is statically linked
• For alpine, include necessary CA certificates

Binary Optimization

• Use -ldflags="-w -s" to strip debug information and reduce binary size
• Consider using UPX for further compression (if acceptable)

Security

User Permissions

• Don't run as root in production
• Create a non-root user in the image
• Use USER directive to switch to non-root user

Image Scanning

• Regularly scan images for vulnerabilities
• Keep base images updated
• Minimize the number of layers

Secrets Management

• Never hardcode secrets in Dockerfile
• Use build arguments for build-time secrets
• Use environment variables or secret management for runtime secrets
• Don't commit sensitive files

Image Optimization

Layer Caching

• Order commands from least to most frequently changing
• Copy go.mod and go.sum first, then download dependencies
• Copy source code last

Size Reduction

• Remove unnecessary files
• Use .dockerignore to exclude files from build context
• Combine RUN commands to reduce layers
• Clean up package manager caches

Health Checks

• Add HEALTHCHECK instruction for container health monitoring
• Keep health checks lightweight
• Set appropriate timeout and interval

Labels

• Use LABEL instructions for metadata
• Include version, description, maintainer
• Follow OCI image spec annotations

Example Structure