wireguard-go/dev-setup.md

# WireGuard Go Development Environment

This repository includes a comprehensive Nix flake development environment with all the tools needed for efficient Go development.

## 🚀 Quick Start

### Prerequisites
- [Nix](https://nixos.org/download.html) with flakes enabled
- [direnv](https://direnv.net/) (optional but recommended)

### Setup

1. **Clone and enter the repository:**
   ```bash
   git clone <repo-url>
   cd wireguard-go
   ```

2. **Option A: Using direnv (Recommended)**
   ```bash
   direnv allow
   ```
   This will automatically load the development environment when you enter the directory.

3. **Option B: Manual activation**
   ```bash
   nix develop
   ```

## 🔧 Included Tools

### Core Go Tools
- **Go 1.23.1** - Matching the project's go.mod
- **gopls** - Official Go Language Server for LSP support

### Code Quality
- **golangci-lint** - Comprehensive linter with 30+ linters enabled
- **staticcheck** - Advanced static analysis
- **gosec** - Security vulnerability scanner
- **govulncheck** - Official Go vulnerability scanner
- **gofumpt** - Stricter version of gofmt

### Development Tools
- **delve** - Go debugger
- **air** - Live reload for development
- **gotests** - Automatic test generation
- **gomodifytags** - Struct tag manipulation
- **impl** - Interface implementation generator
- **gotestsum** - Enhanced test output

### System Tools
- **wireguard-tools** - WireGuard utilities
- **iproute2** - Network configuration tools
- **iptables** - Firewall utilities

## 🎯 Quick Commands

### Development Workflow
```bash
# Install/update dependencies
go mod tidy

# Run comprehensive linting
golangci-lint run

# Check for security vulnerabilities
govulncheck ./...

# Run tests with coverage
go test -race -coverprofile=coverage.out ./...

# Generate tests for a package
gotests -all -w ./device

# Start live reload development server
air

# Format code with stricter rules
gofumpt -w .
```

### Building and Testing
```bash
# Build the project
go build .

# Run all tests
go test ./...

# Run tests with race detection
go test -race ./...

# Benchmark tests
go test -bench=. ./...

# Generate coverage report
go test -coverprofile=coverage.out ./... && go tool cover -html=coverage.out
```

### Debugging
```bash
# Start delve debugger
dlv debug

# Debug a specific test
dlv test ./device
```

## 📝 Editor Integration

### VS Code
A `.vscode/settings.json` is included with optimized settings for Go development:
- Automatic formatting with gofumpt
- Integrated linting with golangci-lint
- Proper LSP configuration
- Optimized file watching and exclusions

### Other Editors
For vim/neovim, emacs, or other editors that support LSP:
- Use `gopls` as the language server
- Point formatters to use `gofumpt` instead of `gofmt`
- Configure linting to use `golangci-lint`

## 🔍 Code Quality Configuration

### Linting
The included `.golangci.yml` enables 30+ linters with sensible defaults:
- Security checks (gosec, G-prefixed rules)
- Performance optimizations (prealloc, ineffassign)
- Style consistency (gofumpt, goimports)
- Bug prevention (errcheck, staticcheck)

### Pre-commit Hooks (Optional)
Consider setting up pre-commit hooks:
```bash
# Create .git/hooks/pre-commit
#!/bin/bash
set -e
golangci-lint run
go test ./...
govulncheck ./...
```

## 🌍 Environment Variables

The flake automatically sets up:
- `GOPATH="$PWD/.go"`
- `GOBIN="$PWD/.go/bin"`
- `GOCACHE="$PWD/.gocache"`
- `GO111MODULE=on`
- `CGO_ENABLED=1`
- `WG_COLOR_MODE=always`

## 🧪 Testing

### Running Tests
```bash
# All tests
go test ./...

# With race detection
go test -race ./...

# Verbose output
go test -v ./...

# Specific package
go test ./device

# With coverage
go test -coverprofile=coverage.out ./...
```

### Test Generation
```bash
# Generate tests for all functions in a package
gotests -all -w ./device

# Generate tests for specific functions
gotests -only FunctionName -w ./device
```

## 🔒 Security

### Vulnerability Scanning
```bash
# Scan for known vulnerabilities
govulncheck ./...

# Security-focused linting
gosec ./...
```

### WireGuard-Specific Security
The environment includes networking tools for testing:
- WireGuard tools for protocol testing
- Network namespace utilities
- Traffic analysis tools

## 📦 Building Packages

### Development Build
```bash
go build .
```

### Optimized Build
```bash
go build -ldflags="-w -s" .
```

### Using Nix to Build
```bash
# Build using the included Nix package
nix build

# The binary will be in ./result/bin/
```

## 🐛 Troubleshooting

### Common Issues

1. **"command not found" errors**
   - Ensure you're in the flake environment: `nix develop`
   - Or allow direnv: `direnv allow`

2. **Go module issues**
   - Clean module cache: `go clean -modcache`
   - Verify modules: `go mod verify`

3. **LSP not working**
   - Restart your editor
   - Check gopls is available: `which gopls`
   - Verify Go version: `go version`

### Performance Tips
- Use `.gocache` for faster builds (already configured)
- Exclude build artifacts from file watchers
- Use `gotestsum` for faster test feedback

## 📚 Additional Resources

- [Go Documentation](https://golang.org/doc/)
- [WireGuard Protocol](https://www.wireguard.com/protocol/)
- [golangci-lint Documentation](https://golangci-lint.run/)
- [Delve Debugger](https://github.com/go-delve/delve)