gh-vanman2024-cli-builder-plugins-cli-builder/skills/cli-patterns/examples/EXAMPLES-INDEX.md

CLI Patterns Examples Index

Comprehensive examples demonstrating urfave/cli patterns in production-ready applications.

Example Applications

1. Database CLI Tool (db-cli/)

Purpose: Complete database management CLI with categories, hooks, and connection handling.

Features:

• Command categories (Schema, Data, Admin)
• Before hook for connection validation
• After hook for cleanup
• Required and optional flags
• Environment variable fallbacks

Commands:

• migrate - Run migrations with direction and steps
• rollback - Rollback last migration
• seed - Seed database with test data
• backup - Create database backup
• restore - Restore from backup
• status - Check database status
• vacuum - Optimize database

Key Patterns:

// Connection validation in Before hook
Before: func(c *cli.Context) error {
    conn := c.String("connection")
    // Validate connection
    return nil
}

// Cleanup in After hook
After: func(c *cli.Context) error {
    // Close connections
    return nil
}

---

2. Deployment CLI Tool (deploy-cli/)

Purpose: Deployment automation with context management and environment validation.

Features:

• Context management with shared state
• Environment validation
• Confirmation prompts for destructive actions
• AWS region configuration
• Build, deploy, and monitor workflows

Commands:

• build - Build application with tags
• test - Run test suite
• deploy - Deploy to environment (with confirmation)
• rollback - Rollback to previous version
• logs - View deployment logs
• status - Check deployment status

Key Patterns:

// Shared context across commands
type DeployContext struct {
    Environment string
    AWSRegion   string
    Verbose     bool
}

// Store context in Before hook
ctx := &DeployContext{...}
c.App.Metadata["ctx"] = ctx

// Retrieve in command
ctx := c.App.Metadata["ctx"].(*DeployContext)

---

3. API Client CLI Tool (api-cli/)

Purpose: REST API client with HTTP client sharing and authentication.

Features:

• HTTP client sharing via context
• Authentication in Before hook
• Multiple HTTP methods (GET, POST, PUT, DELETE)
• Request timeout configuration
• Token masking for security

Commands:

• get - GET request with headers
• post - POST request with data
• put - PUT request with data
• delete - DELETE request
• auth-test - Test authentication

Key Patterns:

// HTTP client in context
type APIContext struct {
    BaseURL    string
    Token      string
    HTTPClient *http.Client
}

// Initialize in Before hook
client := &http.Client{Timeout: timeout}
ctx := &APIContext{
    HTTPClient: client,
    ...
}

// Use in commands
ctx := c.App.Metadata["ctx"].(*APIContext)
resp, err := ctx.HTTPClient.Get(url)

---

Pattern Summary

Context Management

All three examples demonstrate different context patterns:

• db-cli: Connection validation and cleanup
• deploy-cli: Shared deployment configuration
• api-cli: HTTP client and authentication sharing

Before/After Hooks

• Before: Setup, validation, authentication, connection establishment
• After: Cleanup, resource release, connection closing

Command Categories

Organized command groups for better UX:

• db-cli: Schema, Data, Admin
• deploy-cli: Build, Deploy, Monitor
• api-cli: No categories (simple HTTP verbs)

Flag Patterns

• Required flags: --connection, --env, --token
• Environment variables: All support env var fallbacks
• Aliases: Short forms (-v, -e, -t)
• Multiple values: StringSlice for headers
• Custom types: Duration for timeouts

Error Handling

All examples demonstrate:

• Validation in Before hooks
• Proper error returns
• User-friendly error messages
• Exit code handling

Running the Examples

Database CLI

export DATABASE_URL="postgres://user:pass@localhost/mydb"
cd examples/db-cli
go build -o dbctl .
./dbctl migrate
./dbctl backup --output backup.sql

Deployment CLI

export DEPLOY_ENV=staging
export AWS_REGION=us-east-1
cd examples/deploy-cli
go build -o deploy .
./deploy build --tag v1.0.0
./deploy deploy

API Client CLI

export API_URL=https://api.example.com
export API_TOKEN=your_token_here
cd examples/api-cli
go build -o api .
./api get /users
./api post /users '{"name":"John"}'

Learning Path

Beginner:

1. Start with db-cli - demonstrates basic categories and hooks
2. Study Before/After hook patterns
3. Learn flag types and validation

Intermediate: 4. Study deploy-cli - context management and shared state 5. Learn environment validation 6. Understand confirmation prompts

Advanced: 7. Study api-cli - HTTP client sharing and authentication 8. Learn complex context patterns 9. Understand resource lifecycle management

Cross-Language Comparison

Each example can be implemented in other languages:

• TypeScript: Use commander.js (see templates/)
• Python: Use click or typer (see templates/)
• Ruby: Use thor
• Rust: Use clap

The patterns translate directly across languages with similar CLI frameworks.