Wait4X as an Importable Package

These examples demonstrate how to use Wait4X as an importable package in your Go applications. Wait4X isn't just a CLI tool - it provides a powerful library that you can integrate directly into your Go code.

Examples Overview

1. Basic TCP Checker (tcp_basic/main.go): Simple example of waiting for a TCP port to become available.

2. Advanced HTTP Checker (http_advanced/main.go): Demonstrates complex HTTP checking with custom headers, body validations, status code checks, and more.

3. Parallel Service Checking (parallel_services/main.go): Shows how to check multiple services in parallel, waiting for all of them to be ready before proceeding.

4. Reverse Checking (reverse_checking/main.go): Example of using the inverse check to wait for a port to become free.

5. Custom Checker (custom_checker/main.go): Shows how to create your own custom checker by implementing the Checker interface.

Using Wait4X in Your Go Projects

To use Wait4X in your Go project, add it as a dependency:

go get wait4x.dev/v3

Then import the packages you need:

import (
    "wait4x.dev/v3/checker/tcp"      // TCP checker
    "wait4x.dev/v3/checker/http"     // HTTP checker
    "wait4x.dev/v3/checker/redis"    // Redis checker
    // ...other checkers
    "wait4x.dev/v3/waiter"           // Waiter functionality
)

Core Components

1. Checkers: Implements the checker.Checker interface:

   type Checker interface {
       Identity() (string, error)
       Check(ctx context.Context) error
   }

2. Waiter: Provides waiting functionality with options like timeout, interval, backoff, etc.

3. Context Usage: All checkers and waiters support context for cancellation and timeouts.

Common Patterns

1. Option Pattern: All checkers use the functional options pattern for configuration.

2. Error Handling: Use the ExpectedError type for expected failures vs. unexpected errors.

3. Parallel Execution: Use WaitParallelContext to check multiple services simultaneously.

4. Context Propagation: Always pass context to allow for proper cancellation and timeouts.

Extending Wait4X

To create your own checker:

1. Define a type that implements the checker.Checker interface
2. Implement the Identity() and Check() methods
3. Use the checker.NewExpectedError() function for creating appropriate error types

See custom_checker.go for a complete example of implementing a custom checker.

Best Practices

1. Always use contexts with timeouts to prevent indefinite waiting
2. Consider using exponential backoff for services that might take a while to start
3. Use parallel checking when waiting for multiple independent services
4. Handle errors appropriately - distinguish between timeout errors and other errors
5. Add logging where appropriate to understand what's happening during waiting

Additional Resources

• Go Reference Documentation: https://pkg.go.dev/wait4x.dev/v3
• GitHub Repository: https://github.com/wait4x/wait4x
• Report Issues: https://github.com/wait4x/wait4x/issues