justinrixx / retryhttp

Add HTTP retries with zero refactoring

retryhttp

retryhttp allows you to add HTTP retries to your service or application with no refactoring at all, just a few lines of configuration where your client is instantiated. This package's goals are:

• Make adding retries easy, with no refactor required (as stated above)
• Provide a good starting point for retry behavior
• Make customizing retry behavior easy
• Allow for one-off behavior changes without needing multiple HTTP clients
• 100% standard library, with no external dependencies (have a peek at go.mod)

How it works

retryhttp exports a Transport struct which implements the standard library's http.RoundTripper interface. By performing retries at the http.RoundTripper level, retries can be introduced to a service or script with just a few lines of configuration and no changes required to any of the code actually making HTTP requests. Regardless of which HTTP client you're using, it's very likely to have a configurable http.RoundTripper, which means this package can be integrated.

http.RoundTrippers are also highly composable. By default, this package uses http.DefaultTransport as its underlying RoundTripper, but you may choose to wrap a customized one that sets MaxIdleConns, or even something like this that captures metric spans to instrument your calls.

Get it

$ go get github.com/justinrixx/retryhttp

Example

// BEFORE
client := http.Client{
    // HTTP client options
}

// AFTER
client := http.Client{
    Transport: retryhttp.New(
        // optional retry configurations
        retryhttp.WithShouldRetryFn(func(attempt retryhttp.Attempt) bool {
            return attempt.Res != nil && attempt.Res.StatusCode == http.StatusServiceUnavailable
        }),
        retryhttp.WithDelayFn(func(attempt retryhttp.Attempt) time.Duration {
            return expBackoff(attempt.Count)
        }),
        retryhttp.WithMaxRetries(2),
    ),
    // other HTTP client options
}

This package was inspired by https://github.com/PuerkitoBio/rehttp/ but it aims to take away a couple footguns, provide widely-applicable defaults, and make one-off overriding options easy using context keys.

License

MIT