Go-resty OpenTelemetry Instrumentation

This repository aims to create a custom instrumentation for the go-resty project.

Requirements

Go 1.26.0 or newer, matching the minimum version required by OpenTelemetry Go SDK v1.47.0.

How to use

Usage is as simple as calling TraceClient passing a resty client and options, if needed.

TraceClient uses the OnBeforeRequest, OnAfterResponse and OnError hooks from the resty client to create spans and fill their attributes with request, response and error information.

Note that resty hooks follow a queue order, meaning the first hook hook added will run before the others, so make sure to call TraceClient after adding your custom hooks so that the span information will have the correct values (considering your hooks modify request/response information).

func main() {
  cli := resty.New()
  opts := []otelresty.Option{otelresty.WithTracerName("my-tracer")}

  otelresty.TraceClient(cli, opts...)
}

Retries

Each retry attempt gets its own span, chained to the previous attempt's span as its parent, and every attempt span is properly ended. If all attempts fail, the error is recorded on the last attempt's span.

Ignoring errors

Some resty errors are not real failures for your use case. For example, with resty.NoRedirectPolicy, every redirected request returns resty.ErrAutoRedirectDisabled and would otherwise end up in a span with an error status.

Use WithIgnoredErrors to pass a list of errors (matched with errors.Is, so sentinel and wrapped errors work):

otelresty.TraceClient(cli, otelresty.WithIgnoredErrors(resty.ErrAutoRedirectDisabled))

For more control, WithErrorIgnorer takes a predicate consulted before the span is marked as erroneous:

otelresty.TraceClient(cli, otelresty.WithErrorIgnorer(func(err error) bool {
  // return true to leave the span status untouched
  return false
}))

Resty v3

Clients from resty v3 (resty.dev/v3) are supported by the restyv3 package, which is part of the same module:

import (
  "resty.dev/v3"

  "github.com/dubonzi/otelresty/restyv3"
)

func main() {
  cli := resty.New()

  restyv3.TraceClient(cli, restyv3.WithTracerName("my-tracer"))
}

It supports the same options as the resty v2 package, including WithErrorIgnorer and WithIgnoredErrors, which keep matching errors (checked with errors.Is) from marking the span as failed:

restyv3.TraceClient(cli, restyv3.WithIgnoredErrors(errRedirectDisabled))

A span is created for each request attempt. When a request is retried, each attempt gets its own span, chained as a child of the previous attempt's span, and every span is ended exactly once. Spans use the OpenTelemetry HTTP semantic conventions (semconv/v1.37.0).

Configure the transport, proxy, redirect policy and response middleware before calling restyv3.TraceClient. It wraps the configured transport and redirect policy, and captures response middleware errors before resty v3 rc.4 clears errors during retry processing. Replacing those components afterward bypasses error capture. URL credentials are redacted in both resty.url and url.full.

Retry spans are finalized when the next attempt starts, using an end timestamp from before the backoff wait. If cancellation or the retry strategy stops the request during backoff, the final hook records that error and ends the current span instead.