go-otelroundtripper

This package provides an easy way to collect http related metrics (e.g Response times, Status Codes, number of in flight requests etc) for your HTTP API Clients. You can do this by using this round tripper when instantiating the http.Client{}.

Why this package exists

I currently have to integrate with multiple APIs and I needed a simple way to export metrics for those external API's. Sometimes external API's have their own SDK and the only input is http.Client. In this scenario, I can create an HTTP client with a round tripper automatically exports metrics according to the open telemetry specification.

Installation

go-otelroundtripper is compatible with modern Go releases in module mode, with Go installed:

go get github.com/NdoleStudio/go-otelroundtripper

Alternatively the same can be achieved if you use import in a package:

import "github.com/NdoleStudio/go-otelroundtripper"

Usage

This is a sample code that instantiates an HTTP client which sends requests to https://example.com. You can see a runnable example here

client := http.Client{
    Transport: New(
        WithName("example.com"),
        WithMeter(global.MeterProvider()Meter("otel-round-tripper")),
        WithAttributes(
            semconv.ServiceNameKey.String("otel-round-tripper"),
        ),
    ),
}

response, err := client.Get("https://example.com")

Metrics Emitted

The following metrics will be emitted by this package. Note that * will be replaced by the prefix passed in WithName().

• *.no_request http calls with nil http.Request
• *.errors http requests which had an error response i.e err != nil
• *.success http requests which were successfull. Meaning there were no transport errors
• *.timeouts http requests which timed out
• *.cancelled http requests with cancelled context
• *.deadline_exceeded http requests with context dateline exceeded
• *.total_duration total time it takes to execute the http request in milliseconds
• *.in_flight concurrent http requests
• *.attempts http requests attempted
• *.failures http requests with http status code >= 400
• *.redirects http requests with 300 <= http status code < 400

Testing

You can run the unit tests for this client from the root directory using the command below:

go test -v

License

This project is licensed under the MIT License - see the LICENSE file for details