gotell

Golang OTEL library, an opinionated thin-wrapper over the OpenTelemetry SDK

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📝 Table of Contents

• About
• Getting Started
• Usage
• Built Using
• TODO
• Contributing
• Authors
• Acknowledgments

🧐 About

Gotell is an opinionated thin wrapper on top of the OpenTelemetry Go SDK. It applies semantic convention metrics and attributes for you so you don't have to.

The name gotell comes from go + otel (OpenTelemetry) + library. 😉

🏁 Getting Started

Run go get github.com/wwmoraes/gotell or add the repository to your imports then run go mod tidy.

🔧 Running the tests

Run task test 😄

🎈 Usage

package main

import (
  "context"
  "errors"
  "fmt"
  "net"
  "net/http"
  "os"
  "os/signal"
  "time"

  telemetry "github.com/wwmoraes/gotell"
  "go.opentelemetry.io/otel/attribute"
  "go.opentelemetry.io/otel/sdk/resource"
)

const (
  NAMESPACE = "github.com/wwmoraes/gotell"
  NAME      = "http-server"
)

var version = "0.0.0"

func main() {
  ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
  defer cancel()

  hostname, err := os.Hostname()
  if err != nil {
    fmt.Fprintln(os.Stderr, err)
    os.Exit(1)
  }

  err = telemetry.Initialize(ctx, resource.NewSchemaless(
    attribute.String("service.name", NAME),
    attribute.String("service.namespace", NAMESPACE),
    attribute.String("service.version", version),
    attribute.String("host.id", hostname),
  ))
  if err != nil {
    fmt.Fprintln(os.Stderr, err)
    os.Exit(1)
  }

  log := telemetry.Logr(ctx)

  mux := http.NewServeMux()

  mux.Handle("/", telemetry.WithInstrumentationMiddleware(http.HandlerFunc(helloHandler)))

  listener, err := net.Listen("tcp4", "127.0.0.1:0")
  if !errors.Is(err, http.ErrServerClosed) {
    log.Error(err, "failed to create listener")
    os.Exit(1)
  }

  server := http.Server{
    Handler:           mux,
    ReadTimeout:       time.Minute / 2,
    ReadHeaderTimeout: time.Minute / 2,
  }

  log.Info("serving HTTP", "address", listener.Addr().String())

  err = server.Serve(listener)
  if !errors.Is(err, http.ErrServerClosed) {
    log.Error(err, "server stopped")
  }
}

func helloHandler(w http.ResponseWriter, r *http.Request) {
  ctx, span := telemetry.Start(r.Context())
  defer span.End()

  log := telemetry.Logr(ctx)

  log.Info("hello handler triggered")

  name := r.URL.Query().Get("name")
  if name == "" {
    name = "stranger"
  }

  span.SetAttributes(attribute.String("name", name))

  fmt.Fprintf(w, "hello %s!", name)
}

🔧 Built Using

• OpenTelemetry Go SDK - Core telemetry engine
• Go - Programming language

🧑‍💻 Authors

• @wwmoraes - Idea & Initial work

🎉 Acknowledgements

• OpenTelemetry https://opentelemetry.io