go-otel-gorm

OpenTelemetry Package for the Gorm ORM

This package is meant to simplify wrapping Gorm requests to databases with OpenTelemetry Tracing Spans. The functionality within the package is as of OpenTelemetry-go v0.2.1 and is subject to change fairly rapidly as the standard is evolved.

This package is B.Y.O.E. (Bring Your Own Exporter)

Metrics support coming soon!

Example Usage

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"time"

	"github.com/jdefrank/go-otel-gorm/otgorm"

	"github.com/go-chi/chi"
	"github.com/jinzhu/gorm"
	_ "github.com/joho/godotenv/autoload"
	"go.opentelemetry.io/otel/api/global"
	"go.opentelemetry.io/otel/exporter/trace/jaeger"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

type user struct {
	ID        uint      `gorm:"primary_key" json:"id"`
	FirstName string    `json:"firstName"`
	LastiName string    `json:"lastName"`
	CreatedAt time.Time `json:"createdAt"`
	UpdatedAt time.Time `json:"updatedAt"`
}

func readBody(bodyreader io.ReadCloser) (data []byte, err error) {
	body, err := ioutil.ReadAll(io.LimitReader(bodyreader, 1048576))
	if err != nil {
		return nil, err
	}
	if err := bodyreader.Close(); err != nil {
		return nil, err
	}
	return body, nil
}

// NOTE: I've found that if you'd like to separate services in the Jaeger UI,
// you'll need to create multiple exporters which in turn will show you different colors
// per service.
func initTracer() func() {
	//Create Jaeger exporter
	exporter, err := jaeger.NewExporter(
		jaeger.WithCollectorEndpoint(fmt.Sprintf("https://%s/api/traces", os.Getenv("JAEGER_HOST"))),
		jaeger.WithProcess(jaeger.Process{
			ServiceName: "go-otel-gorm",
		}),
	)
	if err != nil {
		log.Fatal(err)
	}
	// For demoing purposes, always sample. In a production application, you should
	// configure this to a trace.ProbabilitySampler set at the desired
	// probability.
	tp, err := sdktrace.NewProvider(
		sdktrace.WithConfig(sdktrace.Config{DefaultSampler: sdktrace.AlwaysSample()}),
		sdktrace.WithSyncer(exporter))
	if err != nil {
		log.Fatal(err)
	}
	global.SetTraceProvider(tp)
	return func() {
		exporter.Flush()
	}
}

func main() {
	//Setup the exporter and defer close until main exits
	fn := initTracer()
	defer fn()

	// Connect to database
	dsn := fmt.Sprintf(
		"%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True",
		os.Getenv("DB_USER"),
		os.Getenv("DB_PASS"),
		os.Getenv("DB_HOST"),
		os.Getenv("DB_PORT"),
		os.Getenv("DB_NAME"),
	)
	db, err := gorm.Open("mysql", dsn)
	if err != nil {
		panic(err)
	}

	//Register callbacks for GORM, while also passing in config Opts
	otgorm.RegisterCallbacks(db, global.TraceProvider().Tracer("component-gorm"), otgorm.Query(true))

	//Run migration and create a record
	db.AutoMigrate(user{})
	newUser := user{
		FirstName: "John",
		LastiName: "Smith",
	}
	err = db.Create(&newUser).Error
	if err != nil {
		log.Print(err)
	}

	//Create router
	r := chi.NewRouter()

	//Register Endpoints for the API
	r.Post("/user", func(w http.ResponseWriter, r *http.Request) {
		orm := otgorm.WithContext(r.Context(), db)
		var u user
		body, err := readBody(r.Body)
		if err != nil {
			log.Print(err)
			return
		}
		err = json.Unmarshal(body, &u)
		if err != nil {
			log.Print(err)
			return
		}
		err = orm.Create(&u).Error
		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			json.NewEncoder(w).Encode("{\"Error\":\"" + err.Error() + "\"")
			return
		}
		w.WriteHeader(http.StatusOK)
		return
	})
	http.ListenAndServe(":3000", r)
}

License

The MIT License (MIT). Please see License File for more information.