go-http-server-with-otel/main.go

// This template contains a simple
// app with OTEL bootstrap that will create an
// HTTP server configured by environment that exports
// spans and metrics to an OTEL collector if configured
// to do so. Will also stand up a prometheus metrics
// endpoint.
//
// Configuration and logger stored in context
package main

import (
	"context"
	"os"
	"os/signal"
	"time"

	"github.com/rs/zerolog"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/codes"
	"golang.org/x/sys/unix"

	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/config"
	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/logging"
	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/observability"
)

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

	// Set up app config and logging
	ctx, err := config.LoadConfig(ctx)
	if err != nil {
		panic(err)
	}

	cfg := config.MustFromCtx(ctx)
	ctx = logging.MustInitLogging(ctx)
	l := zerolog.Ctx(ctx)

	// Set up OTEL
	opts := make([]observability.Option, 0)
	if cfg.Logging.Level == "trace" {
		opts = append(opts, observability.EnableStdoutExporter)
	}
	shutdown := observability.Init(ctx, opts...)
	defer func() {
		shutdownCtx, cncl := context.WithTimeout(context.Background(), 30*time.Second)
		defer cncl()
		shutdown(shutdownCtx)
	}()

	// Begin Server init
	tracer := otel.Tracer(cfg.Name)
	_, initSpan := tracer.Start(ctx, "init")

	// TODO: HTTP Server

	// App Ready
	l.Trace().Any("config", *cfg).Send()
	l.Info().
		Str("name", cfg.Name).
		Str("version", cfg.Version).
		Str("logLevel", cfg.Logging.Level).
		Msg("app initialized")

	initSpan.SetStatus(codes.Ok, "")
	initSpan.End()

	<-ctx.Done()
}

func init() {}