Various fixes for issue #8 (#9)

- added caution for Windows usage
- APM usage without initialization now panics instead of auto-init
- fixed issue with OTEL init without collector URL for traces
- some default IDE configs

Author: ph4n70m-nuk3r

.gitignore

@@ -105,3 +105,11 @@ $RECYCLE.BIN/
 *.lnk
 
 # End of https://www.toptal.com/developers/gitignore/api/go,visualstudiocode,osx,linux,windows
+
+### Additional IDEs/Editors. ###
+/.idea/
+/*.iml
+
+/.vimrc
+*.swp
+*.tmp

inits.go

@@ -27,12 +27,13 @@ var now = time.Now()
 
 func startAPM(ctx context.Context, cfg *configs.Configs) *apm.APM {
 	ap, err := apm.New(ctx, &apm.Options{
-		Debug:            cfg.Environment == configs.EnvLocal,
-		Environment:      cfg.Environment.String(),
-		ServiceName:      cfg.AppName,
-		ServiceVersion:   cfg.AppVersion,
-		TracesSampleRate: 50.00,
-		UseStdOut:        cfg.Environment == configs.EnvLocal,
+		Debug:                cfg.Environment == configs.EnvLocal,
+		Environment:          cfg.Environment.String(),
+		ServiceName:          cfg.AppName,
+		ServiceVersion:       cfg.AppVersion,
+		PrometheusScrapePort: 9090,
+		TracesSampleRate:     50.00,
+		UseStdOut:            cfg.Environment == configs.EnvLocal,
 	})
 	if err != nil {
 		panic(errors.Wrap(err, "failed to start APM"))

internal/pkg/apm/apm.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/naughtygopher/errors"
+	"github.com/naughtygopher/goapp/internal/pkg/logger"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
 	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
@@ -70,7 +71,7 @@ func New(ctx context.Context, opts *Options) (*APM, error) {
 	s.meterProvider = mProvider
 	SetGlobal(s)
 
-	return s, nil
+	return Global(), nil
 }
 
 // Shutdown gracefully switch off apm, flushing any data it have
@@ -140,9 +141,7 @@ func SetGlobal(apm *APM) {
 // Global gets global apm instance
 func Global() *APM {
 	if global == nil {
-		apm, _ := New(context.Background(), &Options{UseStdOut: false})
-		global = apm
-		return apm
+		logger.Error(context.Background(), "APM access attempt before initialisation is a bug")
 	}
 	return global
 }
@@ -187,6 +186,9 @@ func newTracer(ctx context.Context, opts *Options) (trace.TracerProvider, *Trace
 
 	if opts.UseStdOut {
 		exporter, err = stdouttrace.New()
+	} else if opts.CollectorURL == "" {
+		// Using no-op tracer as CollectorURL was not set.
+		return nil, nil, nil
 	} else if httpCollector {
 		exporter, err = otlptracehttp.New(
 			ctx,

internal/pkg/apm/prometheus.go

@@ -1,11 +1,13 @@
 package apm
 
 import (
+	"context"
 	"fmt"
 	"net/http"
 	"time"
 
 	"github.com/naughtygopher/errors"
+	"github.com/naughtygopher/goapp/internal/pkg/logger"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"go.opentelemetry.io/otel/exporters/prometheus"
 )
@@ -24,24 +26,13 @@ func prometheusScraper(opts *Options) {
 	mux.Handle("/-/metrics", promhttp.Handler())
 	server := &http.Server{
 		Handler:           mux,
-		Addr:              fmt.Sprintf("%d", opts.PrometheusScrapePort),
+		Addr:              fmt.Sprintf(":%d", opts.PrometheusScrapePort),
 		ReadHeaderTimeout: 5 * time.Second,
 	}
 
-	// logger.Info(
-	// 	"[otel/http] starting prometheus scrape endpoint",
-	// 	zap.String(
-	// 		"addr",
-	// 		fmt.Sprintf("localhost:%d/-/metrics", opts.PrometheusScrapePort),
-	// 	),
-	// )
+	logger.Info(context.Background(), fmt.Sprintf("[otel/http] starting prometheus metrics on :%d/-/metrics", opts.PrometheusScrapePort))
 	err := server.ListenAndServe()
 	if err != nil {
-		// logger.Error(
-		// 	"[otel/http] failed to serve metrics at:",
-		// 	zap.Error(err),
-		// 	zap.Uint16("port", opts.PrometheusScrapePort),
-		// )
-		return
+		logger.Error(context.Background(), fmt.Sprintf("[otel/http] failed to start prometheus metrics on :%d/-/metrics ; %+v", opts.PrometheusScrapePort, err))
 	}
 }

internal/pkg/sysignals/sysignals.go

@@ -20,6 +20,7 @@ func NotifyErrorOnQuit(errs chan<- error, otherSignals ...syscall.Signal) {
 
 	for signalType := range interrupt {
 		switch signalType {
+		// CAUTION: syscall.SIGTSTP is not supported on Windows and go build will fail.
 		case syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGTSTP:
 			errs <- errors.Wrapf(ErrSigQuit, "%v", signalType)
 			return

main.go

@@ -74,6 +74,9 @@ func main() {
 		}),
 	)
 
+	// This needs to remain after log initialisation and before server initialisation.
+	ap := startAPM(ctx, cfgs)
+
 	healthResponder, err := startHealthResponder(ctx, probestatus, fatalErr)
 	if err != nil {
 		panic(err)
@@ -93,7 +96,7 @@ func main() {
 		healthResponder,
 		hserver,
 		gserver,
-		startAPM(ctx, cfgs),
+		ap,
 	)
 	exitErr = <-fatalErr
 }

shutdown.go

@@ -38,7 +38,9 @@ func shutdown(
 		probes as much context as possible. Esepcially during the graceful shutdown period.
 		Hence it is recommended to setup an independent server for health checks alone.
 	*/
-	defer healthResp.Shutdown(ctx)
+	defer func() {
+		_ = healthResp.Shutdown(ctx)
+	}()
 
 	/*
 		When a server begins its shutdown process, it first signals Kubernetes (or any other prober)