Added app package and health check funcs

env-sample

@@ -0,0 +1,14 @@
+# App Config
+APP_NAME="go-http-server-with-otel"
+APP_LOG_LEVEL=trace ## For testing only
+APP_LOG_FORMAT=console ## console, json
+APP_LOG_TIME_FORMAT=long ## long, short, unix, rfc3339, off
+
+# App OTEL Config
+APP_OTEL_STDOUT_ENABLED=true ## For testing only
+APP_OTEL_METRIC_INTERVAL_SECS=15
+
+# OTEL SDK Config
+OTEL_EXPORTER_OTLP_ENDPOINT="otel-collector.otel.svc.cluster.local" # Set to your otel collector
+OTEL_SERVICE_NAME="go-http-server-with-otel"
+OTEL_RESOURCE_ATTRIBUTES="env=development,service.version=(devel)"

main.go

@@ -14,17 +14,13 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
-	"sync"
-	"time"
 
 	"github.com/rs/zerolog"
-	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/trace"
 	"golang.org/x/sys/unix"
 
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/app"
 	"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/otel"
 	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/srv"
 )
 
@@ -38,100 +34,29 @@ func main() {
 	ctx, cncl := signal.NotifyContext(context.Background(), os.Interrupt, unix.SIGTERM)
 	defer cncl()
 
-	shutdownFuncs := make([]func(context.Context) error, 0)
-
 	// Load configuration and setup logging
-	ctx = setupConfigAndLogging(ctx)
+	ctx = app.MustSetupConfigAndLogging(ctx)
 
-	// Set up OTEL
+	// Prepare app
-	ctx, otelShutdown := otel.Init(ctx)
+	app := &app.App{
-	shutdownFuncs = append(shutdownFuncs, otelShutdown)
+		AppContext: ctx,
-	tracer = otel.MustTracerFromCtx(ctx)
+		HTTP: &app.AppHTTP{
-
+			Funcs: []srv.HTTPFunc{
-	// Start App
-	ctx, initSpan := tracer.Start(ctx, "init")
-
-	// Start HTTP Server
-	dummyFuncs := []srv.HTTPFunc{
 				{
-			Path: "/dummy",
+					Path: "/test",
 					HandlerFunc: func(w http.ResponseWriter, r *http.Request) {
-				w.Write([]byte("hello world"))
+						w.WriteHeader(http.StatusNotImplemented)
+						w.Write([]byte("http test route"))
+					},
+				},
 			},
 		},
 	}
-	httpShutdown, httpDone := srv.MustInitHTTPServer(ctx, dummyFuncs...)
-	shutdownFuncs = append(shutdownFuncs, httpShutdown)
 
-	// Startup Complete
+	// Launch app
-	l.Info().
+	app.MustRun()
-		Str("name", cfg.Name).
-		Str("version", cfg.Version).
-		Str("logLevel", cfg.Logging.Level).
-		Msg("app initialized")
-	initSpan.SetStatus(codes.Ok, "")
-	initSpan.End()
 
-	// Wait for signal
+	// Wait for app to complete
-	select {
+	// Perform any extra shutdown here
-	case <-httpDone:
+	<-app.Done()
-		l.Warn().Msg("shutting down early on http server done")
-	case <-ctx.Done():
-		l.Warn().Str("reason", ctx.Err().Error()).
-			Msg("shutting down on context done")
-	}
-	shutdown(shutdownFuncs...)
-}
-
-func shutdown(shutdownFuncs ...func(context.Context) error) {
-	now := time.Now()
-
-	doneCtx, cncl := context.WithTimeout(context.Background(), 15*time.Second)
-	defer func() {
-		if doneCtx.Err() == context.DeadlineExceeded {
-			l.Err(doneCtx.Err()).
-				Dur("shutdownTime", time.Since(now)).
-				Msg("app shutdown aborted")
-		} else {
-			l.Info().
-				Int("shutdownFuncsCalled", len(shutdownFuncs)).
-				Dur("shutdownTime", time.Since(now)).
-				Msg("app shutdown normally")
-		}
-		cncl()
-	}()
-
-	doneCtx, span := tracer.Start(doneCtx, "shutdown")
-	defer span.End()
-
-	var wg sync.WaitGroup
-	wg.Add(len(shutdownFuncs))
-
-	for _, f := range shutdownFuncs {
-		go func() {
-			defer wg.Done()
-			err := f(doneCtx)
-			if err != nil {
-				span.SetStatus(codes.Error, "shutdown failed")
-				span.RecordError(err)
-				l.Err(err).Send()
-			}
-		}()
-	}
-
-	wg.Wait()
-}
-
-func setupConfigAndLogging(ctx context.Context) context.Context {
-	ctx, err := config.LoadConfig(ctx)
-	if err != nil {
-		panic(err)
-	}
-
-	cfg = config.MustFromCtx(ctx)
-	ctx = logging.MustInitLogging(ctx)
-	l = zerolog.Ctx(ctx)
-
-	l.Trace().Any("config", *cfg).Send()
-	return ctx
 }

pkg/app/app.go

@@ -0,0 +1,93 @@
+package app
+
+import (
+	"context"
+	"errors"
+
+	"github.com/rs/zerolog"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/config"
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/otel"
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/srv"
+)
+
+type App struct {
+	AppContext    context.Context
+	HTTP          *AppHTTP
+	cfg           *config.AppConfig
+	l             *zerolog.Logger
+	tracer        trace.Tracer
+	shutdownFuncs []shutdownFunc
+	appDone       chan interface{}
+}
+
+type AppHTTP struct {
+	Funcs        []srv.HTTPFunc
+	HealthChecks []srv.HealthCheckFunc
+	httpDone     <-chan interface{}
+}
+
+type (
+	healthCheckFunc func(context.Context) error
+	shutdownFunc    func(context.Context) error
+)
+
+func (a *App) Done() <-chan interface{} {
+	return a.appDone
+}
+
+func (a *App) MustRun() {
+	if a.cfg != nil {
+		panic(errors.New("already ran app trying to run"))
+	}
+
+	// Set up app
+	a.cfg = config.MustFromCtx(a.AppContext)
+	a.l = zerolog.Ctx(a.AppContext)
+	a.shutdownFuncs = make([]shutdownFunc, 0)
+	a.appDone = make(chan interface{})
+	a.HTTP.httpDone = make(chan interface{})
+
+	if len(a.HTTP.Funcs) < 1 {
+		a.l.Warn().Msg("no http funcs provided, only serving health and metrics")
+	}
+
+	// Start OTEL
+	a.initOTEL()
+	var initSpan trace.Span
+	_, initSpan = a.tracer.Start(a.AppContext, "init")
+
+	// Start HTTP
+	a.initHTTP()
+
+	// Monitor app lifecycle
+	go a.run()
+
+	// Startup Complete
+	a.l.Info().
+		Str("name", a.cfg.Name).
+		Str("version", a.cfg.Version).
+		Str("logLevel", a.cfg.Logging.Level).
+		Msg("app initialized")
+	initSpan.SetStatus(codes.Ok, "")
+	initSpan.End()
+}
+
+func (a *App) initHTTP() {
+	var httpShutdown shutdownFunc
+	httpShutdown, a.HTTP.httpDone = srv.MustInitHTTPServer(
+		a.AppContext,
+		a.HTTP.Funcs,
+		a.HTTP.HealthChecks...,
+	)
+	a.shutdownFuncs = append(a.shutdownFuncs, httpShutdown)
+}
+
+func (a *App) initOTEL() {
+	var otelShutdown shutdownFunc
+	a.AppContext, otelShutdown = otel.Init(a.AppContext)
+	a.shutdownFuncs = append(a.shutdownFuncs, otelShutdown)
+	a.tracer = otel.MustTracerFromCtx(a.AppContext)
+}

pkg/app/run.go

@@ -0,0 +1,67 @@
+package app
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"go.opentelemetry.io/otel/codes"
+)
+
+// Watches contexts and channels for the
+// app to be finished and calls shutdown once
+// the app is done
+func (a *App) run() {
+	select {
+	case <-a.AppContext.Done():
+		a.l.Warn().Str("reason", a.AppContext.Err().Error()).
+			Msg("shutting down on context done")
+	case <-a.HTTP.httpDone:
+		a.l.Warn().Msg("shutting down early on http server done")
+	}
+	a.Shutdown()
+
+	a.appDone <- nil
+}
+
+// Typically invoked when AppContext is done
+// or Server has exited. Not intended to be called
+// manually
+func (a *App) Shutdown() {
+	now := time.Now()
+
+	doneCtx, cncl := context.WithTimeout(context.Background(), 15*time.Second)
+	defer func() {
+		if doneCtx.Err() == context.DeadlineExceeded {
+			a.l.Err(doneCtx.Err()).
+				Dur("shutdownTime", time.Since(now)).
+				Msg("app shutdown aborted")
+		} else {
+			a.l.Info().
+				Int("shutdownFuncsCalled", len(a.shutdownFuncs)).
+				Dur("shutdownTime", time.Since(now)).
+				Msg("app shutdown normally")
+		}
+		cncl()
+	}()
+
+	doneCtx, span := a.tracer.Start(doneCtx, "shutdown")
+	defer span.End()
+
+	var wg sync.WaitGroup
+	wg.Add(len(a.shutdownFuncs))
+
+	for _, f := range a.shutdownFuncs {
+		go func() {
+			defer wg.Done()
+			err := f(doneCtx)
+			if err != nil {
+				span.SetStatus(codes.Error, "shutdown failed")
+				span.RecordError(err)
+				a.l.Err(err).Send()
+			}
+		}()
+	}
+
+	wg.Wait()
+}

pkg/app/setup.go

@@ -0,0 +1,25 @@
+package app
+
+import (
+	"context"
+
+	"github.com/rs/zerolog"
+
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/config"
+	"gitea.libretechconsulting.com/rmcguire/go-http-server-with-otel/pkg/logging"
+)
+
+// Helper function to return a context loaded up with
+// config.AppConfig and a logger
+func MustSetupConfigAndLogging(ctx context.Context) context.Context {
+	ctx, err := config.LoadConfig(ctx)
+	if err != nil {
+		panic(err)
+	}
+
+	cfg := config.MustFromCtx(ctx)
+	ctx = logging.MustInitLogging(ctx)
+
+	zerolog.Ctx(ctx).Trace().Any("config", *cfg).Send()
+	return ctx
+}

pkg/srv/http.go

@@ -29,7 +29,7 @@ type HTTPFunc struct {
 	HandlerFunc http.HandlerFunc
 }
 
-func prepHTTPServer(ctx context.Context, handleFuncs ...HTTPFunc) *http.Server {
+func prepHTTPServer(ctx context.Context, handleFuncs []HTTPFunc, hcFuncs ...HealthCheckFunc) *http.Server {
 	var (
 		cfg = config.MustFromCtx(ctx)
 		l   = zerolog.Ctx(ctx)
@@ -43,8 +43,9 @@ func prepHTTPServer(ctx context.Context, handleFuncs ...HTTPFunc) *http.Server {
 		mux.Handle(pattern, handler) // Associate pattern with handler
 	}
 
-	otelHandleFunc("/health", handleHealthCheckFunc(ctx))
+	healthChecks := handleHealthCheckFunc(ctx, hcFuncs...)
-	otelHandleFunc("/", handleHealthCheckFunc(ctx))
+	otelHandleFunc("/health", healthChecks)
+	otelHandleFunc("/", healthChecks)
 
 	for _, f := range handleFuncs {
 		otelHandleFunc(f.Path, f.HandlerFunc)
@@ -85,8 +86,10 @@ func prepHTTPServer(ctx context.Context, handleFuncs ...HTTPFunc) *http.Server {
 
 // Returns a shutdown func and a done channel if the
 // server aborts abnormally. Panics on error.
-func MustInitHTTPServer(ctx context.Context, funcs ...HTTPFunc) (func(context.Context) error, <-chan interface{}) {
+func MustInitHTTPServer(ctx context.Context, funcs []HTTPFunc, hcFuncs ...HealthCheckFunc) (
-	shutdownFunc, doneChan, err := InitHTTPServer(ctx, funcs...)
+	func(context.Context) error, <-chan interface{},
+) {
+	shutdownFunc, doneChan, err := InitHTTPServer(ctx, funcs, hcFuncs...)
 	if err != nil {
 		panic(err)
 	}
@@ -95,7 +98,9 @@ func MustInitHTTPServer(ctx context.Context, funcs ...HTTPFunc) (func(context.Co
 
 // Returns a shutdown func and a done channel if the
 // server aborts abnormally. Returns error on failure to start
-func InitHTTPServer(ctx context.Context, funcs ...HTTPFunc) (func(context.Context) error, <-chan interface{}, error) {
+func InitHTTPServer(ctx context.Context, funcs []HTTPFunc, hcFuncs ...HealthCheckFunc) (
+	func(context.Context) error, <-chan interface{}, error,
+) {
 	l := zerolog.Ctx(ctx)
 	doneChan := make(chan interface{})
 
@@ -104,7 +109,7 @@ func InitHTTPServer(ctx context.Context, funcs ...HTTPFunc) (func(context.Contex
 	httpMeter = otel.GetMeter(ctx, "http")
 	httpTracer = otel.GetTracer(ctx, "http")
 
-	server = prepHTTPServer(ctx, funcs...)
+	server = prepHTTPServer(ctx, funcs, hcFuncs...)
 
 	go func() {
 		l.Debug().Msg("HTTP Server Started")

pkg/srv/http_health.go

@@ -7,39 +7,47 @@ import (
 	"net/http"
 	"sync"
 	"time"
+
+	"github.com/rs/zerolog"
 )
 
-func handleHealthCheckFunc(_ context.Context) func(w http.ResponseWriter, r *http.Request) {
+type HealthCheckFunc func(context.Context) error
+
+func handleHealthCheckFunc(ctx context.Context, hcFuncs ...HealthCheckFunc) func(w http.ResponseWriter, r *http.Request) {
 	// Return http handle func
 	return func(w http.ResponseWriter, r *http.Request) {
-		var err error
+		var (
-		var healthChecksFailed bool
+			healthChecksFailed bool
+			errs               error
+			hcWg               sync.WaitGroup
+		)
 
-		// TODO: Insert useful health checks here
+		if len(hcFuncs) < 1 {
-		// For multiple checks, perform concurrently
+			zerolog.Ctx(ctx).Warn().Msg("no health checks given responding with dummy 200")
-		// Consider using errors.Join() for multiple checks
+			hcFuncs = append(hcFuncs, dummyHealthCheck)
-		var hcWg sync.WaitGroup
+		}
-		for range 5 {
+
-			hcWg.Add(1)
+		// Run all health check funcs concurrently
+		// log all errors
+		hcWg.Add(len(hcFuncs))
+		for _, hc := range hcFuncs {
 			go func() {
 				defer hcWg.Done()
-				err = errors.Join(err, dummyHealthCheck(r.Context()))
+				errs = errors.Join(errs, hc(ctx))
 			}()
 		}
 		hcWg.Wait()
-		if err != nil {
+
+		if errs != nil {
 			healthChecksFailed = true
 		}
 
-		// TODO: Friendly reminder...
-		err = errors.New("WARNING: Unimplemented health-check")
-
 		if healthChecksFailed {
 			w.WriteHeader(http.StatusInternalServerError)
 		}
 
-		if err != nil {
+		if errs != nil {
-			w.Write([]byte(err.Error()))
+			w.Write([]byte(errs.Error()))
 		} else {
 			w.Write([]byte("ok"))
 		}