[chore]: added dependency prober

Author: bnkamalesh

inits.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/naughtygopher/errors"
 	"github.com/naughtygopher/proberesponder"
+	"github.com/naughtygopher/proberesponder/extensions/depprober"
 	proberespHTTP "github.com/naughtygopher/proberesponder/extensions/http"
 	"github.com/naughtygopher/webgo/v7"
 
@@ -47,6 +48,12 @@ func startServers(svr api.Server, cfgs *configs.Configs, fatalErr chan<- error)
 	}
 
 	go func() {
+		defer func() {
+			rec := recover()
+			if rec != nil {
+				fatalErr <- errors.New(fmt.Sprintf("%+v", rec))
+			}
+		}()
 		err = hserver.Start()
 		if err != nil {
 			fatalErr <- errors.Wrap(err, "failed to start HTTP server")
@@ -98,6 +105,7 @@ func startHealthResponder(ctx context.Context, ps *proberesponder.ProbeResponder
 
 func start(
 	ctx context.Context,
+	probestatus *proberesponder.ProbeResponder,
 	cfgs *configs.Configs,
 	fatalErr chan<- error,
 ) (hserver *xhttp.HTTP, gserver *grpc.GRPC) {
@@ -107,6 +115,18 @@ func start(
 		panic(errors.Wrap(err))
 	}
 
+	depprober.Start(time.Minute, probestatus, &depprober.Probe{
+		ID:               "postgres",
+		AffectedStatuses: []proberesponder.Statuskey{proberesponder.StatusLive, proberesponder.StatusReady},
+		Checker: depprober.CheckerFunc(func(ctx context.Context) error {
+			err := pqdriver.Ping(ctx)
+			if err != nil {
+				return errors.Wrap(err, "postgres ping failed")
+			}
+			return nil
+		}),
+	})
+
 	userPGstore := users.NewPostgresStore(pqdriver, cfgs.UserPostgresTable())
 	userSvc := users.NewService(userPGstore)
 	svrAPIs := api.NewServer(userSvc, nil)

main.go

@@ -18,7 +18,7 @@ import (
 // So that even if the main function panics we can produce required logs for troubleshooting
 var exitErr error
 
-func recoverer(ctx context.Context) {
+func recoverer() {
 	exitCode := 0
 	var exitInfo any
 	rec := recover()
@@ -39,6 +39,7 @@ func recoverer(ctx context.Context) {
 		exitCode = 0
 	}
 
+	ctx := context.Background()
 	// logging this because we have info logs saying "listening to" various port numbers
 	// based on the server type (gRPC, HTTP etc.). But it's unclear *from the logs*
 	// if the server is up and running, if it exits for any reason
@@ -52,14 +53,14 @@ func recoverer(ctx context.Context) {
 }
 
 func main() {
+	defer recoverer()
 	var (
 		ctx                 = context.Background()
 		fatalErr            = make(chan error, 1)
 		shutdownGraceperiod = time.Minute
 		probeInterval       = time.Second * 3
 		probestatus         = proberesponder.New()
 	)
-	defer recoverer(ctx)
 
 	cfgs, err := configs.New()
 	if err != nil {
@@ -78,7 +79,7 @@ func main() {
 		panic(err)
 	}
 
-	hserver, gserver := start(ctx, cfgs, fatalErr)
+	hserver, gserver := start(ctx, probestatus, cfgs, fatalErr)
 
 	// by now all the intended servers, subscribers etc. are up and running.
 	probestatus.SetNotStarted(false)

shutdown.go

@@ -70,26 +70,32 @@ func shutdownDependenciesAndServices(
 	apmIns *apm.APM,
 ) {
 	wgroup := &sync.WaitGroup{}
-	wgroup.Add(1)
-	go func() {
-		defer wgroup.Done()
-		_ = httpServer.Shutdown(ctx)
-	}()
+	if httpServer != nil {
+		wgroup.Add(1)
+		go func() {
+			defer wgroup.Done()
+			_ = httpServer.Shutdown(ctx)
+		}()
+	}
 
-	wgroup.Add(1)
-	go func() {
-		defer wgroup.Done()
-		_ = grpcServer.Shutdown(ctx)
-	}()
+	if grpcServer != nil {
+		wgroup.Add(1)
+		go func() {
+			defer wgroup.Done()
+			_ = grpcServer.Shutdown(ctx)
+		}()
+	}
 
 	// after all the APIs of the application are shutdown (e.g. HTTP, gRPC, Pubsub listener etc.)
 	// we should close connections to dependencies like database, cache etc.
 	// This should only be done after the APIs are shutdown completely
-	wgroup.Add(1)
-	go func() {
-		defer wgroup.Done()
-		_ = apmIns.Shutdown(ctx)
-	}()
+	if apmIns != nil {
+		wgroup.Add(1)
+		go func() {
+			defer wgroup.Done()
+			_ = apmIns.Shutdown(ctx)
+		}()
+	}
 
 	wgroup.Wait()
 }