add healthcheck service

cmd/web/main.go

@@ -8,27 +8,30 @@ import (
 	"log/slog"
 	"os"
 	"os/signal"
+	"time"
 
 	"golang.org/x/sync/errgroup"
 
 	"git.loyso.art/frx/devsim"
 	"git.loyso.art/frx/devsim/internal/api/http"
+	"git.loyso.art/frx/devsim/internal/probe"
 	"git.loyso.art/frx/devsim/internal/store"
+	"git.loyso.art/frx/devsim/internal/store/memory"
 	"git.loyso.art/frx/devsim/internal/store/mongo"
 	"git.loyso.art/frx/devsim/internal/store/pg"
 	"git.loyso.art/frx/devsim/pkg/collections"
 )
 
 var availableStoreTypes = collections.NewSet([]string{
-	"pg", "mongo",
+	"pg", "mongo", "memory",
 }...)
 
 func main() {
 	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer cancel()
 
-	log := slog.New(slog.NewJSONHandler(io.Discard, &slog.HandlerOptions{
-		Level: slog.LevelInfo,
+	log := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelDebug,
 	}))
 
 	log.InfoContext(
@@ -79,8 +82,9 @@ func (s *pgSettings) fromEnv() {
 }
 
 type applicationSettings struct {
-	listenAddr string
-	storeType  string
+	listenAddr  string
+	monitorAddr string
+	storeType   string
 
 	pg    pgSettings
 	mongo mongoSettings
@@ -88,9 +92,11 @@ type applicationSettings struct {
 
 func loadConfigFromEnv() applicationSettings {
 	const webaddr = ":9123"
+	const monitoraddr = ":9124"
 
 	var cfg applicationSettings
 	cfg.listenAddr = valueOrDefault(os.Getenv("DEVSIM_HTTP_ADDR"), webaddr)
+	cfg.monitorAddr = valueOrDefault(os.Getenv("DEVSIM_MONITOR_ADDR"), monitoraddr)
 	cfg.storeType = os.Getenv("DEVSIM_STORE_TYPE")
 
 	cfg.pg.fromEnv()
@@ -113,6 +119,8 @@ func (s applicationSettings) validate() (err error) {
 		if s.mongo.DSN == "" {
 			err = errors.Join(err, errors.New("no mongo dsn provided"))
 		}
+	case "memory":
+		// no things to validate
 	}
 
 	if s.listenAddr == "" {
@@ -131,6 +139,28 @@ func app(ctx context.Context, settings applicationSettings, log *slog.Logger) (e
 	var repo store.Stats
 	var closers []namedCloser
 
+	livenessBase, livenessToggle := probe.SimpleLivenessSwitcher()
+	readinessBase, readinessToggle := probe.SimpleReadinessSwitcher()
+
+	pr := probe.NewReporter(time.Second * 15)
+	pr.RegisterLiveness(livenessBase)
+	pr.RegisterReadiness(readinessBase)
+
+	mb := http.NewHandlersBuilder()
+	mb.MountProbeHandlers(pr)
+
+	monitorServer := http.NewServer(settings.monitorAddr)
+	closers = append(closers, namedCloser{
+		name:   "monitorhttp",
+		closer: monitorServer,
+	})
+	monitorServer.RegisterHandler(mb.Build())
+
+	eg, _ := errgroup.WithContext(ctx)
+	eg.Go(func() error {
+		return monitorServer.Run()
+	})
+
 	switch settings.storeType {
 	case "pg":
 		pgconn, errDial := pg.Dial(ctx, settings.pg.DSN)
@@ -154,6 +184,8 @@ func app(ctx context.Context, settings applicationSettings, log *slog.Logger) (e
 			name:   "mongo",
 			closer: mongoconn,
 		})
+	case "memory":
+		repo = memory.NewStore()
 	}
 
 	hb := http.NewHandlersBuilder()
@@ -166,22 +198,32 @@ func app(ctx context.Context, settings applicationSettings, log *slog.Logger) (e
 	})
 	httpServer.RegisterHandler(hb.Build())
 
-	eg, _ := errgroup.WithContext(ctx)
 	eg.Go(func() error {
 		return httpServer.Run()
 	})
+	eg.Go(func() error {
+		<-ctx.Done()
+		log.InfoContext(ctx, "got interruption signal")
+		for _, closer := range closers {
+			name := closer.name
+			closerUnit := closer.closer
+			errClose := closerUnit.Close()
+			if errClose != nil {
+				log.ErrorContext(ctx, "unable to close component", slog.String("component", name), slog.Any("err", errClose))
+			}
+		}
+		return nil
+	})
+
+	livenessToggle()
+	readinessToggle(probe.ReadinessOk)
 
 	err = eg.Wait()
 	if err != nil {
-		log.ErrorContext(ctx, "unable to proceed the app", slog.Any("err", err))
-	}
-
-	for _, closer := range closers {
-		name := closer.name
-		closerUnit := closer.closer
-		errClose := closerUnit.Close()
-		if errClose != nil {
-			log.ErrorContext(ctx, "unable to close component", slog.String("component", name), slog.Any("err", errClose))
+		if !errors.Is(err, context.Canceled) {
+			log.ErrorContext(ctx, "unable to proceed the app", slog.Any("err", err))
+		} else {
+			log.InfoContext(ctx, "finished processing apps")
 		}
 	}