feat: add health check to telemetry server

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

cmd/dex/serve.go

@@ -14,6 +14,9 @@ import (
 	"syscall"
 	"time"
 
+	gosundheit "github.com/AppsFlyer/go-sundheit"
+	"github.com/AppsFlyer/go-sundheit/checks"
+	gosundheithttp "github.com/AppsFlyer/go-sundheit/http"
 	"github.com/ghodss/yaml"
 	grpcprometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/oklog/run"
@@ -325,6 +328,28 @@ func runServe(options serveOptions) error {
 	telemetryServ := http.NewServeMux()
 	telemetryServ.Handle("/metrics", promhttp.HandlerFor(prometheusRegistry, promhttp.HandlerOpts{}))
 
+	// Configure health checker
+	healthChecker := gosundheit.New()
+	{
+		handler := gosundheithttp.HandleHealthJSON(healthChecker)
+		telemetryServ.Handle("/healthz", handler)
+
+		// Kubernetes style health checks
+		telemetryServ.HandleFunc("/healthz/live", func(w http.ResponseWriter, _ *http.Request) {
+			_, _ = w.Write([]byte("ok"))
+		})
+		telemetryServ.Handle("/healthz/ready", handler)
+	}
+
+	healthChecker.RegisterCheck(&gosundheit.Config{
+		Check: &checks.CustomCheck{
+			CheckName: "storage",
+			CheckFunc: storage.NewCustomHealthCheckFunc(serverConfig.Storage, serverConfig.Now),
+		},
+		ExecutionPeriod:  15 * time.Second,
+		InitiallyPassing: true,
+	})
+
 	var gr run.Group
 	if c.Telemetry.HTTP != "" {
 		telemetrySrv := &http.Server{Addr: c.Telemetry.HTTP, Handler: telemetryServ}