Add /-/healthy and /-/ready endpoints

stackdriver_exporter.go

@@ -287,6 +287,9 @@ func main() {
 		http.Handle(*metricsPath, promhttp.Handler())
 	}
 
+	http.HandleFunc("/-/healthy", healthCheckHandler)
+	http.HandleFunc("/-/ready", healthCheckHandler)
+
 	if *metricsPath != "/" && *metricsPath != "" {
 		landingConfig := web.LandingConfig{
 			Name:        "Stackdriver Exporter",
@@ -297,6 +300,14 @@ func main() {
 					Address: *metricsPath,
 					Text:    "Metrics",
 				},
+				{
+					Address: "/-/healthy",
+					Text:    "Healthy",
+				},
+				{
+					Address: "/-/ready",
+					Text:    "Ready",
+				},
 			},
 		}
 		if *metricsPath != *stackdriverMetricsPath {
@@ -322,6 +333,11 @@ func main() {
 	}
 }
 
+func healthCheckHandler(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	fmt.Fprint(w, "OK")
+}
+
 func collectorConfigFromFlags() *config.Config {
 	return &config.Config{
 		ProjectIDs:                slices.Clone(*projectIDs),

stackdriver_exporter_test.go

@@ -14,6 +14,9 @@
 package main
 
 import (
+	"io"
+	"net/http"
+	"net/http/httptest"
 	"testing"
 	"time"
 
@@ -46,3 +49,31 @@ func TestCollectorConfigFromFlagsDefaultsProjectsRefreshIntervalToDisabled(t *te
 		t.Fatalf("ProjectsRefreshInterval = %v, want default %v", cfg.ProjectsRefreshInterval, config.DefaultProjectsRefreshInterval)
 	}
 }
+
+func TestHealthCheckHandler(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/-/healthy", healthCheckHandler)
+	mux.HandleFunc("/-/ready", healthCheckHandler)
+
+	for _, path := range []string{"/-/healthy", "/-/ready"} {
+		t.Run(path, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, path, nil)
+			rrw := httptest.NewRecorder()
+			mux.ServeHTTP(rrw, req)
+
+			res := rrw.Result()
+			defer res.Body.Close()
+
+			if res.StatusCode != http.StatusOK {
+				t.Fatalf("status = %d, want %d", res.StatusCode, http.StatusOK)
+			}
+			body, err := io.ReadAll(res.Body)
+			if err != nil {
+				t.Fatalf("read body: %v", err)
+			}
+			if got := string(body); got != "OK" {
+				t.Fatalf("body = %q, want %q", got, "OK")
+			}
+		})
+	}
+}