go: implement readiness library

go-health/liveness.go

@@ -0,0 +1,42 @@
+package health
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// Status of the service liveness.
+type LivenessStatus string
+
+const (
+	// Service is alive and functioning properly.
+	LivenessStatusAlive LivenessStatus = "ok"
+)
+
+// Result of a liveness check.
+type LivenessResult struct {
+	// Status of the service (always LivenessStatusAlive)
+	Status LivenessStatus
+	// Timestamp of the liveness check in milliseconds since Unix epoch
+	Timestamp int64
+}
+
+// Checks if the service is alive.
+func Liveness() LivenessResult {
+	return LivenessResult{
+		Status:    LivenessStatusAlive,
+		Timestamp: time.Now().UnixMilli(),
+	}
+}
+
+// Handler for liveness HTTP requests.
+// Returns a response with status 200 and a JSON body matching LivenessResult.
+func LivenessHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		result := Liveness()
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		json.NewEncoder(w).Encode(result)
+	}
+}