feat(metrics): distinguish received and acknowledged CDRs

app/api/metrics.py

@@ -10,27 +10,41 @@ class APIMetrics:
     def __init__(self):
         self._lock = threading.Lock()
         self._received_total: int = 0
+        self._acknowledged_total: int = 0
 
     def increment_received(self, count: int = 1) -> None:
         with self._lock:
             self._received_total += count
 
+    def increment_acknowledged(self, count: int = 1) -> None:
+        with self._lock:
+            self._acknowledged_total += count
+
     @property
     def total_received(self) -> int:
         with self._lock:
             return self._received_total
 
+    @property
+    def total_acknowledged(self) -> int:
+        with self._lock:
+            return self._acknowledged_total
+
     def get_prometheus_metrics(self) -> str:
         """
         Formats metrics into standard Prometheus text format.
         """
         with self._lock:
-            val = self._received_total
+            val_received = self._received_total
+            val_ack = self._acknowledged_total
 
         return (
             "# HELP cdr_api_received_total Total CDRs received by the API\n"
             "# TYPE cdr_api_received_total counter\n"
-            f"cdr_api_received_total {val}\n"
+            f"cdr_api_received_total {val_received}\n"
+            "# HELP cdr_api_acknowledged_total Total CDRs successfully acknowledged by Kafka\n"
+            "# TYPE cdr_api_acknowledged_total counter\n"
+            f"cdr_api_acknowledged_total {val_ack}\n"
         )