refactor: update OpenTelemetry initialization to avoid multiple calls (…

…#4306)

* Ensure single initialization of OpenTelemetry and optimize meter provider setup

* Simplify condition by removing redundant class attribute

src/backend/base/langflow/services/telemetry/opentelemetry.py

@@ -1,5 +1,4 @@
 import threading
-import warnings
 from collections.abc import Mapping
 from enum import Enum
 from typing import Any
@@ -110,6 +109,8 @@ class OpenTelemetry(metaclass=ThreadSafeSingletonMetaUsingWeakref):
     _metrics_registry: dict[str, Metric] = {}
     _metrics: dict[str, Counter | ObservableGaugeWrapper | Histogram | UpDownCounter] = {}
     _meter_provider: MeterProvider | None = None
+    _initialized: bool = False  # Add initialization flag
+    prometheus_enabled: bool = True
 
     def _add_metric(
         self, name: str, description: str, unit: str, metric_type: MetricType, labels: dict[str, bool]
@@ -141,20 +142,29 @@ def _register_metric(self) -> None:
         )
 
     def __init__(self, *, prometheus_enabled: bool = True):
+        # Only initialize once
+        self.prometheus_enabled = prometheus_enabled
+        if OpenTelemetry._initialized:
+            return
+
         if not self._metrics_registry:
             self._register_metric()
 
         if self._meter_provider is None:
-            resource = Resource.create({"service.name": "langflow"})
-            metric_readers = []
+            # Get existing meter provider if any
+            existing_provider = metrics.get_meter_provider()
 
-            # configure prometheus exporter
-            self.prometheus_enabled = prometheus_enabled
-            if prometheus_enabled:
-                metric_readers.append(PrometheusMetricReader())
+            # Check if FastAPI instrumentation is already set up
+            if hasattr(existing_provider, "get_meter") and existing_provider.get_meter("http.server"):
+                self._meter_provider = existing_provider
+            else:
+                resource = Resource.create({"service.name": "langflow"})
+                metric_readers = []
+                if self.prometheus_enabled:
+                    metric_readers.append(PrometheusMetricReader())
 
-            self._meter_provider = MeterProvider(resource=resource, metric_readers=metric_readers)
-            metrics.set_meter_provider(self._meter_provider)
+                self._meter_provider = MeterProvider(resource=resource, metric_readers=metric_readers)
+                metrics.set_meter_provider(self._meter_provider)
 
         self.meter = self._meter_provider.get_meter(langflow_meter_name)
 
@@ -163,11 +173,12 @@ def __init__(self, *, prometheus_enabled: bool = True):
                 msg = f"Key '{name}' does not match metric name '{metric.name}'"
                 raise ValueError(msg)
             if name not in self._metrics:
-                with warnings.catch_warnings():
-                    warnings.simplefilter("ignore")
-                    self._metrics[metric.name] = self._create_metric(metric)
+                self._metrics[metric.name] = self._create_metric(metric)
+
+        OpenTelemetry._initialized = True
 
     def _create_metric(self, metric):
+        # Remove _created_instruments check
         if metric.name in self._metrics:
             return self._metrics[metric.name]