Fix telemetry singleton pattern to respect dynamic environment variables (#2946)

* Fix telemetry singleton pattern to respect dynamic environment variables

- Modified Telemetry.__init__ to prevent re-initialization with _initialized flag
- Updated _safe_telemetry_operation to check _is_telemetry_disabled() dynamically
- Added comprehensive tests for environment variables set after singleton creation
- Fixed singleton contamination in existing tests by adding proper reset
- Resolves issue #2945 where CREWAI_DISABLE_TELEMETRY=true was ignored when set after import

Co-Authored-By: João <joao@crewai.com>

* Implement code review improvements

- Move _initialized flag to __new__ method for better encapsulation
- Add type hints to _safe_telemetry_operation method
- Consolidate telemetry execution checks into _should_execute_telemetry helper
- Add pytest fixtures to reduce test setup redundancy
- Enhanced documentation for singleton behavior

Co-Authored-By: João <joao@crewai.com>

* Fix mypy type-checker errors

- Add explicit bool type annotation to _initialized field
- Fix return value in task_started method to not return _safe_telemetry_operation result
- Simplify initialization logic to set _initialized once in __init__

Co-Authored-By: João <joao@crewai.com>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: João <joao@crewai.com>
Co-authored-by: Lorenze Jay <63378463+lorenzejay@users.noreply.github.com>

tests/telemetry/test_telemetry.py

@@ -9,6 +9,14 @@ from crewai.telemetry import Telemetry
 from opentelemetry import trace
 
 
+@pytest.fixture(autouse=True)
+def cleanup_telemetry():
+    """Automatically clean up Telemetry singleton between tests."""
+    Telemetry._instance = None
+    yield
+    Telemetry._instance = None
+
+
 @pytest.mark.parametrize(
     "env_var,value,expected_ready",
     [

tests/telemetry/test_telemetry_disable.py

@@ -1,11 +1,19 @@
 import os
-from unittest.mock import patch
+from unittest.mock import patch, MagicMock
 
 import pytest
 
 from crewai.telemetry import Telemetry
 
 
+@pytest.fixture(autouse=True)
+def cleanup_telemetry():
+    """Automatically clean up Telemetry singleton between tests."""
+    Telemetry._instance = None
+    yield
+    Telemetry._instance = None
+
+
 @pytest.mark.parametrize("env_var,value,expected_ready", [
     ("OTEL_SDK_DISABLED", "true", False),
     ("OTEL_SDK_DISABLED", "TRUE", False),
@@ -28,3 +36,59 @@ def test_telemetry_enabled_by_default():
         with patch("crewai.telemetry.telemetry.TracerProvider"):
             telemetry = Telemetry()
             assert telemetry.ready is True
+
+
+def test_telemetry_disable_after_singleton_creation():
+    """Test that telemetry operations are disabled when env var is set after singleton creation."""
+    with patch.dict(os.environ, {}, clear=True):
+        with patch("crewai.telemetry.telemetry.TracerProvider"):
+            telemetry = Telemetry()
+            assert telemetry.ready is True
+            
+            mock_operation = MagicMock()
+            telemetry._safe_telemetry_operation(mock_operation)
+            mock_operation.assert_called_once()
+            
+            mock_operation.reset_mock()
+            
+            os.environ['CREWAI_DISABLE_TELEMETRY'] = 'true'
+            
+            telemetry._safe_telemetry_operation(mock_operation)
+            mock_operation.assert_not_called()
+
+
+def test_telemetry_disable_with_multiple_instances():
+    """Test that multiple telemetry instances respect dynamically changed env vars."""
+    with patch.dict(os.environ, {}, clear=True):
+        with patch("crewai.telemetry.telemetry.TracerProvider"):
+            telemetry1 = Telemetry()
+            assert telemetry1.ready is True
+            
+            os.environ['CREWAI_DISABLE_TELEMETRY'] = 'true'
+            
+            telemetry2 = Telemetry()
+            assert telemetry2 is telemetry1
+            assert telemetry2.ready is True
+            
+            mock_operation = MagicMock()
+            telemetry2._safe_telemetry_operation(mock_operation)
+            mock_operation.assert_not_called()
+
+
+def test_telemetry_otel_sdk_disabled_after_creation():
+    """Test that OTEL_SDK_DISABLED also works when set after singleton creation."""
+    with patch.dict(os.environ, {}, clear=True):
+        with patch("crewai.telemetry.telemetry.TracerProvider"):
+            telemetry = Telemetry()
+            assert telemetry.ready is True
+            
+            mock_operation = MagicMock()
+            telemetry._safe_telemetry_operation(mock_operation)
+            mock_operation.assert_called_once()
+            
+            mock_operation.reset_mock()
+            
+            os.environ['OTEL_SDK_DISABLED'] = 'true'
+            
+            telemetry._safe_telemetry_operation(mock_operation)
+            mock_operation.assert_not_called()