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>

tests/telemetry/test_telemetry_disable.py

@@ -1,5 +1,5 @@
 import os
-from unittest.mock import patch
+from unittest.mock import patch, MagicMock
 
 import pytest
 
@@ -16,6 +16,7 @@ from crewai.telemetry import Telemetry
 ])
 def test_telemetry_environment_variables(env_var, value, expected_ready):
     """Test telemetry state with different environment variable configurations."""
+    Telemetry._instance = None
     with patch.dict(os.environ, {env_var: value}):
         with patch("crewai.telemetry.telemetry.TracerProvider"):
             telemetry = Telemetry()
@@ -24,7 +25,70 @@ def test_telemetry_environment_variables(env_var, value, expected_ready):
 
 def test_telemetry_enabled_by_default():
     """Test that telemetry is enabled by default."""
+    Telemetry._instance = None
     with patch.dict(os.environ, {}, clear=True):
         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."""
+    Telemetry._instance = None
+    
+    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."""
+    Telemetry._instance = None
+    
+    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."""
+    Telemetry._instance = None
+    
+    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()