fix(utils.py): handle failed hf tokenizer request during calls (#8032)

* fix(utils.py): handle failed hf tokenizer request during calls

prevents proxy from failing due to bad hf tokenizer calls

* fix(utils.py): convert failure callback str to custom logger class

Fixes https://github.com/BerriAI/litellm/issues/8013

* test(test_utils.py): fix test - avoid adding mlflow dep on ci/cd

* fix: add missing env vars to test

* test: cleanup redundant test

litellm/utils.py

@@ -474,6 +474,11 @@ def function_setup(  # noqa: PLR0915
                 if inspect.iscoroutinefunction(callback):
                     litellm._async_failure_callback.append(callback)
                     removed_async_items.append(index)
+                elif (
+                    callback in litellm._known_custom_logger_compatible_callbacks
+                    and isinstance(callback, str)
+                ):
+                    _add_custom_logger_callback_to_specific_event(callback, "failure")
 
             # Pop the async items from failure_callback in reverse order to avoid index issues
             for index in reversed(removed_async_items):
@@ -1385,6 +1390,7 @@ def _select_tokenizer(
 
 @lru_cache(maxsize=128)
 def _select_tokenizer_helper(model: str):
+    try:
         if model in litellm.cohere_models and "command-r" in model:
             # cohere
             cohere_tokenizer = Tokenizer.from_pretrained(
@@ -1403,8 +1409,10 @@ def _select_tokenizer_helper(model: str):
         elif "llama-3" in model.lower():
             tokenizer = Tokenizer.from_pretrained("Xenova/llama-3-tokenizer")
             return {"type": "huggingface_tokenizer", "tokenizer": tokenizer}
+    except Exception as e:
+        verbose_logger.debug(f"Error selecting tokenizer: {e}")
+
     # default - tiktoken
-    else:
     return {
         "type": "openai_tokenizer",
         "tokenizer": encoding,

tests/local_testing/test_token_counter.py

@@ -382,3 +382,80 @@ def test_img_url_token_counter(img_url):
 
 def test_token_encode_disallowed_special():
     encode(model="gpt-3.5-turbo", text="Hello, world! <|endoftext|>")
+
+
+import unittest
+from unittest.mock import patch, MagicMock
+from litellm.utils import encoding, _select_tokenizer_helper, claude_json_str
+
+
+class TestTokenizerSelection(unittest.TestCase):
+    @patch("litellm.utils.Tokenizer.from_pretrained")
+    def test_llama3_tokenizer_api_failure(self, mock_from_pretrained):
+        # Setup mock to raise an error
+        mock_from_pretrained.side_effect = Exception("Failed to load tokenizer")
+
+        # Test with llama-3 model
+        result = _select_tokenizer_helper("llama-3-7b")
+
+        # Verify the attempt to load Llama-3 tokenizer
+        mock_from_pretrained.assert_called_once_with("Xenova/llama-3-tokenizer")
+
+        # Verify fallback to OpenAI tokenizer
+        self.assertEqual(result["type"], "openai_tokenizer")
+        self.assertEqual(result["tokenizer"], encoding)
+
+    @patch("litellm.utils.Tokenizer.from_pretrained")
+    def test_cohere_tokenizer_api_failure(self, mock_from_pretrained):
+        # Setup mock to raise an error
+        mock_from_pretrained.side_effect = Exception("Failed to load tokenizer")
+
+        # Add Cohere model to the list for testing
+        litellm.cohere_models = ["command-r-v1"]
+
+        # Test with Cohere model
+        result = _select_tokenizer_helper("command-r-v1")
+
+        # Verify the attempt to load Cohere tokenizer
+        mock_from_pretrained.assert_called_once_with(
+            "Xenova/c4ai-command-r-v01-tokenizer"
+        )
+
+        # Verify fallback to OpenAI tokenizer
+        self.assertEqual(result["type"], "openai_tokenizer")
+        self.assertEqual(result["tokenizer"], encoding)
+
+    @patch("litellm.utils.Tokenizer.from_str")
+    def test_claude_tokenizer_api_failure(self, mock_from_str):
+        # Setup mock to raise an error
+        mock_from_str.side_effect = Exception("Failed to load tokenizer")
+
+        # Add Claude model to the list for testing
+        litellm.anthropic_models = ["claude-2"]
+
+        # Test with Claude model
+        result = _select_tokenizer_helper("claude-2")
+
+        # Verify the attempt to load Claude tokenizer
+        mock_from_str.assert_called_once_with(claude_json_str)
+
+        # Verify fallback to OpenAI tokenizer
+        self.assertEqual(result["type"], "openai_tokenizer")
+        self.assertEqual(result["tokenizer"], encoding)
+
+    @patch("litellm.utils.Tokenizer.from_pretrained")
+    def test_llama2_tokenizer_api_failure(self, mock_from_pretrained):
+        # Setup mock to raise an error
+        mock_from_pretrained.side_effect = Exception("Failed to load tokenizer")
+
+        # Test with Llama-2 model
+        result = _select_tokenizer_helper("llama-2-7b")
+
+        # Verify the attempt to load Llama-2 tokenizer
+        mock_from_pretrained.assert_called_once_with(
+            "hf-internal-testing/llama-tokenizer"
+        )
+
+        # Verify fallback to OpenAI tokenizer
+        self.assertEqual(result["type"], "openai_tokenizer")
+        self.assertEqual(result["tokenizer"], encoding)

tests/local_testing/test_utils.py

@@ -1529,6 +1529,34 @@ def test_add_custom_logger_callback_to_specific_event_e2e(monkeypatch):
     assert len(litellm.failure_callback) == curr_len_failure_callback
 
 
+def test_add_custom_logger_callback_to_specific_event_e2e_failure(monkeypatch):
+    from litellm.integrations.openmeter import OpenMeterLogger
+
+    monkeypatch.setattr(litellm, "success_callback", [])
+    monkeypatch.setattr(litellm, "failure_callback", [])
+    monkeypatch.setattr(litellm, "callbacks", [])
+    monkeypatch.setenv("OPENMETER_API_KEY", "wedlwe")
+    monkeypatch.setenv("OPENMETER_API_URL", "https://openmeter.dev")
+
+    litellm.failure_callback = ["openmeter"]
+
+    curr_len_success_callback = len(litellm.success_callback)
+    curr_len_failure_callback = len(litellm.failure_callback)
+
+    litellm.completion(
+        model="gpt-4o-mini",
+        messages=[{"role": "user", "content": "Hello, world!"}],
+        mock_response="Testing langfuse",
+    )
+
+    assert len(litellm.success_callback) == curr_len_success_callback
+    assert len(litellm.failure_callback) == curr_len_failure_callback
+
+    assert any(
+        isinstance(callback, OpenMeterLogger) for callback in litellm.failure_callback
+    )
+
+
 @pytest.mark.asyncio
 async def test_wrapper_kwargs_passthrough():
     from litellm.utils import client