fix(cache): log hashed cache keys (#29890)

litellm/caching/caching.py

@@ -309,9 +309,13 @@ class Cache:
                     param_value = kwargs[param]
                     cache_key += f"{str(param)}: {str(param_value)}"
 
-        verbose_logger.debug("\nCreated cache key: %s", cache_key)
         hashed_cache_key = Cache._get_hashed_cache_key(cache_key)
         hashed_cache_key = self._add_namespace_to_cache_key(hashed_cache_key, **kwargs)
+        verbose_logger.debug(
+            "\nCreated cache key: %s (source material length: %d)",
+            hashed_cache_key,
+            len(cache_key),
+        )
         # Remove preset_cache_key from kwargs to avoid "got multiple values" TypeError
         # when kwargs already contains preset_cache_key from upstream callers
         kwargs_for_preset = {k: v for k, v in kwargs.items() if k != "preset_cache_key"}

tests/test_litellm/caching/test_caching.py

@@ -0,0 +1,48 @@
+import logging
+import re
+
+from litellm.caching.caching import Cache
+from litellm.types.caching import LiteLLMCacheType
+
+
+def test_cache_key_debug_log_does_not_include_prompt_material(caplog):
+    cache = Cache(type=LiteLLMCacheType.LOCAL)
+    prompt_marker = "secret prompt material "
+
+    with caplog.at_level(logging.DEBUG, logger="LiteLLM"):
+        cache_key = cache.get_cache_key(
+            model="gpt-4.1-mini",
+            messages=[
+                {"role": "system", "content": prompt_marker * 100},
+                {"role": "user", "content": "hello"},
+            ],
+            tools=[
+                {
+                    "type": "function",
+                    "function": {
+                        "name": "lookup",
+                        "parameters": {
+                            "type": "object",
+                            "properties": {"query": {"type": "string"}},
+                        },
+                    },
+                }
+            ],
+            response_format={
+                "type": "json_schema",
+                "json_schema": {
+                    "name": "lookup_response",
+                    "schema": {"type": "object"},
+                },
+            },
+            stream=True,
+        )
+
+    assert re.fullmatch(r"[0-9a-f]{64}", cache_key)
+
+    created_cache_key_logs = [
+        record.getMessage() for record in caplog.records if "Created cache key:" in record.getMessage()
+    ]
+    assert created_cache_key_logs
+    assert all(prompt_marker not in message for message in created_cache_key_logs)
+    assert any(cache_key in message for message in created_cache_key_logs)