fix(debugger): correct agent endpoint matching

The agent's /info endpoints list may or may not include a leading slash
depending on the agent version. The signal uploader only matched the
leading-slash form, so newer agents that advertise the debugger endpoints
without one were misreported as unsupported: snapshot and log uploads were
disabled and an "unsupported agent" warning was logged on every upload
cycle (as often as once per second).

Normalize the advertised endpoints before matching, consistent with remote
config and CI visibility. Also throttle the agent capability check so /info
is not polled every tick, bounding the warning when the agent genuinely
lacks the required endpoints.

Author: tylfin

ddtrace/debugging/_uploader.py

@@ -118,18 +118,20 @@ def info_check(self, agent_info: Optional[dict[str, Any]]) -> bool:
             log.debug("Unsupported Datadog agent detected. Please upgrade to 7.49.0.")
             return False
 
-        endpoints = set(agent_info.get("endpoints", []))
+        # Agent /info entries may or may not carry a leading slash depending on
+        # the agent version, so normalize before matching (see remoteconfig).
+        endpoints = {endpoint.lstrip("/") for endpoint in agent_info.get("endpoints", [])}
 
         logs_track = self._tracks[SignalTrack.LOGS]
         snapshot_track = self._tracks[SignalTrack.SNAPSHOT]
         logs_track.enabled = True
         snapshot_track.enabled = True
 
-        if "/debugger/v2/input" in endpoints:
+        if "debugger/v2/input" in endpoints:
             log.debug("Detected /debugger/v2/input endpoint")
             logs_track.endpoint = f"/debugger/v2/input{self._endpoint_suffix}"
             snapshot_track.endpoint = f"/debugger/v2/input{self._endpoint_suffix}"
-        elif "/debugger/v1/diagnostics" in endpoints:
+        elif "debugger/v1/diagnostics" in endpoints:
             log.debug("Detected /debugger/v1/diagnostics endpoint fallback")
             logs_track.endpoint = f"/debugger/v1/diagnostics{self._endpoint_suffix}"
             snapshot_track.endpoint = f"/debugger/v1/diagnostics{self._endpoint_suffix}"

ddtrace/internal/agent.py

@@ -7,12 +7,16 @@
 from ddtrace.internal.periodic import ForksafeAwakeablePeriodicService
 from ddtrace.internal.process_tags import compute_base_hash
 from ddtrace.internal.settings._agent import config
+from ddtrace.internal.utils.time import HourGlass
 
 from .utils.http import get_connection
 
 
 log = get_logger(__name__)
 
+# Bound how often /info is polled while the agent is unreachable or unsupported.
+AGENT_CHECK_INTERVAL = 60.0
+
 
 def process_info_headers(resp):
     try:
@@ -51,11 +55,16 @@ def __init__(self, interval: float = 0.0):
         super().__init__(interval=interval)
 
         self._state = self._agent_check
+        self._agent_check_throttle = HourGlass(duration=AGENT_CHECK_INTERVAL)
 
     @abc.abstractmethod
     def info_check(self, agent_info: t.Optional[dict]) -> bool: ...
 
     def _agent_check(self) -> None:
+        if self._agent_check_throttle.trickling():
+            return
+        self._agent_check_throttle.turn()
+
         try:
             agent_info = info()
         except Exception:

releasenotes/notes/fix-debugger-unsupported-agent-log-spam-c0e1179f7ec7c872.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Dynamic Instrumentation, Exception Replay, and Code Origin for Spans: This fix resolves an issue where a
+    supported Datadog Agent could sometimes be incorrectly reported as unsupported, disabling data uploads and
+    producing repeated warning logs.

tests/debugging/test_uploader.py

@@ -114,16 +114,17 @@ def test_info_check_endpoint_selection():
     from ddtrace.debugging._signal.model import SignalTrack
     from ddtrace.debugging._uploader import SignalUploader
 
-    # Test 1: v2 endpoint available - both tracks use v2
+    # Test 1: v2 endpoint available (agent reports endpoints without a leading
+    # slash) - both tracks use v2
     uploader = SignalUploader(interval=LONG_INTERVAL)
-    agent_info = {"endpoints": ["/debugger/v2/input", "/debugger/v1/diagnostics"]}
+    agent_info = {"endpoints": ["debugger/v2/input", "debugger/v1/diagnostics"]}
     assert uploader.info_check(agent_info) is True
     assert uploader._tracks[SignalTrack.LOGS].enabled is True
     assert uploader._tracks[SignalTrack.SNAPSHOT].enabled is True
     assert "/debugger/v2/input" in uploader._tracks[SignalTrack.LOGS].endpoint
     assert "/debugger/v2/input" in uploader._tracks[SignalTrack.SNAPSHOT].endpoint
 
-    # Test 2: Only diagnostics available - both tracks fallback to diagnostics
+    # Test 2: Only diagnostics available (leading-slash form) - both tracks fallback
     uploader = SignalUploader(interval=LONG_INTERVAL)
     agent_info = {"endpoints": ["/debugger/v1/diagnostics"]}
     assert uploader.info_check(agent_info) is True
@@ -313,6 +314,22 @@ def test_online_raises_when_tracks_disabled():
         uploader.online()
 
 
+def test_agent_check_is_throttled():
+    # A missing/unsupported agent must not cause /info to be polled on every
+    # periodic tick; the check is throttled independently of the upload interval.
+    from ddtrace.internal import agent as agent_module
+
+    uploader = SignalUploader(interval=LONG_INTERVAL)
+    agent_info = {"endpoints": ["/some/other/endpoint"]}
+
+    with patch.object(agent_module, "info", return_value=agent_info) as mock_info:
+        uploader._agent_check()
+        uploader._agent_check()
+
+    assert mock_info.call_count == 1
+    assert uploader._state == uploader._agent_check
+
+
 class _IsolatedUploader(MockSignalUploader):
     """Subclass to isolate class-level _products/_instance state from production code."""