chore(llmobs): handle error from getting agent info [backport 3.4] (#13089)

Backport 9e21081 from #13049 to 3.4.

Handles an error when trying to get agent info. This should be included
with the initial change to check agent info to determine if LLM
Observability should run agentless or agent-proxy.

Direct fix for #12911, which
hasn't landed yet, hence making this a `chore`. The original release
note for the above PR should suffice for the release.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Co-authored-by: Sam Brenner <[email protected]>

Author: github-actions[bot]

ddtrace/llmobs/_writer.py

@@ -75,7 +75,12 @@ def should_use_agentless(user_defined_agentless_enabled: Optional[bool] = None)
     if user_defined_agentless_enabled is not None:
         return user_defined_agentless_enabled
 
-    agent_info: Optional[Dict[str, Any]] = agent.info()
+    agent_info: Optional[Dict[str, Any]]
+
+    try:
+        agent_info = agent.info()
+    except Exception:
+        agent_info = None
 
     if agent_info is None:
         return True

tests/llmobs/conftest.py

@@ -305,23 +305,23 @@ def llmobs_events(llmobs, llmobs_span_writer):
 
 @pytest.fixture
 def agent():
-    patcher = mock.patch("ddtrace.internal.agent.info", return_value={"endpoints": ["/evp_proxy/v2/"]})
-    patcher.start()
-    yield
-    patcher.stop()
+    with mock.patch("ddtrace.internal.agent.info", return_value={"endpoints": ["/evp_proxy/v2/"]}):
+        yield
 
 
 @pytest.fixture
 def agent_missing_proxy():
-    patcher = mock.patch("ddtrace.internal.agent.info", return_value={"endpoints": []})
-    patcher.start()
-    yield
-    patcher.stop()
+    with mock.patch("ddtrace.internal.agent.info", return_value={"endpoints": []}):
+        yield
+
+
+@pytest.fixture
+def no_agent_info():
+    with mock.patch("ddtrace.internal.agent.info", return_value=None):
+        yield
 
 
 @pytest.fixture
 def no_agent():
-    patcher = mock.patch("ddtrace.internal.agent.info", return_value=None)
-    patcher.start()
-    yield
-    patcher.stop()
+    with mock.patch("ddtrace.internal.agent.info", side_effect=Exception):
+        yield

tests/llmobs/test_llmobs_service.py

@@ -88,6 +88,18 @@ def test_enable_agent_proxy_when_agent_is_available(agent):
         llmobs_service.disable()
 
 
+def test_enable_agentless_when_agent_info_is_not_available(no_agent_info):
+    with override_global_config(dict(_dd_api_key="<not-a-real-api-key>", _llmobs_ml_app="<ml-app-name>")):
+        dummy_tracer = DummyTracer()
+        llmobs_service.enable(_tracer=dummy_tracer)
+        llmobs_instance = llmobs_service._instance
+        assert llmobs_instance is not None
+        assert llmobs_service.enabled
+        assert isinstance(llmobs_instance._llmobs_span_writer._clients[0], LLMObsAgentlessEventClient)
+
+        llmobs_service.disable()
+
+
 def test_enable_agentless_when_agent_is_not_available(no_agent):
     with override_global_config(dict(_dd_api_key="<not-a-real-api-key>", _llmobs_ml_app="<ml-app-name>")):
         dummy_tracer = DummyTracer()