fix(tracer): handle deleted remote configurations [backport 2.4] (#7940)

Backport 26ede5c from #7933 to 2.4.

The data format changed with the recent refactor the the remoteconfig
client. A `None` value used to be passed to the handling method when a
configuration was deleted.

A test case is added to cover the regression.

No release note is required because the feature isn't released yet.


Co-authored-by: Kyle Verhoog <[email protected]>
Co-authored-by: Munir Abdinur <[email protected]>

Author: 3 people

ddtrace/settings/config.py

@@ -690,27 +690,24 @@ def __init__(self, callback):
 
     def _handle_remoteconfig(self, data, test_tracer=None):
         # type: (Any, Any) -> None
-
-        # If no data is submitted then the RC config has been deleted. Revert the settings.
-        if not data:
-            for item in self._config.values():
-                item.unset_rc()
+        if not isinstance(data, dict) or (isinstance(data, dict) and "config" not in data):
+            log.warning("unexpected RC payload %r", data)
             return
-
         if len(data["config"]) == 0:
             log.warning("unexpected number of RC payloads %r", data)
             return
 
+        # If no data is submitted then the RC config has been deleted. Revert the settings.
         config = data["config"][0]
-        if "lib_config" not in config:
-            log.warning("unexpected RC payload %r", config)
-            return
-
-        lib_config = config["lib_config"]
         updated_items = []  # type: List[Tuple[str, Any]]
 
-        if "tracing_sampling_rate" in lib_config:
-            updated_items.append(("_trace_sample_rate", lib_config["tracing_sampling_rate"]))
+        if not config:
+            for item in self._config:
+                updated_items.append((item, None))
+        else:
+            lib_config = config["lib_config"]
+            if "tracing_sampling_rate" in lib_config:
+                updated_items.append(("_trace_sample_rate", lib_config["tracing_sampling_rate"]))
 
         self._set_config_items([(k, v, "remote_config") for k, v in updated_items])
 

tests/internal/test_settings.py

@@ -32,6 +32,13 @@ def _base_rc_config(cfg):
     }
 
 
+def _deleted_rc_config():
+    return {
+        "metadata": [],
+        "config": [False],
+    }
+
+
 @pytest.mark.parametrize(
     "testcase",
     [
@@ -125,7 +132,7 @@ def test_remoteconfig_sampling_rate_user(run_python_code_in_subprocess):
         """
 from ddtrace import config, tracer
 from ddtrace.sampler import DatadogSampler
-from tests.internal.test_settings import _base_rc_config
+from tests.internal.test_settings import _base_rc_config, _deleted_rc_config
 
 with tracer.trace("test") as span:
     pass
@@ -153,6 +160,16 @@ def test_remoteconfig_sampling_rate_user(run_python_code_in_subprocess):
 assert span.get_metric("_dd.rule_psr") == 0.4
 
 config._handle_remoteconfig(_base_rc_config({"tracing_sampling_rate": None}))
+with tracer.trace("test") as span:
+    pass
+assert span.get_metric("_dd.rule_psr") == 0.3
+
+config._handle_remoteconfig(_base_rc_config({"tracing_sampling_rate": 0.4}))
+with tracer.trace("test") as span:
+    pass
+assert span.get_metric("_dd.rule_psr") == 0.4
+
+config._handle_remoteconfig(_deleted_rc_config())
 with tracer.trace("test") as span:
     pass
 assert span.get_metric("_dd.rule_psr") == 0.3