feat(runtime-metrics): add enabled class property (#2583)

This change adds the `enabled` class property to the runtime metrics API
for checking whether the service has been enabled or not.

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

Author: P403n1x87

ddtrace/internal/runtime/runtime_metrics.py

@@ -77,6 +77,7 @@ class RuntimeWorker(periodic.PeriodicService):
     _runtime_metrics = attr.ib(factory=RuntimeMetrics, repr=False)
     _services = attr.ib(type=Set[str], init=False, factory=set)
 
+    enabled = False
     _instance = None  # type: ClassVar[Optional[RuntimeWorker]]
     _lock = RLock()
 
@@ -108,6 +109,7 @@ def disable(cls):
             cls._instance.stop()
             cls._instance.join()
             cls._instance = None
+            cls.enabled = False
 
     @classmethod
     def _restart(cls):
@@ -128,6 +130,7 @@ def enable(cls, flush_interval=None, tracer=None, dogstatsd_url=None):
             forksafe.register(cls._restart)
 
             cls._instance = runtime_worker
+            cls.enabled = True
 
     def flush(self):
         # type: () -> None

ddtrace/runtime/__init__.py

@@ -1,9 +1,19 @@
 from typing import Optional
 
+import six
+
 import ddtrace.internal.runtime.runtime_metrics
 
 
-class RuntimeMetrics(object):
+class _RuntimeMetricsStatus(type):
+    @property
+    def _enabled(_):
+        # type () -> bool
+        """Runtime metrics enabled status."""
+        return ddtrace.internal.runtime.runtime_metrics.RuntimeWorker.enabled
+
+
+class RuntimeMetrics(six.with_metaclass(_RuntimeMetricsStatus)):
     """
     Runtime metrics service API.
 

tests/runtime/test_runtime_metrics_api.py

@@ -32,38 +32,54 @@ def test_manually_start_runtime_metrics(run_python_code_in_subprocess):
     out, err, status, pid = run_python_code_in_subprocess(
         """
 from ddtrace.runtime import RuntimeMetrics
-RuntimeMetrics.enable()
 
-from ddtrace.internal.runtime.runtime_metrics import RuntimeWorker
-assert RuntimeWorker._instance is not None
+RuntimeMetrics.enable()
+assert RuntimeMetrics._enabled
 
 RuntimeMetrics.disable()
-assert RuntimeWorker._instance is None
+assert not RuntimeMetrics._enabled
 """,
     )
-
     assert status == 0
 
 
-def test_start_runtime_metrics_via_env_var(ddtrace_run_python_code_in_subprocess):
+def test_start_runtime_metrics_via_env_var(monkeypatch, ddtrace_run_python_code_in_subprocess):
     """
     When running with ddtrace-run and DD_RUNTIME_METRICS_ENABLED is set
         Runtime metrics worker starts and there are no errors
     """
 
     _, _, status, _ = ddtrace_run_python_code_in_subprocess(
         """
-from ddtrace.internal.runtime.runtime_metrics import RuntimeWorker
-assert RuntimeWorker._instance is None
+from ddtrace.runtime import RuntimeMetrics
+assert not RuntimeMetrics._enabled
 """
     )
     assert status == 0
 
+    monkeypatch.setenv("DD_RUNTIME_METRICS_ENABLED", "true")
     _, _, status, _ = ddtrace_run_python_code_in_subprocess(
         """
-from ddtrace.internal.runtime.runtime_metrics import RuntimeWorker
-assert RuntimeWorker._instance is not None
+from ddtrace.runtime import RuntimeMetrics
+assert RuntimeMetrics._enabled
+""",
+    )
+    assert status == 0
+
+
+def test_runtime_metrics_via_env_var_manual_start(monkeypatch, ddtrace_run_python_code_in_subprocess):
+    """
+    When running with ddtrace-run and DD_RUNTIME_METRICS_ENABLED is set and trying to start RuntimeMetrics manually
+        Runtime metrics worker starts and there are no errors
+    """
+
+    monkeypatch.setenv("DD_RUNTIME_METRICS_ENABLED", "true")
+    _, _, status, _ = ddtrace_run_python_code_in_subprocess(
+        """
+from ddtrace.runtime import RuntimeMetrics
+assert RuntimeMetrics._enabled
+RuntimeMetrics.enable()
+assert RuntimeMetrics._enabled
 """,
-        env={"DD_RUNTIME_METRICS_ENABLED": "true"},
     )
     assert status == 0