chore: introduce APM_TRACING RC product

We introduce the APM_TRACING remote configuration product that allows
dispatching remote configuration to the library for remote enablement/
configuration of library components and features.

Author: P403n1x87

ddtrace/debugging/_debugger.py

@@ -275,8 +275,6 @@ def enable(cls) -> None:
 
         di_config.enabled = True
 
-        cls.__watchdog__.install()
-
         if di_config.metrics:
             metrics.enable()
 
@@ -308,7 +306,6 @@ def disable(cls, join: bool = True) -> None:
         cls._instance.stop(join=join)
         cls._instance = None
 
-        cls.__watchdog__.uninstall()
         if di_config.metrics:
             metrics.disable()
 

ddtrace/debugging/_products/dynamic_instrumentation.py

@@ -1,18 +1,28 @@
+from ddtrace.internal.core.event_hub import on
 from ddtrace.settings.dynamic_instrumentation import config
 
 
 requires = ["remote-configuration"]
 
 
 def post_preload():
-    pass
+    from ddtrace.debugging._debugger import Debugger
+
+    # We need to install this on start-up because if DI gets enabled remotely
+    # we won't be able to capture many of the code objects from the modules
+    # that are already loaded.
+    Debugger.__watchdog__.install()
+
+
+def _start():
+    from ddtrace.debugging import DynamicInstrumentation
+
+    DynamicInstrumentation.enable()
 
 
 def start():
     if config.enabled:
-        from ddtrace.debugging import DynamicInstrumentation
-
-        DynamicInstrumentation.enable()
+        _start()
 
 
 def restart(join=False):
@@ -29,3 +39,21 @@ def stop(join=False):
 
 def at_exit(join=False):
     stop(join=join)
+
+
+def apm_tracing_rc(lib_config):
+    enabled = lib_config.get("dynamic_instrumentation_enabled")
+    try:
+        if enabled is not None:  # and config.spec.enabled.full_name not in config.source:
+            if (config.spec.enabled.full_name not in config.source or config.enabled) and enabled:
+                _start()
+            else:
+                stop()
+    except Exception:
+        from traceback import print_exc
+
+        print_exc()
+        raise
+
+
+on("apm-tracing.rc", apm_tracing_rc, "dynamic-instrumentation")

ddtrace/internal/remoteconfig/products/__init__.py

@@ -0,0 +1,69 @@
+from ddtrace import config
+from ddtrace.internal.core.event_hub import dispatch
+from ddtrace.internal.logger import get_logger
+from ddtrace.internal.remoteconfig._connectors import PublisherSubscriberConnector
+from ddtrace.internal.remoteconfig._publishers import RemoteConfigPublisher
+from ddtrace.internal.remoteconfig._pubsub import PubSub
+from ddtrace.internal.remoteconfig._subscribers import RemoteConfigSubscriber
+
+
+requires = ["remote-configuration"]
+
+
+log = get_logger(__name__)
+
+
+def _rc_callback(data, test_tracer=None):
+    for metadata, data in zip(data["metadata"], data["config"]):
+        if metadata is None or not isinstance(data, dict):
+            continue
+
+        service_target = data.get("service_target")
+        if service_target is not None:
+            service = service_target.get("service")
+            if service is not None and service != config.service:
+                continue
+
+            env = service_target.get("env")
+            if env is not None and env != config.env:
+                continue
+
+        lib_config = data.get("lib_config")
+        if lib_config is not None:
+            dispatch("apm-tracing.rc", (lib_config,))
+
+
+class APMTracingAdapter(PubSub):
+    __publisher_class__ = RemoteConfigPublisher
+    __subscriber_class__ = RemoteConfigSubscriber
+    __shared_data__ = PublisherSubscriberConnector()
+
+    def __init__(self):
+        self._publisher = self.__publisher_class__(self.__shared_data__)
+        self._subscriber = self.__subscriber_class__(self.__shared_data__, _rc_callback, "APM_TRACING")
+
+
+def post_preload():
+    pass
+
+
+def start():
+    if config._remote_config_enabled:
+        from ddtrace.internal.remoteconfig.worker import remoteconfig_poller
+
+        remoteconfig_poller.register("APM_TRACING", APMTracingAdapter(), restart_on_fork=True)
+
+
+def restart(join=False):
+    pass
+
+
+def stop(join=False):
+    if config._remote_config_enabled:
+        from ddtrace.internal.remoteconfig.worker import remoteconfig_poller
+
+        remoteconfig_poller.unregister("APM_TRACING")
+
+
+def at_exit(join=False):
+    stop(join=join)

ddtrace/internal/remoteconfig/products/apm_tracing.py

@@ -59,11 +59,12 @@ ddtrace = "ddtrace.contrib.internal.pytest.plugin"
 "ddtrace.pytest_benchmark" = "ddtrace.contrib.internal.pytest_benchmark.plugin"
 
 [project.entry-points.'ddtrace.products']
+"apm-tracing-rc" = "ddtrace.internal.remoteconfig.products.apm_tracing"
 "code-origin-for-spans" = "ddtrace.debugging._products.code_origin.span"
 "dynamic-instrumentation" = "ddtrace.debugging._products.dynamic_instrumentation"
 "exception-replay" = "ddtrace.debugging._products.exception_replay"
 "live-debugger" = "ddtrace.debugging._products.live_debugger"
-"remote-configuration" = "ddtrace.internal.remoteconfig.product"
+"remote-configuration" = "ddtrace.internal.remoteconfig.products.client"
 "symbol-database" = "ddtrace.internal.symbol_db.product"
 "appsec" = "ddtrace.internal.appsec.product"
 "iast" = "ddtrace.internal.iast.product"

ddtrace/internal/remoteconfig/product.py renamed to ddtrace/internal/remoteconfig/products/client.py

@@ -203,7 +203,11 @@ def _debugger(config_to_override: En, config_overrides: Any) -> Generator[TestDe
 def debugger(**config_overrides: Any) -> Generator[TestDebugger, None, None]:
     """Test with the debugger enabled."""
     with _debugger(di_config, config_overrides) as debugger:
-        yield debugger
+        debugger.__watchdog__.install()
+        try:
+            yield debugger
+        finally:
+            debugger.__watchdog__.uninstall()
 
 
 class MockSpanExceptionHandler(SpanExceptionHandler):