POC instrumentation loader

Author: owais

Diff for: opentelemetry-instrumentation/src/opentelemetry/instrumentation/auto_instrumentation/sitecustomize.py

@@ -24,6 +24,7 @@
     OTEL_PYTHON_DISABLED_INSTRUMENTATIONS,
 )
 
+
 logger = getLogger(__file__)
 
 
@@ -40,20 +41,38 @@ def _load_distros():
 
 
 def _load_instrumentors():
+    instrumentation_loader = _default_instrumentation_loader
+    for loader in iter_entry_points("opentelemetry_instrumentation_loader"):
+        logger.debug("loading instrumentations with %s", loader.name)
+        instrumentation_loader = loader.load()
+        break
+
     package_to_exclude = environ.get(OTEL_PYTHON_DISABLED_INSTRUMENTATIONS, [])
     if isinstance(package_to_exclude, str):
         package_to_exclude = package_to_exclude.split(",")
         # to handle users entering "requests , flask" or "requests, flask" with spaces
         package_to_exclude = [x.strip() for x in package_to_exclude]
 
+    entry_points = []
     for entry_point in iter_entry_points("opentelemetry_instrumentor"):
+        if entry_point.name in package_to_exclude:
+            logger.debug(
+                "Instrumentation skipped for library %s", entry_point.name
+            )
+            continue
+        entry_points.append(entry_point)
+
+    instrumentation_loader(entry_points)
+
+
+def _default_instrumentation_loader(entry_points):
+    for entry_point in entry_points:
         try:
-            if entry_point.name in package_to_exclude:
-                logger.debug(
-                    "Instrumentation skipped for library %s", entry_point.name
-                )
-                continue
-            entry_point.load()().instrument()  # type: ignore
+            # custom loaders can inspect entry_point and
+            # skip loading, load a replacement/fork,
+            # pass additional parameters to constructor
+            # or instrument(), etc
+            entry_point.load()().instrument()
             logger.debug("Instrumented %s", entry_point.name)
         except Exception as exc:  # pylint: disable=broad-except
             logger.exception("Instrumenting of %s failed", entry_point.name)