poc(sdk): Add experimental dsn for upcoming perf work (#36000)

This adds an experimental dsn to the MultiplexingTransport to intentionally send specific flagged events solely to a separate dsn, which will help us avoid troubles with ingesting random errors into our main Sentry project.

Author: k-fish

src/sentry/utils/sdk.py

@@ -1,5 +1,6 @@
 import copy
 import inspect
+import random
 
 import sentry_sdk
 from django.conf import settings
@@ -111,6 +112,7 @@
 
 
 UNSAFE_TAG = "_unsafe"
+EXPERIMENT_TAG = "_experimental_event"
 
 
 def is_current_event_safe():
@@ -137,6 +139,16 @@ def is_current_event_safe():
     return True
 
 
+def is_current_event_experimental():
+    """
+    Checks if the event was explicitly marked as experimental.
+    """
+    with configure_scope() as scope:
+        if scope._tags.get(EXPERIMENT_TAG):
+            return True
+    return False
+
+
 def mark_scope_as_unsafe():
     """
     Set the unsafe tag on the SDK scope for outgoing crashes and transactions.
@@ -148,6 +160,16 @@ def mark_scope_as_unsafe():
         scope.set_tag(UNSAFE_TAG, True)
 
 
+def mark_scope_as_experimental():
+    """
+    Set the experimental tag on the SDK scope for outgoing crashes and transactions.
+
+    Marking the scope will cause these crashes and transaction to be sent to a separate experimental dsn.
+    """
+    with configure_scope() as scope:
+        scope.set_tag(EXPERIMENT_TAG, True)
+
+
 def set_current_event_project(project_id):
     """
     Set the current project on the SDK scope for outgoing crash reports.
@@ -249,6 +271,7 @@ def configure_sdk():
     sdk_options = dict(settings.SENTRY_SDK_CONFIG)
 
     relay_dsn = sdk_options.pop("relay_dsn", None)
+    experimental_dsn = sdk_options.pop("experimental_dsn", None)
     internal_project_key = get_project_key()
     upstream_dsn = sdk_options.pop("dsn", None)
     sdk_options["traces_sampler"] = traces_sampler
@@ -274,6 +297,12 @@ def configure_sdk():
     else:
         relay_transport = None
 
+    if experimental_dsn:
+        transport = make_transport(get_options(dsn=experimental_dsn, **sdk_options))
+        experimental_transport = patch_transport_for_instrumentation(transport, "experimental")
+    else:
+        experimental_transport = None
+
     class MultiplexingTransport(sentry_sdk.transport.Transport):
         def capture_envelope(self, envelope):
             # Temporarily capture envelope counts to compare to ingested
@@ -299,6 +328,14 @@ def capture_event(self, event):
             self._capture_anything("capture_event", event)
 
         def _capture_anything(self, method_name, *args, **kwargs):
+            # Experimental events will be sent to the experimental transport.
+            if experimental_transport:
+                rate = options.get("store.use-experimental-dsn-sample-rate")
+                if is_current_event_experimental():
+                    if rate and random.random() < rate:
+                        getattr(experimental_transport, method_name)(*args, **kwargs)
+                    # Experimental events should not be sent to other transports even if they are not sampled.
+                    return
 
             # Upstream should get the event first because it is most isolated from
             # the this sentry installation.