Enable tracing without performance by default (#4240)

Changing the default of `traces_sample_rate` to `0`. This means incoming
traces will be continued, but we will not start traces on our own. (It
used to be set to: never start or continue traces by default)

Refs #4102

Author: antonpirker

MIGRATION_GUIDE.md

@@ -9,6 +9,7 @@ Looking to upgrade from Sentry SDK 2.x to 3.x? Here's a comprehensive list of wh
 ### Changed
 
 - The SDK now supports Python 3.7 and higher.
+- The default of `traces_sample_rate` changed to `0`. Meaning: Incoming traces will be continued by default. For example, if your frontend sends a `sentry-trace/baggage` headers pair, your SDK will create Spans and send them to Sentry. (The default used to be `None` meaning by default no Spans where created, no matter what headers the frontend sent to your project.) See also: https://docs.sentry.io/platforms/python/configuration/options/#traces_sample_rate
 - `sentry_sdk.start_span` now only takes keyword arguments.
 - `sentry_sdk.start_transaction`/`sentry_sdk.start_span` no longer takes the following arguments: `span`, `parent_sampled`, `trace_id`, `span_id` or `parent_span_id`.
 - You can no longer change the sampled status of a span with `span.sampled = False` after starting it.

sentry_sdk/consts.py

@@ -511,7 +511,7 @@ def __init__(
         debug=None,  # type: Optional[bool]
         attach_stacktrace=False,  # type: bool
         ca_certs=None,  # type: Optional[str]
-        traces_sample_rate=None,  # type: Optional[float]
+        traces_sample_rate=0,  # type: Optional[float]
         traces_sampler=None,  # type: Optional[TracesSampler]
         profiles_sample_rate=None,  # type: Optional[float]
         profiles_sampler=None,  # type: Optional[TracesSampler]

tests/integrations/aiohttp/test_aiohttp.py

@@ -448,7 +448,10 @@ async def hello(request):
 async def test_trace_from_headers_if_performance_disabled(
     sentry_init, aiohttp_client, capture_events
 ):
-    sentry_init(integrations=[AioHttpIntegration()])
+    sentry_init(
+        integrations=[AioHttpIntegration()],
+        traces_sample_rate=None,  # disable all performance monitoring
+    )
 
     async def hello(request):
         capture_message("It's a good day to try dividing by 0")

tests/integrations/asgi/test_asgi.py

@@ -269,7 +269,9 @@ async def test_has_trace_if_performance_disabled(
     asgi3_app_with_error_and_msg,
     capture_events,
 ):
-    sentry_init()
+    sentry_init(
+        traces_sample_rate=None,  # disable all performance monitoring
+    )
     app = SentryAsgiMiddleware(asgi3_app_with_error_and_msg)
 
     with pytest.raises(ZeroDivisionError):
@@ -325,7 +327,9 @@ async def test_trace_from_headers_if_performance_disabled(
     asgi3_app_with_error_and_msg,
     capture_events,
 ):
-    sentry_init()
+    sentry_init(
+        traces_sample_rate=None,  # disable all performance monitoring
+    )
     app = SentryAsgiMiddleware(asgi3_app_with_error_and_msg)
 
     trace_id = "582b43a4192642f0b136d5159a501701"

tests/integrations/django/asgi/test_asgi.py

@@ -321,6 +321,7 @@ async def test_has_trace_if_performance_enabled(sentry_init, capture_events):
 async def test_has_trace_if_performance_disabled(sentry_init, capture_events):
     sentry_init(
         integrations=[DjangoIntegration()],
+        traces_sample_rate=None,  # disable all performance monitoring
     )
 
     events = capture_events()
@@ -386,6 +387,7 @@ async def test_trace_from_headers_if_performance_enabled(sentry_init, capture_ev
 async def test_trace_from_headers_if_performance_disabled(sentry_init, capture_events):
     sentry_init(
         integrations=[DjangoIntegration()],
+        traces_sample_rate=None,  # disable all performance monitoring
     )
 
     events = capture_events()

tests/integrations/django/test_basic.py

@@ -241,6 +241,7 @@ def test_trace_from_headers_if_performance_disabled(
                 http_methods_to_capture=("HEAD",),
             )
         ],
+        traces_sample_rate=None,  # disable all performance monitoring
     )
 
     events = capture_events()

tests/integrations/opentelemetry/test_sampler.py

@@ -6,14 +6,16 @@
 import sentry_sdk
 
 
+USE_DEFAULT_TRACES_SAMPLE_RATE = -1
+
 tracer = trace.get_tracer(__name__)
 
 
 @pytest.mark.parametrize(
     "traces_sample_rate, expected_num_of_envelopes",
     [
-        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=None will be used)
-        (-1, 0),
+        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=0 will be used)
+        (USE_DEFAULT_TRACES_SAMPLE_RATE, 0),
         # traces_sample_rate=None means do not create new traces, and also do not continue incoming traces. So, no envelopes at all.
         (None, 0),
         # traces_sample_rate=0 means do not create new traces (0% of the requests), but continue incoming traces. So envelopes will be created only if there is an incoming trace.
@@ -29,7 +31,7 @@ def test_sampling_traces_sample_rate_0_or_100(
     expected_num_of_envelopes,
 ):
     kwargs = {}
-    if traces_sample_rate != -1:
+    if traces_sample_rate != USE_DEFAULT_TRACES_SAMPLE_RATE:
         kwargs["traces_sample_rate"] = traces_sample_rate
 
     sentry_init(**kwargs)
@@ -176,8 +178,8 @@ def keep_only_a(sampling_context):
 @pytest.mark.parametrize(
     "traces_sample_rate, expected_num_of_envelopes",
     [
-        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=None will be used)
-        (-1, 0),
+        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=0 will be used)
+        (USE_DEFAULT_TRACES_SAMPLE_RATE, 1),
         # traces_sample_rate=None means do not create new traces, and also do not continue incoming traces. So, no envelopes at all.
         (None, 0),
         # traces_sample_rate=0 means do not create new traces (0% of the requests), but continue incoming traces. So envelopes will be created only if there is an incoming trace.
@@ -193,7 +195,7 @@ def test_sampling_parent_sampled(
     capture_envelopes,
 ):
     kwargs = {}
-    if traces_sample_rate != -1:
+    if traces_sample_rate != USE_DEFAULT_TRACES_SAMPLE_RATE:
         kwargs["traces_sample_rate"] = traces_sample_rate
 
     sentry_init(**kwargs)
@@ -227,9 +229,11 @@ def test_sampling_parent_sampled(
 @pytest.mark.parametrize(
     "traces_sample_rate, upstream_sampled, expected_num_of_envelopes",
     [
-        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=None will be used)
-        (-1, 0, 0),
+        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=0 will be used)
+        (USE_DEFAULT_TRACES_SAMPLE_RATE, 0, 0),
+        (USE_DEFAULT_TRACES_SAMPLE_RATE, 1, 1),
         # traces_sample_rate=None means do not create new traces, and also do not continue incoming traces. So, no envelopes at all.
+        (None, 0, 0),
         (None, 1, 0),
         # traces_sample_rate=0 means do not create new traces (0% of the requests), but continue incoming traces. So envelopes will be created only if there is an incoming trace.
         (0, 0, 0),
@@ -247,7 +251,7 @@ def test_sampling_parent_dropped(
     capture_envelopes,
 ):
     kwargs = {}
-    if traces_sample_rate != -1:
+    if traces_sample_rate != USE_DEFAULT_TRACES_SAMPLE_RATE:
         kwargs["traces_sample_rate"] = traces_sample_rate
 
     sentry_init(**kwargs)
@@ -281,8 +285,8 @@ def test_sampling_parent_dropped(
 @pytest.mark.parametrize(
     "traces_sample_rate, expected_num_of_envelopes",
     [
-        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=None will be used)
-        (-1, 0),
+        # special case for testing, do not pass any traces_sample_rate to init() (the default traces_sample_rate=0 will be used)
+        (USE_DEFAULT_TRACES_SAMPLE_RATE, 0),
         # traces_sample_rate=None means do not create new traces, and also do not continue incoming traces. So, no envelopes at all.
         (None, 0),
         # traces_sample_rate=0 means do not create new traces (0% of the requests), but continue incoming traces. So envelopes will be created only if there is an incoming trace.
@@ -298,7 +302,7 @@ def test_sampling_parent_deferred(
     capture_envelopes,
 ):
     kwargs = {}
-    if traces_sample_rate != -1:
+    if traces_sample_rate != USE_DEFAULT_TRACES_SAMPLE_RATE:
         kwargs["traces_sample_rate"] = traces_sample_rate
 
     sentry_init(**kwargs)

tests/integrations/wsgi/test_wsgi.py

@@ -238,7 +238,9 @@ def dogpark(environ, start_response):
         capture_message("Attempting to fetch the ball")
         raise ValueError("Fetch aborted. The ball was not returned.")
 
-    sentry_init()
+    sentry_init(
+        traces_sample_rate=None,  # disable all performance monitoring
+    )
     app = SentryWsgiMiddleware(dogpark)
     client = Client(app)
     events = capture_events()
@@ -301,7 +303,9 @@ def dogpark(environ, start_response):
         capture_message("Attempting to fetch the ball")
         raise ValueError("Fetch aborted. The ball was not returned.")
 
-    sentry_init()
+    sentry_init(
+        traces_sample_rate=None,  # disable all performance monitoring
+    )
     app = SentryWsgiMiddleware(dogpark)
     client = Client(app)
     events = capture_events()

tests/test_dsc.py

@@ -287,8 +287,8 @@ def my_traces_sampler(sampling_context):
                 "local_traces_sampler_result": None,
                 "local_traces_sample_rate": None,
             },
-            None,  # expected_sample_rate
-            "tracing-disabled-no-transactions-should-be-sent",  # expected_sampled (traces_sample_rate=None disables all transaction creation)
+            1.0,  # expected_sample_rate
+            "true",  # expected_sampled
         ),
         (  # 6 traces_sampler overrides incoming  (traces_sample_rate not set)
             {

tests/tracing/test_sample_rand_propagation.py

@@ -18,7 +18,7 @@ def test_continue_trace_with_sample_rand(sentry_init):
     sentry_init()
 
     headers = {
-        "sentry-trace": "00000000000000000000000000000000-0000000000000000-0",
+        "sentry-trace": "771a43a4192642f0b136d5159a501700-1234567890abcdef-0",
         "baggage": "sentry-sample_rand=0.1,sentry-sample_rate=0.5",
     }
 
@@ -34,7 +34,7 @@ def test_continue_trace_missing_sample_rand(sentry_init):
     sentry_init()
 
     headers = {
-        "sentry-trace": "00000000000000000000000000000000-0000000000000000",
+        "sentry-trace": "771a43a4192642f0b136d5159a501700-1234567890abcdef",
         "baggage": "sentry-placeholder=asdf",
     }
 

tests/tracing/test_sampling.py

@@ -310,7 +310,10 @@ def test_records_lost_event_only_if_traces_sampler_enabled(
     sampled_output,
     expected_record_lost_event_calls,
 ):
-    sentry_init(traces_sampler=traces_sampler)
+    sentry_init(
+        traces_sample_rate=None,
+        traces_sampler=traces_sampler,
+    )
     record_lost_event_calls = capture_record_lost_event_calls()
 
     with start_span(name="dogpark") as span: