Sentry: Add trace tokens

doc/admin/config.rst

@@ -351,6 +351,7 @@ application. If you want to use sentry, you need to set a DSN in the configurati
     [sentry]
     dsn=https://<key>:<secret>@sentry.io/<project>
     traces_sample_rate=0.5
+    traces_sample_token=xyz
 
 ``dsn``
     You will be given this value by your sentry installation.
@@ -358,6 +359,9 @@ application. If you want to use sentry, you need to set a DSN in the configurati
 ``traces_sample_rate``
     Sample rate for performance monitoring.
 
+``traces_sample_token``
+    If this token is found in a query string, a trace will always be sampled.
+
 
 Caching
 -------

src/pretix/settings.py

@@ -712,6 +712,14 @@ if config.has_option('sentry', 'dsn') and not any(c in sys.argv for c in ('shell
 
     from .sentry import PretixSentryIntegration, setup_custom_filters
 
+    SENTRY_TOKEN = config.get('sentry', 'traces_sample_token', fallback='')
+
+    def traces_sampler(sampling_context):
+        qs = sampling_context.get('wsgi_environ', {}).get('QUERY_STRING', '')
+        if SENTRY_TOKEN and SENTRY_TOKEN in qs:
+            return 1.0
+        return config.getfloat('sentry', 'traces_sample_rate', fallback=0.0)
+
     SENTRY_ENABLED = True
     sentry_sdk.init(
         dsn=config.get('sentry', 'dsn'),
@@ -723,7 +731,7 @@ if config.has_option('sentry', 'dsn') and not any(c in sys.argv for c in ('shell
                 event_level=logging.CRITICAL
             )
         ],
-        traces_sample_rate=config.getfloat('sentry', 'traces_sample_rate', fallback=0.0),
+        traces_sampler=traces_sampler,
         environment=urlparse(SITE_URL).netloc,
         release=__version__,
         send_default_pii=False,