Add a traitlet to disable recording HTTP request metrics (#1472)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Zachary Sailer <zachsailer@gmail.com>

Author: 3 people

jupyter_server/log.py

@@ -41,13 +41,16 @@ def _scrub_uri(uri: str) -> str:
     return uri
 
 
-def log_request(handler):
+def log_request(handler, record_prometheus_metrics=True):
     """log a bit more information about each request than tornado's default
 
     - move static file get success to debug-level (reduces noise)
     - get proxied IP instead of proxy IP
     - log referer for redirect and failed requests
     - log user-agent for failed requests
+
+    if record_prometheus_metrics is true, will record a histogram prometheus
+    metric (http_request_duration_seconds) for each request handler
     """
     status = handler.get_status()
     request = handler.request
@@ -97,4 +100,5 @@ def log_request(handler):
                 headers[header] = request.headers[header]
         log_method(json.dumps(headers, indent=2))
     log_method(msg.format(**ns))
-    prometheus_log_method(handler)
+    if record_prometheus_metrics:
+        prometheus_log_method(handler)

jupyter_server/serverapp.py

@@ -28,6 +28,7 @@
 import urllib
 import warnings
 from base64 import encodebytes
+from functools import partial
 from pathlib import Path
 
 import jupyter_client
@@ -410,7 +411,9 @@ def init_settings(
 
         settings = {
             # basics
-            "log_function": log_request,
+            "log_function": partial(
+                log_request, record_prometheus_metrics=jupyter_app.record_http_request_metrics
+            ),
             "base_url": base_url,
             "default_url": default_url,
             "template_path": template_path,
@@ -1993,6 +1996,18 @@ def _default_terminals_enabled(self) -> bool:
         config=True,
     )
 
+    record_http_request_metrics = Bool(
+        True,
+        help="""
+        Record http_request_duration_seconds metric in the metrics endpoint.
+
+        Since a histogram is exposed for each request handler, this can create a
+        *lot* of metrics, creating operational challenges for multitenant deployments.
+
+        Set to False to disable recording the http_request_duration_seconds metric.
+        """,
+    )
+
     static_immutable_cache = List(
         Unicode(),
         help="""