add metrics_authentication decorator to /metrics API

jupyterhub/app.py

@@ -618,6 +618,9 @@ class JupyterHub(Application):
         """
     ).tag(config=True)
 
+    authenticate_prometheus = Bool(True,
+        help="Authentication for prometheus metrics").tag(config=True)
+
     @observe('api_tokens')
     def _deprecate_api_tokens(self, change):
         self.log.warning("JupyterHub.api_tokens is pending deprecation"
@@ -1621,6 +1624,7 @@ class JupyterHub(Application):
             concurrent_spawn_limit=self.concurrent_spawn_limit,
             spawn_throttle_retry_range=self.spawn_throttle_retry_range,
             active_server_limit=self.active_server_limit,
+            authenticate_prometheus=self.authenticate_prometheus
         )
         # allow configured settings to have priority
         settings.update(self.tornado_settings)

jupyterhub/handlers/base.py

@@ -206,6 +206,10 @@ class BaseHandler(RequestHandler):
     def redirect_to_server(self):
         return self.settings.get('redirect_to_server', True)
 
+    @property
+    def authenticate_prometheus(self):
+        return self.settings.get('authenticate_prometheus', True)
+
     def get_auth_token(self):
         """Get the authorization token from Authorization header"""
         auth_header = self.request.headers.get('Authorization', '')

jupyterhub/handlers/metrics.py

@@ -2,11 +2,13 @@ from prometheus_client import REGISTRY, CONTENT_TYPE_LATEST, generate_latest
 from tornado import gen
 
 from .base import BaseHandler
+from ..utils import metrics_authentication
 
 class MetricsHandler(BaseHandler):
     """
     Handler to serve Prometheus metrics
     """
+    @metrics_authentication
     async def get(self):
         self.set_header('Content-Type', CONTENT_TYPE_LATEST)
         self.write(generate_latest(REGISTRY))

jupyterhub/utils.py

@@ -247,6 +247,14 @@ def admin_only(self):
     if user is None or not user.admin:
         raise web.HTTPError(403)
 
+@auth_decorator
+def metrics_authentication(self):
+    """Decorator for restricting access to metrics"""
+    user = self.get_current_user()
+    authenticate_prometheus = self.authenticate_prometheus()
+    if user is None and not user.authenticate_prometheus:
+        raise web.HTTPError(403)
+
 
 # Token utilities