Add ability to configure traits via envs

Author: kevin-bates

jupyter_server/services/kernelspecs/kernelspec_cache.py

@@ -51,13 +51,15 @@ def _cache_enabled_default(self):
 
     kernel_spec_manager = Instance("jupyter_client.kernelspec.KernelSpecManager")
 
+    monitor_name_env = "JUPYTER_KERNELSPEC_MONITOR_NAME"
     monitor_name = Unicode(
-        help="""The name of the entry_point used to monitor changes to kernelspecs.""",
+        help="""The name of the entry_point used to monitor changes to kernelspecs.
+(JUPYTER_KERNELSPEC_MONITOR_NAME env var)""",
     ).tag(config=True)
 
     @default("monitor_name")
     def _monitor_name_default(self):
-        return "polling-monitor"
+        return os.getenv(self.monitor_name_env, "polling-monitor")
 
     # The kernelspec cache consists of a dictionary mapping the kernel name to the actual
     # kernelspec data (CacheItemType).

jupyter_server/services/kernelspecs/monitors/polling_monitor.py

@@ -1,25 +1,30 @@
 """KernelSpec watchdog monitor used by KernelspecCache."""
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-
 import json
+import os
 from hashlib import md5
 
 from overrides import overrides
-from traitlets.traitlets import Float
+from traitlets.traitlets import Float, default
 
 from ..kernelspec_cache import KernelSpecCache, KernelSpecMonitorBase
 
 
 class KernelSpecPollingMonitor(KernelSpecMonitorBase):
     """Polling monitor that uses a periodic poll period to reload the kernelspec cache."""
 
+    interval_env = "JUPYTER_POLLING_MONITOR_INTERVAL"
     interval = Float(
-        default_value=30.0,
         config=True,
-        help="""The interval (in seconds) at which kernelspecs are updated in the cache.""",
+        help="""The interval (in seconds) at which kernelspecs are updated in the cache.
+(JUPYTER_POLLING_MONITOR_INTERVAL env var)""",
     )
 
+    @default("interval")
+    def _interval_default(self):
+        return float(os.getenv(self.interval_env, "30.0"))
+
     _pcallback = None
 
     # Keep track of hash values for each entry placed into the cache.  This will lessen