From ee4a8e593dbc95b0a83cb42897640a405460ea7a Mon Sep 17 00:00:00 2001
From: kireetb <bhat.kireet@gmail.com>
Date: Mon, 3 Feb 2025 22:50:58 -0500
Subject: [PATCH] simpler custom spawn bucket sizes for prometheus

---
 docs/source/reference/monitoring.md | 10 +++++++++
 jupyterhub/metrics.py               | 32 +++++++----------------------
 2 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/docs/source/reference/monitoring.md b/docs/source/reference/monitoring.md
index 622f52aa..8208d799 100644
--- a/docs/source/reference/monitoring.md
+++ b/docs/source/reference/monitoring.md
@@ -33,6 +33,16 @@ export JUPYTERHUB_METRICS_PREFIX=jupyterhub_prod
 
 would result in the metric `jupyterhub_prod_active_users`, etc.
 
+## Customizing spawn bucket sizes
+
+As of JupyterHub >= 5.2.1, override `JUPYTERHUB_SERVER_SPAWN_DURATION_SECONDS_BUCKETS` env variable in Hub's environment to allow custom bucket sizes. Otherwise default to, [0.5, 1, 2.5, 5, 10, 15, 30, 60, 120, 180, 300, 600, float("inf")]
+
+For example,
+
+```bash
+export JUPYTERHUB_SERVER_SPAWN_DURATION_SECONDS_BUCKETS="1,2,4,6,12,30,60,120"
+```
+
 ## Configuring metrics
 
 ```{eval-rst}
diff --git a/jupyterhub/metrics.py b/jupyterhub/metrics.py
index adf6efd1..90bb41d4 100644
--- a/jupyterhub/metrics.py
+++ b/jupyterhub/metrics.py
@@ -36,31 +36,13 @@ from traitlets.config import LoggingConfigurable
 from . import orm
 from .utils import utcnow
 
+metrics_prefix = os.getenv('JUPYTERHUB_METRICS_PREFIX', 'jupyterhub')
+_env_buckets = os.environ.get('JUPYTERHUB_SERVER_SPAWN_DURATION_SECONDS_BUCKETS', "").strip()
 
-class CustomEnvVars(HasTraits):
-    bucket_sizes = List().tag(config=True)
-    metrics_prefix = os.getenv('JUPYTERHUB_METRICS_PREFIX', 'jupyterhub')
-
-    def load_from_env(self):
-        env_var_bucket_sizes = os.getenv(
-            'JUPYTERHUB_SERVER_SPAWN_DURATION_SECONDS_BUCKET_SIZES',
-            '[0.5, 1, 2.5, 5, 10, 15, 30, 60, 120, 180, 300, 600]',
-        )
-
-        try:
-            # Manually convert the string to a list
-            # Here we assume the string is in the format '[1, 2, 3]'
-            cleaned = env_var_bucket_sizes.strip('[]').replace(' ', '')
-            self.bucket_sizes = [str(i) for i in cleaned.split(',')]
-        except (ValueError, AttributeError):
-            # Handle if conversion fails
-            raise TraitError("Failed to convert environment variable to list.")
-
-
-custom_env = CustomEnvVars()
-custom_env.load_from_env()
-metrics_prefix = custom_env.metrics_prefix
-bucket_sizes = custom_env.bucket_sizes
+if _env_buckets:
+    spawn_duration_buckets = [float(_s) for _s in _env_buckets.split(",")]
+else:
+    spawn_duration_buckets = [0.5, 1, 2.5, 5, 10, 15, 30, 60, 120, 180, 300, 600, float("inf")]
 
 REQUEST_DURATION_SECONDS = Histogram(
     'request_duration_seconds',
@@ -75,7 +57,7 @@ SERVER_SPAWN_DURATION_SECONDS = Histogram(
     ['status'],
     # Use custom bucket sizes, since the default bucket ranges
     # are meant for quick running processes. Spawns can take a while!
-    buckets=bucket_sizes,
+    buckets=spawn_duration_buckets,
     namespace=metrics_prefix,
 )