User Quota System

The quota system manages and tracks resource usage for JupyterHub users. It enables administrators to allocate, monitor, and control how much compute time users can consume.

Overview

Key Concepts

  • Balance: The amount of quota credits a user has available

  • Rate: The cost per minute for different resource types (CPU, GPU, NPU)

  • Session: A tracked period of container usage that consumes quota

  • Unlimited Quota: Special status exempting users from quota deductions

How It Works

  1. User requests to start a container

  2. System checks if user has sufficient quota for the estimated runtime

  3. If sufficient, a usage session begins tracking time

  4. When container stops, actual usage is calculated and quota is deducted

  5. Formula: quota_consumed = rate × duration_minutes

Configuration

Configure the quota system in your Helm values.yaml under custom.quota:

custom:
  quota:
    enabled: null              # Enable/disable quota system (null = auto-detect based on authMode)
    cpuRate: 1                 # Cost per minute for CPU-only containers
    minimumToStart: 10         # Minimum quota required to start any container
    defaultQuota: 0            # Default quota granted to new users (0 = no initial allocation)

New User Default Quota

The defaultQuota setting controls how much quota new users receive automatically:

  • Value 0 (default): New users start with zero quota and must be manually granted quota by an administrator

  • Value > 0: New users are automatically granted this amount when they first attempt to use the system

Example configuration:

custom:
  quota:
    defaultQuota: 100  # Automatically grant 100 quota units to new users

How It Works

This automatic allocation happens when a new user first tries to start a container. The system will:

  1. Check if the user has a quota record in the database

  2. If not found and defaultQuota > 0, create a record with the default amount

  3. Record this as an “initial_grant” transaction in the audit log

Unlimited Quota

Unlimited quota status is managed via the Admin UI. To grant unlimited quota to a user:

  1. Go to the Admin Panel (/hub/admin/users)

  2. Click on the user’s quota value

  3. Enter -1, ∞, or unlimited in the input field

  4. Click Save

Quota Rates by Resource Type

Each accelerator type can have a different quota rate defined in custom.accelerators:

custom:
  accelerators:
    phx:
      quotaRate: 2          # Phoenix iGPU: 2 quota/minute
    strix:
      quotaRate: 2          # Strix iGPU: 2 quota/minute
    strix-halo:
      quotaRate: 3          # Strix Halo iGPU: 3 quota/minute
    dgpu:
      quotaRate: 4          # Discrete GPU: 4 quota/minute
    strix-npu:
      quotaRate: 1          # NPU: 1 quota/minute

Auto-Enable Behavior

The quota system is automatically enabled/disabled based on authentication mode:

  • Enabled: github, multi authentication modes

  • Disabled: auto-login, dummy modes (typically for development)

Scheduled Quota Refresh (CronJob)

You can configure automatic quota refresh rules that run on a schedule. Each rule creates a Kubernetes CronJob.

Basic Setup

Add refresh rules to your values.yaml:

custom:
  quota:
    refreshRules:
      daily-topup:
        enabled: true
        schedule: "0 0 * * *"       # Every day at midnight
        action: add                  # add or set
        amount: 100                  # Add 100 quota daily
        maxBalance: 500              # Cap balance at 500
        targets:
          includeUnlimited: false    # Skip unlimited users

Configuration Options

Field

Type

Description

enabled

bool

Enable/disable this rule

schedule

string

Cron expression (e.g., "0 0 * * *" = daily at midnight)

action

string

add (default) or set

amount

int

Quota amount (positive to add, negative to deduct)

maxBalance

int

Maximum balance cap (for add action)

minBalance

int

Minimum balance floor (prevents going negative)

targets

object

Targeting rules (see below)

Targeting Options

Filter which users are affected:

Target

Type

Description

includeUnlimited

bool

Include users with unlimited quota

balanceBelow

int

Only users with balance below this value

balanceAbove

int

Only users with balance above this value

includeUsers

list

Only these specific usernames

excludeUsers

list

Exclude these usernames

usernamePattern

string

Regex pattern (e.g., "^student_.*")

Example Rules

custom:
  quota:
    refreshRules:
      # Daily top-up: Add 100 to users below 400
      daily-topup:
        enabled: true
        schedule: "0 0 * * *"
        action: add
        amount: 100
        maxBalance: 500
        targets:
          includeUnlimited: false
          balanceBelow: 400

      # Monthly reset: Set everyone to 500
      monthly-reset:
        enabled: true
        schedule: "0 0 1 * *"        # 1st of each month
        action: set
        amount: 500
        targets:
          includeUnlimited: false

      # Weekly decay: Deduct 50 from users above 100
      weekly-decay:
        enabled: false
        schedule: "0 0 * * 0"        # Every Sunday
        amount: -50
        minBalance: 0
        targets:
          balanceAbove: 100

Cron Schedule Syntax

┌───────────── minute (0-59)
│ ┌───────────── hour (0-23)
│ │ ┌───────────── day of month (1-31)
│ │ │ ┌───────────── month (1-12)
│ │ │ │ ┌───────────── day of week (0-6, Sun=0)
│ │ │ │ │
* * * * *

Common examples:

  • "0 0 * * *" - Daily at midnight

  • "0 8 * * 1-5" - Weekdays at 8:00 AM

  • "0 0 1 * *" - 1st of each month at midnight

  • "0 0 * * 0" - Every Sunday at midnight

  • "*/30 * * * *" - Every 30 minutes

Verify CronJobs

After helm upgrade, check if CronJobs are created:

# List quota refresh CronJobs
kubectl -n jupyterhub get cronjobs -l app.kubernetes.io/component=quota-refresh

# Check recent job runs
kubectl -n jupyterhub get jobs -l app.kubernetes.io/component=quota-refresh

# View logs from last run
kubectl -n jupyterhub logs -l app.kubernetes.io/component=quota-refresh --tail=50

Admin Operations

Web Interface (Admin Panel)

The Admin Panel provides a graphical interface for quota management. Access it at /hub/admin/users.

Users Page with Quota

Quota Column

When the quota system is enabled, the Users page displays a Quota column showing each user’s balance.

Inline Editing

Click directly on a user’s quota value to edit:

  • Enter a new number and press Enter to save

  • Press Escape to cancel

  • Enter -1, ∞, or unlimited to grant unlimited status

Inline Quota Editing

Batch Operations

  1. Select multiple users using checkboxes

  2. Click “Set Quota” button (appears when users are selected)

Batch Select Users

  1. Enter the quota value:

    • A number (e.g., 500) to set exact balance

    • -1, ∞, or unlimited to grant unlimited status

  2. Click “Apply” to update all selected users

Batch Quota Modal

REST API Endpoints

All admin endpoints require authentication. Admin-specific operations require admin privileges.

List All User Quotas

GET /admin/api/quota/

Response:

{
  "users": [
    {"username": "user1", "balance": 500, "unlimited": false, "updated_at": "2026-01-15T10:00:00"},
    {"username": "user2", "balance": 1000, "unlimited": true, "updated_at": "2026-01-15T09:30:00"}
  ]
}

Get Single User Quota

GET /admin/api/quota/<username>

Response:

{
  "username": "user1",
  "balance": 500,
  "unlimited": false,
  "recent_transactions": [
    {
      "id": 123,
      "username": "user1",
      "amount": -10,
      "transaction_type": "usage",
      "resource_type": "cpu",
      "description": "Session 456: 10 minutes",
      "balance_before": 510,
      "balance_after": 500,
      "created_at": "2026-01-15T10:00:00",
      "created_by": null
    }
  ]
}

Modify User Quota

POST /admin/api/quota/<username>
Content-Type: application/json

{
  "action": "set",
  "amount": 100,
  "unlimited": true,
  "description": "Monthly allocation"
}

  • action: "set", "add", "deduct", or "set_unlimited"

  • amount: Required for set/add/deduct

  • unlimited: Required for set_unlimited

Actions:

  • set: Set balance to exact amount

  • add: Add amount to current balance

  • deduct: Subtract amount from balance

  • set_unlimited: Mark/unmark user as having unlimited quota

Response:

{
  "username": "user1",
  "balance": 100,
  "action": "set",
  "amount": 100
}

Batch Set Quota

POST /admin/api/quota/batch
Content-Type: application/json

{
  "users": [
    {"username": "user1", "amount": 100},
    {"username": "user2", "amount": 200}
  ]
}

Response:

{
  "success": 2,
  "failed": 0,
  "details": [
    {"username": "user1", "status": "success", "balance": 100},
    {"username": "user2", "status": "success", "balance": 200}
  ]
}

Batch Refresh Quota

Flexible batch operation with targeting rules:

POST /admin/api/quota/refresh
Content-Type: application/json

{
  "rule_name": "weekly_reset",
  "action": "add",
  "amount": 100,
  "max_balance": 1000,
  "min_balance": 0,
  "targets": {
    "includeUnlimited": false,
    "balanceBelow": 500,
    "balanceAbove": 0,
    "includeUsers": ["user1"],
    "excludeUsers": ["admin"],
    "usernamePattern": "^student_.*"
  }
}

Request fields:

  • action: "add" or "set"

  • max_balance: Optional cap for balance

  • min_balance: Optional floor for balance

Targeting Rules (AND logic):

  • includeUnlimited: Whether to include users marked as unlimited

  • balanceBelow: Only affect users with balance below this value

  • balanceAbove: Only affect users with balance above this value

  • includeUsers: Whitelist of specific usernames

  • excludeUsers: Blacklist of usernames to skip

  • usernamePattern: Regex pattern to match usernames

Response:

{
  "users_updated": 25,
  "total_change": 2500,
  "skipped": 5,
  "action": "add",
  "rule_name": "weekly_reset"
}

CLI Commands (manage_users.py)

The manage_users.py script provides command-line quota management via kubectl.

Set Quota

Set quota to a specific amount:

# Set quota for specific users
python scripts/manage_users.py set-quota user1 user2 --amount 1000

# Set quota from file (requires username column, optional quota column)
python scripts/manage_users.py set-quota -f users.csv --amount 500

# File with per-user amounts
python scripts/manage_users.py set-quota -f users_with_quota.csv

File format (users_with_quota.csv):

username,quota
student01,500
student02,1000
teacher01,2000

Add Quota

Add quota to existing balance:

# Add to specific users
python scripts/manage_users.py add-quota user1 user2 --amount 100

# Add to users from file
python scripts/manage_users.py add-quota -f users.csv --amount 50

List Quota Balances

Display all user quota balances:

python scripts/manage_users.py list-quota

Output:

📋 Quota Balances (25 users):

Username                  Balance         Last Updated
-----------------------------------------------------------------
student01                 450             2026-01-15 10:30:00
student02                 800             2026-01-15 09:15:00
teacher01                 1500            2026-01-14 16:45:00

User Experience

Viewing Personal Quota

Users can check their quota via the API:

GET /api/quota/me

Response:

{
  "username": "student01",
  "balance": 450,
  "unlimited": false,
  "rates": {"cpu": 1, "phx": 2, "strix": 2},
  "enabled": true
}

To get accelerator options, use the separate /api/accelerators endpoint.

Quota Rates API

Get quota rates and configuration (available to all authenticated users):

GET /api/quota/rates

Response:

{
  "enabled": true,
  "rates": {"cpu": 1, "phx": 2, "strix": 2},
  "minimum_to_start": 10
}

  • enabled: Whether the quota system is active

  • rates: Quota consumption rate per minute for each resource type

  • minimum_to_start: Minimum quota required to start any container

Accelerators API

Get available accelerator options (always available, independent of quota system):

GET /api/accelerators

Response:

{
  "accelerators": {
    "phx": {
      "displayName": "AMD Radeon™ 780M (Phoenix Point iGPU)",
      "description": "RDNA 3.0 (gfx1103) | Compute Units 12 | 4GB LPDDR5X",
      "nodeSelector": {"accelerator": "phx"},
      "quotaRate": 2
    }
  }
}

  • accelerators: Available accelerator options with display name, description, node selector, and quota rate

Insufficient Quota

When a user attempts to start a container without sufficient quota:

  1. System calculates estimated cost: rate × requested_runtime

  2. Compares with current balance and minimum requirement

  3. If insufficient, returns HTTP 403 error with message:

Cannot start container: Insufficient quota. Current balance: 5,
estimated cost: 120 (2 quota/min × 60 min).
Please contact administrator to add quota.

Quota Deduction

Quota is deducted when a container stops:

  1. System records actual duration (minimum 1 minute)

  2. Calculates actual cost: rate × actual_duration_minutes

  3. Deducts from user balance

  4. Records transaction in audit log

Technical Details

Stale Session Cleanup

Sessions stuck for more than 8 hours are automatically cleaned up on hub startup:

  • Marks session as cleaned_up

  • Records duration but does NOT deduct quota (avoids charging for crashed sessions)

  • Logs cleanup for auditing

Unlimited Quota Logic

A user has unlimited quota if marked unlimited: true in the database.

Troubleshooting

User Cannot Start Container

Symptom: “Insufficient quota” error

Solutions:

  1. Check user’s current balance:

    python scripts/manage_users.py list-quota | grep username

  2. Add quota to user:

    python scripts/manage_users.py add-quota username --amount 500

  3. Or grant unlimited quota via Admin UI (click quota value and enter ∞)

Quota Not Being Deducted

Symptom: User’s balance doesn’t decrease after container use

Possible causes:

  1. User has unlimited quota (set via Admin UI)

  2. Quota system is disabled (custom.quota.enabled: false)

  3. Session ended abnormally (cleaned up as stale)

Check:

# View user's transaction history
curl "$JUPYTERHUB_URL/admin/api/quota/username" \
  -H "Authorization: token $JUPYTERHUB_TOKEN"

Session Stuck as Active

Symptom: Old sessions show as active even though containers stopped

Solution: Sessions are automatically cleaned on hub restart, or manually:

# Restart hub to trigger cleanup
kubectl -n jupyterhub rollout restart deployment/hub

Database Issues

Location: /srv/jupyterhub/quota.sqlite (inside hub pod)

Access for debugging:

kubectl -n jupyterhub exec deployment/hub -- sqlite3 /srv/jupyterhub/quota.sqlite \
  "SELECT * FROM user_quota LIMIT 10;"

See Also