jupyterlab_notifications_extension

[!TIP] This extension is part of the stellars_jupyterlab_extensions metapackage. Install all Stellars extensions at once: pip install stellars_jupyterlab_extensions

JupyterLab extension for sending notifications using the native JupyterLab notification system. External systems and extensions send alerts and status updates that appear in JupyterLab's notification center.

This extension serves as the notification backbone for Stellars JupyterHub Platform for Data Science, allowing administrators to broadcast notification messages to all running JupyterLab servers.

Five notification types with distinct visual styling provide clear status communication:

Access via command palette for quick manual notification sending:

Interactive dialog with message input, type selection, auto-close timing, and action button options:

Key Features:

• REST API for external systems to POST notifications with authentication
• Command palette integration with interactive dialog
• Programmatic command API for extensions and automation
• Six notification types (default, info, success, warning, error, in-progress)
• Configurable auto-close with millisecond precision or manual dismiss
• Action buttons with optional JupyterLab command execution
• Dynamic time-ago indicator showing when each notification was generated
• Broadcast delivery via 30-second polling
• Immediate WebSocket push for instant display (--now / "immediate": true)
• In-memory queue cleared after delivery

Installation

pip install jupyterlab_notifications_extension

Requirements: JupyterLab >= 4.0.0

API Reference

POST /jupyterlab-notifications-extension/ingest

Send notifications to JupyterLab. Requires authentication via Authorization: token <TOKEN> header or ?token=<TOKEN> query parameter.

Token-free localhost ingest is opt-in and off by default: set the environment variable JUPYTERLAB_NOTIFICATIONS_ALLOW_UNAUTHENTICATED_LOCALHOST=1 on the server to let genuine loopback (127.0.0.1, ::1) requests skip authentication. It is disabled by default because a same-host reverse proxy makes every external client's address appear as 127.0.0.1, which would otherwise open ingest to unauthenticated callers.

Endpoint: POST /jupyterlab-notifications-extension/ingest

Request Body (application/json):

{
  "message": "Your notification message",
  "type": "info",
  "autoClose": 5000,
  "immediate": true,
  "actions": [
    {
      "label": "Click here",
      "caption": "Additional info",
      "displayType": "accent"
    }
  ]
}

Request Parameters:

Action Button Schema:

Note: Clicking any button dismisses the notification. If commandId is provided, the specified JupyterLab command executes before dismissal.

Response (200 OK):

{
  "success": true,
  "notification_id": "notif_1762549476180_1"
}

Error Responses:

• 400 Bad Request - Missing message field or invalid JSON
• 401 Unauthorized - Missing or invalid authentication token
• 500 Internal Server Error - Server-side processing error

Usage Examples

From JupyterLab Extensions

Send notifications programmatically from other extensions:

// Basic notification
await app.commands.execute('jupyterlab-notifications:send', {
  message: 'Operation complete'
});

// Custom type and auto-close
await app.commands.execute('jupyterlab-notifications:send', {
  message: 'Build finished successfully',
  type: 'success',
  autoClose: 3000
});

// With dismiss button
await app.commands.execute('jupyterlab-notifications:send', {
  message: 'Error processing data',
  type: 'error',
  autoClose: false,
  actions: [{ label: 'Dismiss', displayType: 'default' }]
});

// Action button that executes a JupyterLab command
await app.commands.execute('jupyterlab-notifications:send', {
  message: 'Help Available!',
  type: 'info',
  autoClose: false,
  actions: [
    {
      label: 'Open Help',
      commandId: 'iframe:open',
      args: { path: 'local:///welcome.html' },
      displayType: 'accent'
    }
  ]
});

CLI Tool

The jupyterlab-notify command is installed with the extension:

# Basic notification (auto-detects URL from running servers)
jupyterlab-notify -m "Deployment complete" -t success

# With explicit URL (e.g., JupyterHub)
jupyterlab-notify --url "http://127.0.0.1:8888/jupyterhub/user/alice" -m "Hello"

# Persistent warning (no auto-close)
jupyterlab-notify -m "System maintenance in 1 hour" -t warning --no-auto-close

# With dismiss button
jupyterlab-notify -m "Task complete" --action "Dismiss"

# Action button that executes a JupyterLab command
jupyterlab-notify -m "Help Available!" --action "Open Help" \
  --cmd "iframe:open" --command-args '{"path": "local:///welcome.html"}'

# Silent mode (notification center only, no toast)
jupyterlab-notify -m "Background task finished" --auto-close 0

# Immediate display (push now, don't wait for the next poll)
jupyterlab-notify -m "Deploy finished" --now

URL auto-detection: Queries jupyter server list --json to find running servers and constructs localhost URL. Falls back to JUPYTERHUB_SERVICE_PREFIX environment variable or localhost:8888.

--now: Pushes the notification instantly to any open JupyterLab tab via WebSocket instead of waiting up to 30 seconds for the next poll (see Immediate Delivery).

cURL

# Localhost - no authentication required
curl -X POST http://localhost:8888/jupyterlab-notifications-extension/ingest \
  -H "Content-Type: application/json" \
  -d '{"message": "Build completed", "type": "success"}'

# Localhost - warning that stays until dismissed
curl -X POST http://localhost:8888/jupyterlab-notifications-extension/ingest \
  -H "Content-Type: application/json" \
  -d '{"message": "System maintenance in 1 hour", "type": "warning", "autoClose": false}'

# Remote - requires authentication token
curl -X POST http://jupyterhub.example.com/user/alice/jupyterlab-notifications-extension/ingest \
  -H "Content-Type: application/json" \
  -H "Authorization: token YOUR_JUPYTER_TOKEN" \
  -d '{"message": "Deployment complete", "type": "info"}'

# Immediate display - push now instead of waiting for the next poll
curl -X POST http://localhost:8888/jupyterlab-notifications-extension/ingest \
  -H "Content-Type: application/json" \
  -d '{"message": "Deploy finished", "type": "success", "immediate": true}'

Immediate Delivery

By default a notification waits up to 30 seconds for the frontend's next poll before it appears. Setting immediate (REST/cURL) or passing --now (CLI) pushes it instantly to every open JupyterLab tab over a WebSocket, so it displays the moment it is sent.

• Transport: the frontend keeps a WebSocket open to /jupyterlab-notifications-extension/stream; the server pushes flagged notifications to all connected clients
• Push reaches every connected tab: unlike the poll, the immediate push is delivered to all currently-open tabs at once
• Poll is best-effort: the poll queue is a single-consumer destructive drain - the first tab to poll empties it for all tabs - so a tab whose socket is down at push time is not guaranteed to receive that notification via the poll; the push is an accelerator over a best-effort baseline, not a durable per-client queue
• Keepalive: the socket uses ping/pong to survive proxy idle timeouts (works behind JupyterHub)
• De-duplication: the frontend tracks notification IDs (bounded), so a notification arriving via both the push and the poll is displayed only once
• Reconnect: the socket reconnects with capped exponential backoff and gives up after a bounded number of attempts, degrading to poll-only

Time-Ago Indicator

Each notification displays a relative timestamp (e.g., just now, 5m ago, 2h ago, 3d ago) that updates every 10 seconds while the notification remains visible. Anything under a minute shows just now. The indicator appears below the message when no action buttons are present, or inline with the button bar when buttons exist. The notification center panel also shows time-ago for all listed notifications.

Architecture

Broadcast-only model - all notifications delivered to the JupyterLab server.

Flow: External system POSTs to /jupyterlab-notifications-extension/ingest -> Server queues in memory -> Frontend polls /jupyterlab-notifications-extension/notifications every 30 seconds -> Displays via JupyterLab notification manager -> Clears queue after fetch. Notifications flagged immediate are additionally pushed over a WebSocket (/jupyterlab-notifications-extension/stream) for instant display, deduplicated against the poll by notification ID.

Troubleshooting

Frontend installed but not working:

jupyter server extension list  # Verify server extension enabled

Server extension enabled but frontend missing:

jupyter labextension list  # Verify frontend extension installed

Notifications not appearing: Check browser console for polling errors or verify JupyterLab was restarted after installation.

Uninstall

pip uninstall jupyterlab_notifications_extension

Development

Setup

Requires NodeJS to build the extension. Uses jlpm (JupyterLab's pinned yarn) for package management.

# Install in development mode
python -m venv .venv
source .venv/bin/activate
pip install --editable ".[dev,test]"

# Link extension with JupyterLab
jupyter labextension develop . --overwrite
jupyter server extension enable jupyterlab_notifications_extension

# Build TypeScript
jlpm build

Development workflow

Run jlpm watch in one terminal to auto-rebuild on changes, and jupyter lab in another. Refresh browser after rebuilds to load changes.

jlpm watch           # Auto-rebuild on file changes
jupyter lab          # Run JupyterLab

Cleanup

jupyter server extension disable jupyterlab_notifications_extension
pip uninstall jupyterlab_notifications_extension
# Remove symlink: find via `jupyter labextension list`

Testing

Python tests (Pytest):

pip install -e ".[test]"
pytest -vv -r ap --cov jupyterlab_notifications_extension

Frontend tests (Jest):

jlpm test

Integration tests (Playwright/Galata): See ui-tests/README.md

Packaging

See RELEASE.md for release procedures.