Jupyter Server

Warnings

• breaking Migrating from Jupyter Notebook (pre-7) to Jupyter Server (v2+) involves significant breaking changes. Configuration files moved from `jupyter_notebook_config.py` to `jupyter_server_config.py`, and server-related imports from the `notebook` package should be updated to `jupyter_server`.
  Fix: Migrate `jupyter_notebook_config.py|json` to `jupyter_server_config.py|json`, changing `c.NotebookApp` references to `c.ServerApp`. Update import paths from `from notebook.x import Y` to `from jupyter_server.x import Y`. Specifically, `ServerApp.preferred_dir` is deprecated; use `FileContentsManager.preferred_dir` instead.
• gotcha Jupyter Server defaults to token-based authentication for security. If you try to access the server without a token or a configured password, you will be prompted for authentication. Direct password login is not enabled by default when token authentication is active.
  Fix: When starting, note the token printed in the console and use it in the URL (`?token=your_token`). For persistent password authentication, use `jupyter server password` to set a hashed password or configure it in `jupyter_server_config.py`.
• gotcha Mismatches between the Python environment where Jupyter Server is running and the environment where kernels are sourced can lead to `ImportError` or `ModuleNotFound` exceptions within notebooks.
  Fix: Ensure that the desired Python packages and kernel environments are correctly installed and accessible by the Jupyter Server. Use `jupyter kernelspec list` to verify available kernels and their paths. Often, installing packages into the same environment where `jupyter_server` is installed resolves this.
• gotcha Jupyter Server (and its kernels) can crash due to excessive memory usage, often caused by very large datasets, long-running computations, or extensive cell outputs.
  Fix: Monitor memory usage. For large datasets, consider processing in chunks. For persistent issues, you may need to adjust Jupyter's configuration, such as `c.ServerApp.max_buffer_size` in `jupyter_server_config.py`, or allocate more system resources.
• gotcha For remote access or specific deployments, firewall configuration is essential. The server's main port (`ServerApp.port`) must be open, as well as a range of ephemeral ports (typically 49152 to 65535) used by ZeroMQ for kernel communication.
  Fix: Configure your firewall to allow TCP connections on the specified server port and the ephemeral port range (49152-65535). Consult your operating system or cloud provider's firewall documentation.

Install

• pip install jupyter_server Install latest version

Imports

• ServerApp

  from jupyter_server.serverapp import ServerApp

• ExtensionApp

  from jupyter_server.extension.application import ExtensionApp

  Used for developing Jupyter Server extensions.

Quickstart

The most common way to start Jupyter Server is via the command line with `jupyter server`. For programmatic control, the `ServerApp` can be initialized and started within a Python script. This example demonstrates a minimal programmatic startup, explicitly disabling browser opening and authentication for demonstration purposes. **For production use, it is critical to enable and properly configure authentication (tokens/passwords).**

import asyncio
import os
from jupyter_server.serverapp import ServerApp

async def start_jupyter_server():
    # Instantiate the server application
    # For a quickstart, we disable browser opening and token/password for simplicity.
    # In production, ALWAYS secure your Jupyter Server with tokens/passwords.
    app = ServerApp(
        open_browser=False,
        port=os.environ.get("JUPYTER_SERVER_PORT", 8888),
        port_retries=0,
        token="", # IMPORTANT: Do NOT use empty token in production.
        password="" # IMPORTANT: Do NOT use empty password in production.
    )
    
    await app.initialize()
    await app.start()

    print(f"Jupyter Server running at: {app.url} (Access via web browser if not using --no-browser, use the printed URL including token if applicable)")
    print("Press Ctrl+C to stop the server.")

    try:
        # Keep the server running until interrupted
        await asyncio.Event().wait()
    except KeyboardInterrupt:
        print("\nServer stopping...")
    finally:
        await app.stop()

if __name__ == "__main__":
    # To run this, save as a Python file (e.g., `run_server.py`) and execute `python run_server.py`.
    # Alternatively, for a basic command-line start, simply run `jupyter server` in your terminal.
    asyncio.run(start_jupyter_server())