Chapters: 
Jupyter

Guide to Exploration of Camelot Python Environment

A concise reference for inspecting and understanding the Python landscape on Camelot, including Jupyter Server’s REST API surface and module locations. 

TL;DR

jupyter server --ip=0.0.0.0 --no-browser 

tux@camelot:~$ jupyter server --ip=0.0.0.0 --no-browser
[I 2025-07-27 19:45:15.711 ServerApp] jupyter_lsp | extension was successfully linked.

Ansible on Jupyter

 

Prerequisites

  • Access to the camelot server via SSH (user: tux or jupyter).
  • Jupyter Server running locally on camelot port 8888
  • jq installed for JSON parsing (sudo dnf install -y jq).

1. Inspect Installed Python Packages

List all Jupyter-related and core packages: 

pip3 list | grep -E 'notebook|jupyter|jupyter_server|python'
tux@camelot:~$ pip3 list | grep -E 'notebook|jupyter|jupyter_server|python'
dbus-python               1.3.2
ipython                   8.36.0
jupyter_client            8.6.1
jupyter_core              5.7.2
jupyter-events            0.11.0
jupyter-lsp               2.2.5
jupyter_server            2.15.0
jupyter_server_terminals  0.5.3
jupyterlab                4.4.0
jupyterlab_pygments       0.3.0
jupyterlab_server         2.27.3
libvirt-python            11.0.0
notebook                  7.4.0
notebook_shim             0.2.4
python-augeas             1.1.0
python-dateutil           2.8.2
python-json-logger        2.0.4
python-linux-procfs       0.7.3
python-pam                2.0.2
systemd-python            235

 

2. Locate Package Source Directories

Find on-disk locations for key modules: 


tux@camelot:~$ python3 - <<'PYCODE'
import notebook, jupyter_server, os
print("notebook module at:      ", os.path.dirname(notebook.__file__))
print("jupyter_server module at: ", os.path.dirname(jupyter_server.__file__))
PYCODE
notebook module at:       /usr/lib/python3.13/site-packages/notebook
jupyter_server module at:  /usr/lib/python3.13/site-packages/jupyter_server

Use these paths when browsing source or grepping for specific code patterns.

3. Enumerate REST Endpoints via OpenAPI

Jupyter Server exposes a full OpenAPI spec at /openapi.json. To list all available routes: 

curl -s http://localhost:8888/openapi.json \
  | jq -r '.paths | keys[]' \
  | sort

This prints every API path (e.g., /api/contents/{path}, /api/kernels, etc.).

4. Drill into Tornado Handler Mappings

Rather than Flask Blueprints, Jupyter Server uses Tornado handlers. To see which regex maps to which Python class: 

python3 - <<'PYCODE'
from jupyter_server import serverapp
app = serverapp.ServerApp()
app.initialize([])

# Default host_patterns and routes
host_patterns, default_handlers = (
    app.web_app.add_handlers.__wrapped__.__defaults__
)
for host_pat, routes in host_patterns:
    print(f"\nHost pattern: {host_pat}")
    for regex, handler in routes:
        print(f"  {regex.pattern:40} → {handler.__name__}")
PYCODE

This outputs lines like: 

Host pattern: .*$
  /api/contents/(.*)           → ContentsHandler
  /api/kernels                  → KernelHandler
  ...

5. Search Source for Key Concepts

If you want to audit a concept (e.g., authentication, file I/O), grep inside the module directories: 

grep -R --include="*.py" -n "Auth" "$(python3 - <<<'PYCODE'
import jupyter_server, os
print(os.path.dirname(jupyter_server.__file__))
PYCODE)"

Modify the search term for other patterns (e.g., ContentsHandler, FileManagerMixin, etc.).

6. Quick Python REPL Exploration

For ad-hoc introspection, start a REPL and import components: 

python3
>>> from jupyter_server.serverapp import ServerApp
>>> app = ServerApp()
>>> app.initialize([])
>>> app.web_app.settings.keys()
>>> app.web_app.settings['kernel_manager_class']


tux@camelot:~$ python3
>>> from jupyter_server.serverapp import ServerApp
>>> app = ServerApp()
>>> app.initialize([])
>>> app.web_app.settings.keys()
>>> app.web_app.settings['kernel_manager_class']
Python 3.13.5 (main, Jun 12 2025, 00:00:00) [GCC 15.1.1 20250521 (Red Hat 15.1.1-2)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

This approach helps you poke at internal settings and configurations.

Now you have a turnkey guide for any explorer to map Camelot’s Python environment and Jupyter Server’s REST API — perfect for your Encyclopedia!

7. Running, Restarting, and Testing Jupyter Server

7.1 Check if Jupyter is running 

# List Jupyter processes
ps aux | grep -E 'jupyter-(lab|notebook|server)' | grep -v grep

# Or check the systemd service (if enabled)
systemctl status jupyter

  

root@camelot:/home/tux/sh1re# ps aux | grep -E 'jupyter-(lab|notebook|server)' | grep -v grep
tux        56396  0.0  0.7 337684 99768 pts/4    Sl   18:46   0:01 /usr/bin/python3 -P /usr/bin/jupyter-lab --config=/home/jupyter/.jupyter/jupyter_server_config.py
tux        56857  0.1  0.6 185080 92752 pts/4    S+   19:45   0:00 /usr/bin/python3 -sP /usr/bin/jupyter-server --ip=0.0.0.0 --no-browser
[1]+  Exit 1                  nohup jupyter lab --config=/home/jupyter/.jupyter/jupyter_server_config.py

  

allison@frodo:~$ curl -kvvv http://camelot:8888/lab
* Host camelot:8888 was resolved.
* IPv6: (none)
* IPv4: 10.20.30.1
*   Trying 10.20.30.1:8888...
* connect to 10.20.30.1 port 8888 from 10.20.30.2 port 55576 failed: Connection refused
* Failed to connect to camelot port 8888 after 2 ms: Couldn't connect to server
* Closing connection
curl: (7) Failed to connect to camelot port 8888 after 2 ms: Couldn't connect to server
allison@frodo:~$

 

7.2 Start or Restart Jupyter

  • If running manually (from shell): 

    # Kill any leftover process if stuck
pkill -f 'jupyter-server'

# Start in the background
nohup jupyter lab \
  --config=/home/jupyter/.jupyter/jupyter_server_config.py \
  &

  • If using systemd: 

    sudo systemctl restart jupyter
sudo systemctl status jupyter

7.3 Verify Connectivity

  1. Local curl test (on Camelot): 

    curl -i http://localhost:8888/lab

tux@camelot:~$ curl -i http://localhost:8888/lab
HTTP/1.1 302 Found
Server: TornadoServer/6.4.1
Content-Type: text/html; charset=UTF-8
Date: Sun, 27 Jul 2025 23:39:37 GMT
X-Content-Type-Options: nosniff
Content-Security-Policy: frame-ancestors 'self'; report-uri /api/security/csp-report
Location: /login?next=%2Flab
Content-Length: 0
    • See: HTTP/1.1 302 Found

  2. Remote test (from another host): 

    curl -i http://camelot:8888/lab
    • Should see the same headers/content; if not, check firewall or binding.
  3. Browser check:
    • Open http://<camelot-host>:8888/lab in your web browser.

    • If prompted for password and you see the Lab interface, you’re good.

       

Server App 


Server App

python3 - <<'PYCODE'
from jupyter_server import serverapp
app = serverapp.ServerApp()
app.initialize([])

# Default host_patterns and routes
host_patterns, default_handlers = (
    app.web_app.add_handlers.__wrapped__.__defaults__
)
for host_pat, routes in host_patterns:
    print(f"\nHost pattern: {host_pat}")
    for regex, handler in routes:
        print(f"  {regex.pattern:40} → {handler.__name__}")
PYCODE

[I 2025-07-27 19:11:04.538 ServerApp] jupyter_lsp | extension was successfully linked.
[I 2025-07-27 19:11:04.540 ServerApp] jupyter_server_terminals | extension was successfully linked.
[I 2025-07-27 19:11:04.543 ServerApp] jupyterlab | extension was successfully linked.
[I 2025-07-27 19:11:04.545 ServerApp] notebook | extension was successfully linked.
[I 2025-07-27 19:11:04.687 ServerApp] notebook_shim | extension was successfully linked.
[I 2025-07-27 19:11:04.700 ServerApp] notebook_shim | extension was successfully loaded.
[I 2025-07-27 19:11:04.702 ServerApp] jupyter_lsp | extension was successfully loaded.
[I 2025-07-27 19:11:04.702 ServerApp] jupyter_server_terminals | extension was successfully loaded.
[I 2025-07-27 19:11:04.704 LabApp] JupyterLab extension loaded from /usr/lib/python3.13/site-packages/jupyterlab
[I 2025-07-27 19:11:04.704 LabApp] JupyterLab application directory is /usr/share/jupyter/lab
[I 2025-07-27 19:11:04.704 LabApp] Extension Manager is 'pypi'.
[I 2025-07-27 19:11:04.712 ServerApp] jupyterlab | extension was successfully loaded.
[I 2025-07-27 19:11:04.714 ServerApp] notebook | extension was successfully loaded.
[I 2025-07-27 19:11:04.715 ServerApp] The port 8888 is already in use, trying another port.
Traceback (most recent call last):
  File "<stdin>", line 7, in <module>
AttributeError: 'function' object has no attribute '__wrapped__'
tux@camelot:~$

 

 

 

 

7.4 Troubleshooting Tips

  • No response / Connection refused: Ensure Jupyter is bound to 0.0.0.0 or localhost as expected. Check c.ServerApp.ip in your config.
  • Authentication errors: Re-run jupyter server password to reset your password hash.
  • Firewall issues: Re-verify with firewall-cmd --list-ports that 8888/tcp is open.

  • Logs: When run via systemd, view logs with: 

    journalctl -u jupyter -f

 

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