Don't start JupyterLab if configuration is invalid - jupyter

Question

When JupyterLab tries to start, in some occasions, the config file may be invalid, and Jupyterlab starts regardless in default port 8888.
Currently I have a JupyterLab service defined as follows, but I also try to start it manually and got the same results.
An example when config file may be invalid is when a library is not available to be imported.
I want to prevent Jupyter to start and fail gracefully.
[Unit]
Description=Jupyter Service
[Service]
Type=simple
PIDFile=/run/jupyter.pid
ExecStart=/bin/bash --login -c '/opt/conda/bin/jupyter lab --config=/home/jupyter/.jupyter/jupyter_notebook_config.py'
User=jupyter
Group=jupyter
WorkingDirectory=/home/jupyter
Restart=no
[Install]
WantedBy=multi-user.target
(base) root#ab-test1:/home/jupyter/.jupyter# service jupyter status
● jupyter.service - Jupyter Notebook Service
Loaded: loaded (/lib/systemd/system/jupyter.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2022-02-02 07:53:24 UTC; 3s ago
Main PID: 335 (jupyter-lab)
Tasks: 1 (limit: 4915)
Memory: 64.0M (high: 14.3G max: 14.3G)
CGroup: /system.slice/jupyter.service
└─335 /opt/conda/bin/python3.7 /opt/conda/bin/jupyter-lab --config=/home/jupyter/.jupyter/jupyter_notebook_config.py
Feb 02 07:53:27 ab-test1 bash[335]: Traceback (most recent call last):
Feb 02 07:53:27 ab-test1 bash[335]: File "/opt/conda/lib/python3.7/site-packages/traitlets/config/application.py", line 738, in _load_config_files
Feb 02 07:53:27 ab-test1 bash[335]: config = loader.load_config()
Feb 02 07:53:27 ab-test1 bash[335]: File "/opt/conda/lib/python3.7/site-packages/traitlets/config/loader.py", line 614, in load_config
Feb 02 07:53:27 ab-test1 bash[335]: self._read_file_as_dict()
Feb 02 07:53:27 ab-test1 bash[335]: File "/opt/conda/lib/python3.7/site-packages/traitlets/config/loader.py", line 646, in _read_file_as_dict
Feb 02 07:53:27 ab-test1 bash[335]: exec(compile(f.read(), conf_filename, 'exec'), namespace, namespace)
Feb 02 07:53:27 ab-test1 bash[335]: File "/home/jupyter/.jupyter/jupyter_notebook_config.py", line 3, in <module>
Feb 02 07:53:27 ab-test1 bash[335]: import tensorflow
Feb 02 07:53:27 ab-test1 bash[335]: ModuleNotFoundError: No module named 'tensorflow'
(base) root#ab-test1:/home/jupyter/.jupyter# service jupyter status
● jupyter.service - Jupyter Notebook Service
Loaded: loaded (/lib/systemd/system/jupyter.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2022-02-02 07:53:24 UTC; 6s ago
Main PID: 335 (jupyter-lab)
Tasks: 2 (limit: 4915)
Memory: 138.6M (high: 14.3G max: 14.3G)
CGroup: /system.slice/jupyter.service
└─335 /opt/conda/bin/python3.7 /opt/conda/bin/jupyter-lab --config=/home/jupyter/.jupyter/jupyter_notebook_config.py
Feb 02 07:53:29 ab-test1 bash[335]: [I 2022-02-02 07:53:29.644 ServerApp] or http://127.0.0.1:8888/lab?token=ead21ce39f979fe916e7e041134da576feb28b839bd99577
Feb 02 07:53:29 ab-test1 bash[335]: [I 2022-02-02 07:53:29.644 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation)
Feb 02 07:53:29 ab-test1 bash[335]: [W 2022-02-02 07:53:29.648 ServerApp] No web browser found: could not locate runnable browser.
Feb 02 07:53:29 ab-test1 bash[335]: [C 2022-02-02 07:53:29.648 ServerApp]
Feb 02 07:53:29 ab-test1 bash[335]:
Feb 02 07:53:29 ab-test1 bash[335]: To access the server, open this file in a browser:
Feb 02 07:53:29 ab-test1 bash[335]: file:///home/jupyter/.local/share/jupyter/runtime/jpserver-335-open.html
Feb 02 07:53:29 ab-test1 bash[335]: Or copy and paste one of these URLs:
Feb 02 07:53:29 ab-test1 bash[335]: http://localhost:8888/lab?token=ead21ce39f979fe916e7e041134da576feb28b839bd99577
Feb 02 07:53:29 ab-test1 bash[335]: or http://127.0.0.1:8888/lab?token=ead21ce39f979fe916e7e041134da576feb28b839bd99577
Logs:
/opt/conda/bin/jupyter-lab --debug --config=/home/jupyter/.jupyter/jupyter_notebook_config.py
[D 2022-02-02 08:09:28.170 ServerApp] Searching ['/home/gogasca', '/home/gogasca/.jupyter', '/home/gogasca/.local/etc/jupyter', '/opt/conda/etc/jupyter', '/usr/local/etc/jupyter', '/etc/jupyter'] for config files
[D 2022-02-02 08:09:28.170 ServerApp] Looking for jupyter_config in /etc/jupyter
[D 2022-02-02 08:09:28.170 ServerApp] Looking for jupyter_config in /usr/local/etc/jupyter
[D 2022-02-02 08:09:28.170 ServerApp] Looking for jupyter_config in /opt/conda/etc/jupyter
[D 2022-02-02 08:09:28.171 ServerApp] Loaded config file: /opt/conda/etc/jupyter/jupyter_config.json
[D 2022-02-02 08:09:28.171 ServerApp] Looking for jupyter_config in /home/gogasca/.local/etc/jupyter
[D 2022-02-02 08:09:28.171 ServerApp] Looking for jupyter_config in /home/gogasca/.jupyter
[D 2022-02-02 08:09:28.171 ServerApp] Looking for jupyter_config in /home/gogasca
[D 2022-02-02 08:09:28.173 ServerApp] Looking for jupyter_notebook_config in /home/jupyter/.jupyter
[E 2022-02-02 08:09:28.174 ServerApp] Exception while loading config file /home/jupyter/.jupyter/jupyter_notebook_config.py
Traceback (most recent call last):
File "/opt/conda/lib/python3.7/site-packages/traitlets/config/application.py", line 738, in _load_config_files
config = loader.load_config()
File "/opt/conda/lib/python3.7/site-packages/traitlets/config/loader.py", line 614, in load_config
self._read_file_as_dict()
File "/opt/conda/lib/python3.7/site-packages/traitlets/config/loader.py", line 646, in _read_file_as_dict
exec(compile(f.read(), conf_filename, 'exec'), namespace, namespace)
File "/home/jupyter/.jupyter/jupyter_notebook_config.py", line 3, in <module>
import tensorflow
ModuleNotFoundError: No module named 'tensorflow'
[D 2022-02-02 08:09:28.177 ServerApp] Paths used for configuration of jupyter_server_config:
/etc/jupyter/jupyter_server_config.json
[D 2022-02-02 08:09:28.178 ServerApp] Paths used for configuration of jupyter_server_config:
/usr/local/etc/jupyter/jupyter_server_config.json
[D 2022-02-02 08:09:28.178 ServerApp] Paths used for configuration of jupyter_server_config:
/opt/conda/etc/jupyter/jupyter_server_config.d/beatrix_jupyterlab.json
/opt/conda/etc/jupyter/jupyter_server_config.d/jupyter-server-proxy-jupyterserverextension.json
/opt/conda/etc/jupyter/jupyter_server_config.d/jupyter_server_mathjax.json
/opt/conda/etc/jupyter/jupyter_server_config.d/jupyterlab.json
/opt/conda/etc/jupyter/jupyter_server_config.d/jupyterlab_git.json
/opt/conda/etc/jupyter/jupyter_server_config.d/jupytext.json
/opt/conda/etc/jupyter/jupyter_server_config.d/nbclassic.json
/opt/conda/etc/jupyter/jupyter_server_config.d/nbdime.json
/opt/conda/etc/jupyter/jupyter_server_config.json
[D 2022-02-02 08:09:28.179 ServerApp] Paths used for configuration of jupyter_server_config:
/home/gogasca/.local/etc/jupyter/jupyter_server_config.json
[D 2022-02-02 08:09:28.180 ServerApp] Paths used for configuration of jupyter_server_config:
/home/gogasca/.jupyter/jupyter_server_config.json
generated new fontManager
/opt/conda/lib/python3.7/site-packages/jupyter_server_mathjax/app.py:40: FutureWarning: The alias `_()` will be deprecated. Use `_i18n()` instead.
help=_("""The MathJax.js configuration file that is to be used."""),
[I 2022-02-02 08:09:32.735 ServerApp] beatrix_jupyterlab | extension was successfully linked.
[W 2022-02-02 08:09:32.737 MathJaxExtension] Config option `kernel_spec_manager_class` not recognized by `MathJaxExtension`.
[W 2022-02-02 08:09:32.738 MathJaxExtension] Config option `kernel_spec_manager_class` not recognized by `MathJaxExtension`.
[W 2022-02-02 08:09:32.743 MathJaxExtension] Config option `kernel_spec_manager_class` not recognized by `MathJaxExtension`.
[D 2022-02-02 08:09:32.744 MathJaxExtension] Config changed: {'JupyterApp': {'kernel_spec_manager_class': 'nb_conda_kernels.CondaKernelSpecManager'}, 'ServerApp': {'config_file': '/home/jupyter/.jupyter/jupyter_notebook_config.py', 'log_level': 'DEBUG', 'jpserver_extensions': <LazyConfigValue {'update': {'beatrix_jupyterlab': True, 'jupyter_server_mathjax': True, 'jupyter_server_proxy': True, 'jupyterlab_git': True, 'jupytext': True, 'nbclassic': True, 'nbdime': True}}>}, 'ExtensionApp': {'log_level': 'DEBUG'}}
[D 2022-02-02 08:09:32.745 ServerApp] Config changed: {'ServerApp': {'config_file': '/home/jupyter/.jupyter/jupyter_notebook_config.py', 'log_level': 'DEBUG', 'jpserver_extensions': <LazyConfigValue value={'jupyterlab': True, 'beatrix_jupyterlab': True, 'jupyter_server_mathjax': True, 'jupyter_server_proxy': True, 'jupyterlab_git': True, 'jupytext': True, 'nbclassic': True, 'nbdime': True}>}, 'ExtensionApp': {'log_level': 'DEBUG'}, 'JupyterApp': {'kernel_spec_manager_class': 'nb_conda_kernels.CondaKernelSpecManager'}}
[I 2022-02-02 08:09:32.746 ServerApp] jupyter_server_mathjax | extension was successfully linked.
[I 2022-02-02 08:09:32.746 ServerApp] jupyter_server_proxy | extension was successfully linked.
[W 2022-02-02 08:09:32.749 LabApp] Config option `kernel_spec_manager_class` not recognized by `LabApp`.
[W 2022-02-02 08:09:32.753 LabApp] Config option `kernel_spec_manager_class` not recognized by `LabApp`.
[W 2022-02-02 08:09:32.760 LabApp] Config option `kernel_spec_manager_class` not recognized by `LabApp`.
[D 2022-02-02 08:09:32.761 LabApp] Config changed: {'JupyterApp': {'kernel_spec_manager_class': 'nb_conda_kernels.CondaKernelSpecManager'}, 'NotebookApp': {}, 'ServerApp': {'config_file': '/home/jupyter/.jupyter/jupyter_notebook_config.py', 'log_level': 'DEBUG', 'jpserver_extensions': <LazyConfigValue value={'jupyterlab': True, 'beatrix_jupyterlab': True, 'jupyter_server_mathjax': True, 'jupyter_server_proxy': True, 'jupyterlab_git': True, 'jupytext': True, 'nbclassic': True, 'nbdime': True}>}, 'ExtensionApp': {'log_level': 'DEBUG'}}
[I 2022-02-02 08:09:32.762 ServerApp] jupyterlab | extension was successfully linked.
[I 2022-02-02 08:09:32.762 ServerApp] jupyterlab_git | extension was successfully linked.
[I 2022-02-02 08:09:32.762 ServerApp] jupytext | extension was successfully linked.
[W 2022-02-02 08:09:32.765 NotebookApp] Config option `kernel_spec_manager_class` not recognized by `NotebookApp`.
[W 2022-02-02 08:09:32.768 NotebookApp] Config option `kernel_spec_manager_class` not recognized by `NotebookApp`.
[W 2022-02-02 08:09:32.774 NotebookApp] Config option `kernel_spec_manager_class` not recognized by `NotebookApp`.
[D 2022-02-02 08:09:32.774 NotebookApp] Config changed: {'JupyterApp': {'kernel_spec_manager_class': 'nb_conda_kernels.CondaKernelSpecManager'}, 'NotebookApp': {'nbserver_extensions': {'nb_conda': True, 'jupyter_http_over_ws': True}}, 'ServerApp': {'config_file': '/home/jupyter/.jupyter/jupyter_notebook_config.py', 'log_level': 'DEBUG', 'jpserver_extensions': <LazyConfigValue value={'jupyterlab': True, 'beatrix_jupyterlab': True, 'jupyter_server_mathjax': True, 'jupyter_server_proxy': True, 'jupyterlab_git': True, 'jupytext': True, 'nbclassic': True, 'nbdime': True}>}, 'ExtensionApp': {'log_level': 'DEBUG'}}
[I 2022-02-02 08:09:32.778 ServerApp] Writing Jupyter server cookie secret to /home/gogasca/.local/share/jupyter/runtime/jupyter_cookie_secret
[D 2022-02-02 08:09:32.782 ServerApp] Paths used for configuration of jupyter_notebook_config:
/home/gogasca/.jupyter/jupyter_notebook_config.json
[D 2022-02-02 08:09:32.782 ServerApp] Paths used for configuration of jupyter_notebook_config:
/etc/jupyter/jupyter_notebook_config.json
[D 2022-02-02 08:09:32.783 ServerApp] Paths used for configuration of jupyter_notebook_config:
/usr/local/etc/jupyter/jupyter_notebook_config.json
[D 2022-02-02 08:09:32.784 ServerApp] Paths used for configuration of jupyter_notebook_config:
/opt/conda/etc/jupyter/jupyter_notebook_config.d/jupyter-server-proxy-notebookserverextension.json
/opt/conda/etc/jupyter/jupyter_notebook_config.d/jupyterlab.json
/opt/conda/etc/jupyter/jupyter_notebook_config.d/jupyterlab_git.json
/opt/conda/etc/jupyter/jupyter_notebook_config.d/jupytext.json
/opt/conda/etc/jupyter/jupyter_notebook_config.d/nbdime.json
/opt/conda/etc/jupyter/jupyter_notebook_config.json
[D 2022-02-02 08:09:32.784 ServerApp] Paths used for configuration of jupyter_notebook_config:
/home/gogasca/.local/etc/jupyter/jupyter_notebook_config.json
[D 2022-02-02 08:09:32.785 ServerApp] Paths used for configuration of jupyter_notebook_config:
/home/gogasca/.jupyter/jupyter_notebook_config.json
[I 2022-02-02 08:09:32.787 ServerApp] nb_conda | extension was found and enabled by nbclassic. Consider moving the extension to Jupyter Server's extension paths.
[I 2022-02-02 08:09:32.787 ServerApp] nb_conda | extension was successfully linked.
[I 2022-02-02 08:09:32.789 ServerApp] jupyter_http_over_ws | extension was found and enabled by nbclassic. Consider moving the extension to Jupyter Server's extension paths.
[I 2022-02-02 08:09:32.789 ServerApp] jupyter_http_over_ws | extension was successfully linked.
[I 2022-02-02 08:09:32.789 ServerApp] nbclassic | extension was successfully linked.
[I 2022-02-02 08:09:32.789 ServerApp] nbdime | extension was successfully linked.
[D 2022-02-02 08:09:32.790 ServerApp] Config changed: {'ExtensionApp': {'log_level': 'DEBUG'}, 'JupyterApp': {'kernel_spec_manager_class': 'nb_conda_kernels.CondaKernelSpecManager'}, 'NotebookApp': {'nbserver_extensions': {'nb_conda': True, 'jupyter_http_over_ws': True}}, 'ServerApp': {'config_file': '/home/jupyter/.jupyter/jupyter_notebook_config.py', 'log_level': 'DEBUG', 'jpserver_extensions': <LazyConfigValue value={'jupyterlab': True, 'beatrix_jupyterlab': True, 'jupyter_server_mathjax': True, 'jupyter_server_proxy': True, 'jupyterlab_git': True, 'jupytext': True, 'nbclassic': True, 'nbdime': True}>}}
[D 2022-02-02 08:09:32.791 ServerApp] Raising open file limit: soft 1024->4096; hard 1048576->1048576
[D 2022-02-02 08:09:32.792 ServerApp] [nb_conda_kernels] refreshing conda info
[I 2022-02-02 08:09:33.136 ServerApp] [nb_conda_kernels] enabled, 1 kernels found
[I 2022-02-02 08:09:33.161 ServerApp] nbclassic | extension was successfully loaded.
[I 2022-02-02 08:09:33.163 ServerApp] beatrix_jupyterlab | extension was successfully loaded.
jupyter_http_over_ws extension initialized. Listening on /http_over_websocket
[I 2022-02-02 08:09:33.164 ServerApp] jupyter_http_over_ws | extension was successfully loaded.
[I 2022-02-02 08:09:33.165 ServerApp] jupyter_server_mathjax | extension was successfully loaded.
[I 2022-02-02 08:09:33.177 ServerApp] jupyter_server_proxy | extension was successfully loaded.
[I 2022-02-02 08:09:33.178 LabApp] JupyterLab extension loaded from /opt/conda/lib/python3.7/site-packages/jupyterlab
[I 2022-02-02 08:09:33.178 LabApp] JupyterLab application directory is /opt/conda/share/jupyter/lab
[I 2022-02-02 08:09:33.183 ServerApp] jupyterlab | extension was successfully loaded.
[I 2022-02-02 08:09:33.188 ServerApp] jupyterlab_git | extension was successfully loaded.
[I 2022-02-02 08:09:33.188 ServerApp] [Jupytext Server Extension] Deriving a JupytextContentsManager from LargeFileManager
[I 2022-02-02 08:09:33.190 ServerApp] jupytext | extension was successfully loaded.
[I 2022-02-02 08:09:33.191 ServerApp] [nb_conda] enabled
[I 2022-02-02 08:09:33.191 ServerApp] nb_conda | extension was successfully loaded.
[D 2022-02-02 08:09:33.253 ServerApp] Using default logger
[D 2022-02-02 08:09:33.254 ServerApp] Using default logger
[D 2022-02-02 08:09:33.254 ServerApp] Using default logger
[D 2022-02-02 08:09:33.254 ServerApp] Using default logger
[D 2022-02-02 08:09:33.254 ServerApp] Using default logger
[D 2022-02-02 08:09:33.254 ServerApp] Using default logger
[I 2022-02-02 08:09:33.257 ServerApp] nbdime | extension was successfully loaded.
[I 2022-02-02 08:09:33.258 ServerApp] Serving notebooks from local directory: /home/gogasca
[I 2022-02-02 08:09:33.258 ServerApp] Jupyter Server 1.13.1 is running at:
[I 2022-02-02 08:09:33.258 ServerApp] http://localhost:8888/lab?token=0be64d1115747cdd0726876d15ece5ba15c4032127b508f1
[I 2022-02-02 08:09:33.258 ServerApp] or http://127.0.0.1:8888/lab?token=0be64d1115747cdd0726876d15ece5ba15c4032127b508f1
[I 2022-02-02 08:09:33.258 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[W 2022-02-02 08:09:33.263 ServerApp] No web browser found: could not locate runnable browser.
[C 2022-02-02 08:09:33.263 ServerApp]
To access the server, open this file in a browser:
file:///home/gogasca/.local/share/jupyter/runtime/jpserver-4572-open.html
Or copy and paste one of these URLs:
http://localhost:8888/lab?token=0be64d1115747cdd0726876d15ece5ba15c4032127b508f1
or http://127.0.0.1:8888/lab?token=0be64d1115747cdd0726876d15ece5ba15c4032127b508f1

Answer 1

You can enforce failure on configuration errors by configuring environment variable TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR to 1 or true (see docs); on Linux this can be done by prepending the startup command like so:
TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR=1 jupyter lab
If you would like it to become a new default, there is a feature request marked as good first issue here: https://github.com/jupyterlab/jupyterlab/issues/5716