On notebook download, custom ContentsManager raises StaticFileHandler.initialize() exception

[miraculixx]

Description

When implementing a custom ContentsManager, jupyter_server raises the following exception upon downloading files from Jupyter Lab, and the file will not be downloaded.

TypeError: StaticFileHandler.initialize() missing 1 required positional argument: 'path'

Reproduce

Implement a custom ContentsManager according to the guideline as documented here.

1. Run Jupyter Lab with the c.ServerApp.contents_manager_class=module.CustomContentsManager
2. Create and select a notebook, Go to File > Download
3. The file will not be downloaded, and the console will show the above exception

Expected behavior

The file is downloaded and no exception is raised.

Context

• Operating System and version: Linux Mint 21.1 Vera
• Browser and version: Google Chrome 115.0.5790.170
• Jupyter Server version: 2.7.0

This used to work (i.e. did not raise an exception) in versions jupyter_server<2, however I did not investigate the exact version that changed the behavior.

Troubleshoot Output

$ jupyter troubleshoot | grep -iE "jupyter-server|jupyterlab|nbclassic|notebook"
        jupyterlab                 4.0.4
        jupyterlab-pygments        0.2.2
        jupyterlab_server          2.24.0
        nbclassic                  1.0.0
        notebook                   7.0.2
        notebook_shim              0.2.3
        jupyter-server            2.7.0                    pypi_0    pypi
        jupyter-server-terminals  0.4.4                    pypi_0    pypi
        jupyterlab                4.0.4                    pypi_0    pypi
        jupyterlab-pygments       0.2.2                    pypi_0    pypi
        jupyterlab-server         2.24.0                   pypi_0    pypi
        nbclassic                 1.0.0                    pypi_0    pypi
        notebook                  7.0.2                    pypi_0    pypi
        notebook-shim             0.2.3                    pypi_0    pypi
              - jupyter-server==2.7.0
              - jupyter-server-terminals==0.4.4
              - jupyterlab==4.0.4
              - jupyterlab-pygments==0.2.2
              - jupyterlab-server==2.24.0
              - nbclassic==1.0.0
              - notebook==7.0.2
              - notebook-shim==0.2.3

Command Line Output

[I 2023-08-12 13:39:09.343 ServerApp] nbclassic | extension was successfully loaded.                                                                                                          
[I 2023-08-12 13:39:09.346 ServerApp] notebook | extension was successfully loaded.                                                                                                           
[I 2023-08-12 13:39:09.347 ServerApp] Serving contents                                                                                                                                        
[I 2023-08-12 13:39:09.347 ServerApp] Jupyter Server 2.7.0 is running at:                                                                                                                     
[I 2023-08-12 13:39:09.347 ServerApp] http://localhost:8888/lab?token=77428c315021ebc6de85ce58f0d17c82f263b4f50ed5b57c                                                                        
[I 2023-08-12 13:39:09.347 ServerApp]     http://127.0.0.1:8888/lab?token=77428c315021ebc6de85ce58f0d17c82f263b4f50ed5b57c                                                                    
[I 2023-08-12 13:39:09.347 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
(...)
[E 2023-08-12 13:39:20.279 ServerApp] Uncaught exception                                                                                                                                      
    Traceback (most recent call last):                                                                                                                                                        
      File "/home/user/miniforge3/envs/omegaml-ce/lib/python3.10/site-packages/tornado/http1connection.py", line 276, in _read_message                                                     
        delegate.finish()                                                                                                                                                                     
      File "/home/user/miniforge3/envs/omegaml-ce/lib/python3.10/site-packages/tornado/routing.py", line 268, in finish                                                                    
        self.delegate.finish()                                                                                                                                                                
      File "/home/user/miniforge3/envs/omegaml-ce/lib/python3.10/site-packages/tornado/web.py", line 2398, in finish                                                                       
        self.execute()                                                                                                                                                                        
      File "/home/user/miniforge3/envs/omegaml-ce/lib/python3.10/site-packages/tornado/web.py", line 2420, in execute                                                                      
        self.handler = self.handler_class(                                                                                                                                                    
      File "/home/user/miniforge3/envs/omegaml-ce/lib/python3.10/site-packages/tornado/web.py", line 239, in __init__                                                                      
        self.initialize(**kwargs)  # type: ignore                                                                                                                                             
    TypeError: StaticFileHandler.initialize() missing 1 required positional argument: 'path'

Browser Output

(no relevant console output)

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[miraculixx]

The following work around seems the fix the immediate issue, however I am not sure of the implications of this.

In your custom ContentsManager, add the following.

class CustomContentsManager(ContentsManager):
     .... 
    @default('files_handler_params')
    def _files_handler_params_default(self):
        return {'path': self.root_dir}

Alternatively, add the following in your jupyter_server_config.py

c.ContentsManager.file_handler_params = { 'path': '/valid/path' }

What this does

• ensure that ContentsManager.files_handler_class=FilesHandler gets has a path attribute on initialize()
• this only happens when dealing with local files, e.g. when downloading a notebook
• source of the issue is that ContentsManager.files_handler_params is not set

[fakhavan]

I've faced the same error while using a hybridcontents content manager to allow both LargeFileManager and S3Contents in our jupyter hub deployment with helm.
I tried applying the suggestion from @miraculixx by passing on files_handler_params into the LargeFileManager manager class like this:

## Contents of `jupyter_notebook_config.py` file


HOME_DIR = path.join("/home", environ["NB_USER"])
# Configure the variables for s3contents library for shared space


# Configure HybridContentsManager to use LargeFileManager for root dir and personal-space and S3ContentsManager for s3-shared-space
c.HybridContentsManager.manager_classes = {
    # making the root dir read-only to contain guides and other read-only content
    "": LargeFileManager,
    # making the personal space read-write into an EBS volume
    "personal-space": LargeFileManager,
    # making the shared space read-write into an S3 bucket
    "shared-space": S3ContentsManager,
}

c.HybridContentsManager.manager_kwargs = {
    # using /tmp/read-only as the root dir, which is read-only, and contains guides that users would see when they open JupyterHub
    "": {"root_dir": READ_ONLY_ROOT_DIR},
    # using the user's home dir as the personal space, and is mounted to an EBS volume which is presisted across sessions
    "personal-space": {"root_dir": HOME_DIR, "files_handler_params": {"path": HOME_DIR}},
    # using the S3 bucket as the shared space, and is mounted to an S3 bucket which is presisted across sessions
    "shared-space": {
        "endpoint_url": S3_ENDPOINT_URL,
        "bucket": S3_BUCKET_NAME,
        "region_name": S3_REGION_NAME,
    },
}

# To prevent `directory not found ""` error when opening JupyterLab
c.ServerApp.root_dir = HOME_DIR

The above code is amended into jupyter_notebook_config.py file on jupyterhub server startup, however, this does not solve my issue. I assume the files_handler_params is not passed in the right format or is not being added into to the right file i.e. jupyter_notebook_config.py instead of jupyter_server_config.py, however I'm not sure what's the correct way to handle the issue with my setup.
I am wondering if anyone has run into similar issues when using other content managers like HybridContents or has any idea on how to solve this.

Cheers

[vlobachevsky]

@fakhavan I was able to resolve this by setting files_handler_params in HybridContentsManager:

c.HybridContentsManager.files_handler_params = { 'path': HOME_DIR }