Unable to get notebook filename on JupyterLab 3.0

[kangwoo]

/kind bug

What steps did you take and what happened:

• The following code was executed in JupyterLab 3.0.

  import uuid
  from kubeflow import fairing
  
  CONTAINER_REGISTRY = 'kangwoo'
  
  namespace = 'admin'
  job_name = f'fairing-notebook-append-job-{uuid.uuid4().hex[:4]}'
  
  fairing.config.set_builder('append', registry=CONTAINER_REGISTRY, image_name="fairing-notebook-append-job",
                             base_image="tensorflow/tensorflow:2.1.0-py3")
  
  fairing.config.set_deployer('job', namespace=namespace, job_name=job_name, cleanup=False, stream_log=True)
  
  fairing.config.run()

• Error

  
  ~/.local/lib/python3.6/site-packages/kubeflow/fairing/preprocessors/converted_notebook.py in preprocess(self)
  119         exporter = nbconvert.PythonExporter()
  120         exporter.register_preprocessor(self.notebook_preprocessor, enabled=True)
  --> 121         contents, _ = exporter.from_filename(self.notebook_file)
  122         converted_notebook = Path(self.notebook_file).with_suffix('.py')
  123         if converted_notebook.exists() and not self.overwrite:

/usr/local/lib/python3.6/dist-packages/nbconvert/exporters/exporter.py in from_filename(self, filename, resources, **kw) 165 if not 'metadata' in resources or resources['metadata'] == '': 166 resources['metadata'] = ResourcesDict() --> 167 path, basename = os.path.split(filename) 168 notebook_name = os.path.splitext(basename)[0] 169 resources['metadata']['name'] = notebook_name

/usr/lib/python3.6/posixpath.py in split(p) 105 """Split a pathname. Returns tuple "(head, tail)" where "tail" is 106 everything after the final slash. Either part may be empty.""" --> 107 p = os.fspath(p) 108 sep = _get_sep(p) 109 i = p.rfind(sep) + 1

TypeError: expected str, bytes or os.PathLike object, not NoneType

**What did you expect to happen:**

**Anything else you would like to add:**
Utility function does not return file name.
In[]

from kubeflow.fairing.notebook import notebook_util print(notebook_util.get_notebook_name())

Out[]

None

**Environment:**

- Fairing version: 1.0.2
- Kubeflow version: 1.2.0
- Minikube version:
- Kubernetes version: 1.20.1
- OS (e.g. from `/etc/os-release`): Ubuntu 20.04.2 LTS

**NOTE**: