nteract/papermill

kernel_name argument of papermill.execute seems to have no effect.

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#856 opened on Dec 17, 2025

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Description

🐛 Bug

The kernel_name argument of papermill.execute seems to have no effect. The executing notebook uses the Jupyter kernel specified in the original notebook's metatdata. Using papermill v2.6.0. Or at least the display_name in the metadata is unchanged, this is what jupyter hub uses to display the name of the kernal being used.

Something along the lines of this function should fix this:

import nbformat as nbf

def change_notebook_kernel(input_path, output_path, kernel):
    """
    Change a Jupyter Notebook's kernel.

    Parameters
    ----------
    input_path: str
        Path to the input notebook.
    output_path: str
        Path to the output notebook.
    kernel: str
        Name of the kernel_name to change to.
    """
    notebook = nbf.read(input_path, as_version=4)
    notebook['metadata']['kernelspec']['name'] = kernel
    notebook['metadata']['kernelspec']['display_name'] = kernel
    nbf.write(notebook, output_path)

Contributor guide

Research direction
Trace the execution path of papermill.execute to identify where the kernel name parameter is applied or ignored. Check how the notebook metadata kernelspec is set and ensure it is overridden with the provided kernel name.
Tech stack
python
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Fresh
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Clear
Prerequisites
PythonGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75