Executing and cacheing your content

MyST-NB can automatically run and cache notebooks contained in your project using jupyter-cache. Notebooks can either be run each time the documentation is built, or cached locally so that re-runs occur only when code cells have changed.

Cacheing behavior is controlled with configuration in your conf.py file. See the sections below for each configuration option and its effect.

Triggering notebook execution

To trigger the execution of notebook pages, use the following configuration in conf.py

jupyter_execute_notebooks = "auto"

By default, this will only execute notebooks that are missing at least one output. If a notebook has all of its outputs populated, then it will not be executed.

To force the execution of all notebooks, regardless of their outputs, change the above configuration value to:

jupyter_execute_notebooks = "force"

To cache execution outputs with jupyter-cache, change the above configuration value to:

jupyter_execute_notebooks = "cache"

See Cacheing the notebook execution for more information.

To turn off notebook execution, change the above configuration value to:

jupyter_execute_notebooks = "off"

To exclude certain file patterns from execution, use the following configuration:

execution_excludepatterns = ['list', 'of', '*patterns']

Any file that matches one of the items in execution_excludepatterns will not be executed.

Cacheing the notebook execution

As mentioned above, you can cache the results of executing a notebook page by setting

jupyter_execute_notebooks = "cache"

in your conf.py file. In this case, when a page is executed, its outputs will be stored in a local database. This allows you to be sure that the outputs in your documentation are up-to-date, while saving time avoiding unnecessary re-execution. It also allows you to store your .ipynb files in your git repository without their outputs, but still leverage a cache to save time when building your site.

When you re-build your site, the following will happen:

  • Notebooks that have not seen changes to their code cells since the last build will not be re-executed. Instead, their outputs will be pulled from the cache and inserted into your site.

  • Notebooks that have any change to their code cells will be re-executed, and the cache will be updated with the new outputs.

By default, the cache will be placed in the parent of your build folder. Generally, this is in _build/.jupyter_cache.

You may also specify a path to the location of a jupyter cache you’d like to use:

jupyter_cache = path/to/mycache

The path should point to an empty folder, or a folder where a jupyter cache already exists.

Execution FAQs

How can I include code that raises errors?

In some cases, you may want to intentionally show code that doesn’t work (e.g., to show the error message). To do this, add a raises-exception tag to your code cell. This can be done via a Jupyter interface, or via the {code-cell} directive like so:

```{code-cell}
---
tags: [raises-exception]
---
print(thisvariabledoesntexist)
```

Which produces:

print(thisvariabledoesntexist)