A much faster version of nbstripout with a slightly different set of features, and autotrust notebooks local git configuration

This is a rewrite of nbstripout. It's much faster because it doesn't load any of the very heavy nbformat, and operates on the json file directly.

It's used in all fastai projects, and this repo was created to make it easy to re-use it in other projects, so all files are in one place.

This tool implements only a sub-set of nbstripout (most of it) and makes no attempt to neither be identical nor try to keep it in sync with nbstripout. It implements the parts we needed for fastai needs.

This repository's purpose is not to maintain a different implementation of nbstripout, but to make it easy to integrate the existing functionality into other fastai projects, since it involves quite a few files.

Therefore please submit no PRs or Issues unless you found a bug in the current implementation.

If you'd like to create and maintain a faster version of nbstripout with all the features it provides, please feel free to fork this implementation and build upon it.

1. The strip out tool itself is: tools/fastai-nbstripout

2. The helper tool tools/trust-origin-git-config autogenerates .gitconfig, which in turn configures the action of the git filters and tells git to trust this local config file. (git config --local include.path ../.gitconfig). Here is the usage instructions:

   tools/trust-origin-git-config -h
   usage: trust-origin-git-config [-h] [-e] [-d] [-t]
   
    optional arguments:
      -h, --help     show this help message and exit
      -e, --enable   Trust repo-wide .gitconfig (default action)
      -d, --disable  Distrust repo-wide .gitconfig
      -t, --test     Validate repo-wide .gitconfig config
   

   Therefore, to enable the setup, you run:

   tools/trust-origin-git-config -e
   

   and to disable:

   tools/trust-origin-git-config -d
   

   You will want to add .gitconfig to .gitignores, since it's autogenerated (the included in this repo .gitignores already does that).

3. Now, all that remains is to configure directories with jupyter notebooks to be stripped out. This is done via the .gitattributes file placed in the desired directories.

   Currently, fastai-nbstripout supports two stripout configurations:

   This .gitattributes will strip out all the unnecessary bits and keep the outputs:

   *.ipynb filter=fastai-nbstripout-code
   *.ipynb diff=ipynb-code
   

   You can see this setup and its effects under with-outputs directory.

   This .gitattributes will strip out all the unnecessary bits, including the outputs:

   *.ipynb filter=fastai-nbstripout-docs
   *.ipynb diff=ipynb-docs
   

   You can see this setup and its effects under without-outputs directory.

   These settings apply recursively to all sub-dirs.

You will need to git add all these files to your git repo before activating the setup.

Normally, modified outside of jupyter environment notebooks lose their "trusted" state, so you won't be able to run them automatically and will need to manually set them to be trusted. The following setup does it automatically for you on git pull.

1. Configure which directories you want to be "auto-trusted" by editing tools/trust-doc-nbs. E.g. in this sample project you will find:

   trust_nbs('without-outputs')
   trust_nbs('with-outputs')
   

2. tools/trust-doc-nbs is a hook that runs automatically on git pull, and tools/trust-doc-nb-install-hooks is the tool that configures that hook. So you need to run it once after git clone.

Who's going to remember all these tools to be run after git clone. That's why there is a wrapper tools/run-after-git-clone that runs all the other tools that configure git to do the right thing. And it's easy to remember. Of course, you don't have to use it and you can run each tool separately.

Every user, that needs to have these configured, has to run the configuration scripts manually once upon the first clone of the repository. Which sucks, because some users will forget and commit unstripped out notebooks.

Unfortunately, due to the way git security is set up, there is no other way to go about it. The only way to catch unstripped out notebook committed is to have server-side git hooks, but github doesn't allow those.

Change the instructions for your projects to include the local git setup. For example, for this project it'd become:

git clone https://github.com/fastai/fastai-nbstripout
cd fastai-nbstripout
tools/run-after-git-clone

The way I personally deal with me forgetting to run the local git setup is to always run git diff before git commit, it takes a few seconds and I catch my forgetfulness this way. If the output contains execution_count that is not null:

   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,

That means I don't have it configured.