Skip to content

cruft

cruft allows you to maintain all the necessary boilerplate for packaging and building projects separate from the code you intentionally write. Fully compatible with existing Cookiecutter templates.

Many project template utilities exist that automate the copying and pasting of code to create new projects. This seems great! However, once created, most leave you with that copy-and-pasted code to manage through the life of your project.

Key Features

Cookiecutter Compatible
cruft utilizes Cookiecutter as its template expansion engine. Meaning it retains full compatibility with all existing Cookiecutter templates.
Template Validation
cruft can quickly validate whether or not a project is using the latest version of a template using cruft check. This check can easily be added to CI pipelines to ensure your projects stay in-sync.
Automatic Template Updates
cruft automates the process of updating code to match the latest version of a template, making it easy to utilize template improvements across many projects.

Installation

pip install cruft

Usage

Creating a New Project

To create a new project using cruft run cruft create PROJECT_URL from the command line.

cruft will then ask you any necessary questions to create your new project. It will use your answers to expand the provided template, and then return the directory it placed the expanded project.

Behind the scenes, cruft uses Cookiecutter to do the project expansion. The only difference in the resulting output is a .cruft.json file that contains the git hash of the template used as well as the parameters specified.

Updating a Project

To update an existing project, that was created using cruft, run cruft update in the root of the project.

If there are any updates, cruft will have you review them before applying. If you accept the changes cruft will apply them to your project and update the .cruft.json file for you.

Sometimes certain files just aren't good fits for updating. Such as test cases or __init__ files. You can tell cruft to always skip updating these files on a project by project basis by added them to a skip section within your .cruft.json file:

{
    "template": "https://github.com/timothycrosley/cookiecutter-python",
    "commit": "8a65a360d51250221193ed0ec5ed292e72b32b0b",
    "skip": [
        "cruft/__init__.py",
        "tests"
    ],
    ...
}

Or, if you have toml installed, you can add skip files directly to a tool.cruft section of your pyproject.toml file:

[tool.cruft]
skip = ["cruft/__init__.py", "tests"]

Checking a Project

Checking to see if a project is missing a template update is as easy as running cruft check. If the project is out-of-date an error and exit code 1 will be returned.

cruft check can be added to CI pipelines to ensure projects don't unintentionally drift.

Linking an Existing Project

Have an existing project that you created from a template in the past using Cookiecutter directly? You can link it to the template that was used to create it using: cruft link TEMPLATE_REPOSITORY.

You can then specify the last commit of the template the project has been updated to be consistent with, or accept the default of using the latest commit from the template.

Compute the diff

With time, your boilerplate may end up being very different from the actual cookiecutter template. Cruft allows you to quickly see what changed in your local project compared to the template. It is as easy as running cruft diff. If any local file differs from the template, the diff will appear in your terminal in a similar fashion to git diff.

The cruft diff command optionally accepts an --exit-code flag that will make cruft exit with a non-0 code should any diff is found. You can combine this flag with the skip section of your .cruft.json to make stricter CI checks that ensures any improvement to the template is always submitted upstream.

Issues

Error: Unable to interpret changes between current project and cookiecutter template as unicode.

Typically a result of hidden binary files in project folder. Maybe you have a hook that initializes the .git directory. Since 2.10.0 you can add a skip category inside the .cruft.json, so that it doesn't check that directory:

{
  "template": "xxx",
  "commit": "xxx",
  "checkout": null,
  "context": {
    "cookiecutter": {
       ...
    }
  },
  "directory": null,
  "skip": [
    ".git"
  ]
}

References


Last update: 2022-06-08