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Identify unused dependencies and avoid a bloated virtual environment.

πŸŒ€ Migration guide: creosote 2.x to 3.x

Expand me to read the guide.

Creosote was updated to 3.0.0 because the way arguments were supplied has now changed. This also brings pyproject.toml configuration support.

Argument name change

The argument naming has changed:

2.x argument name 3.x argument name
--exclude-deps --exclude-dep
--paths --path
--sections --section

Multiple argument values

With creosote 2.x, you were able to provide multiple values following some arguments, example:

creosote -p

With creosote 3.x, you must now provide multiple arguments as a key/value pair:

creosote -p -p

This new creosote 3.x behavior applies to the following 3.x CLI arguments:

  • --venv
  • --exclude-dep
  • -p or --path
  • -s or --section

⚑️ Quickstart

Install creosote in separate virtual environment (using e.g. pipx):

pipx install creosote

Scan virtual environment for unused dependencies (PEP-621 example below, but Poetry, Pipenv, PDM and requirements.txt files are also supported, see this table):

$ creosote
Found dependencies in pyproject.toml: dotty-dict, loguru, pip-requirements-parser, requests, toml
Oh no, bloated venv! 🀒 πŸͺ£
Unused dependencies found: requests

And after having removed/uninstalled requests:

$ creosote
Found dependencies in pyproject.toml: dotty-dict, loguru, pip-requirements-parser, toml
No unused dependencies found! ✨

βœ‹ Note that you will likely not be able to run creosote as-is, but will have to configure it so it understands your project structure.

Get help:

creosote --help

βš™οΈ Configuration

You can configure creosote using commandline arguments or in your pyproject.toml.

Using commandline arguments

Required arguments

Argument Default value Description
--venv Path to activated virtual environment or .venv The path(s) to your virtual environment or site-packages folder.
--path src The path(s) to your source code, one or more files/folders.
--deps-file pyproject.toml The path to the file specifying your dependencies, like pyproject.toml, requirements_*.txt | .in.
--section project.dependencies The toml section(s) to parse, e.g. project.dependencies.

Optional arguments

Argument Default value Description
--exclude-dep Dependencies you wish to not scan for.
--format default The output format, valid values are default, no-color or porcelain.

Using pyproject.toml

exclude-deps =[

πŸ€” How this works

The creosote tool will first scan the given python file(s) for all its imports. Then it fetches all dependency names (from the dependencies spec file). Finally, all imports are associated with their corresponding dependency name (requires the virtual environment for resolving and the ability to read the dependency's RECORD or top_level.txt file). If a dependency does not have any imports associated, it is considered unused.

See the main function in for a terse overview of the logic.

🌢️ Features

These optional features enable new/experimental functionality, that may be backward incompatible and may be removed/changed at any time. Some features may become mandatory for a target release version e.g. the next major release. Enable using --use-feature <FEATURE>. Use at your own risk!

Feature Description Target version
fail-excluded-and-not-installed When excluding a dependency from the scan (using --exclude-dep) and if the dependency is removed from the dependency specification file (e.g. pyproject.toml), return with exit code 1. N/A

😀 Known limitations

  • importlib imports are not detected by the AST parser (a great first contribution for anyone inclined πŸ˜„, reach out or start looking at

πŸ₯§ History and ambition

This project was inspired by security vulnerability reports about production dependencies that were shipped into production but turned out to be unused. Creosote aims to help prevent such occurrences and reduce noise from bots like Dependabot or Renovate for simply unused dependencies.

The intent is to run Creosote in CI (or with pre-commit) to detect cases where developers forget to remove unused dependencies, especially during refactorings. Creosote can identify both unused production dependencies and developer dependencies, depending on your objectives.


Which dependency specification tooling/standards are supported?

Tool/standard Supported --deps-file value Example --section values
PDM and PEP-582 βœ… pyproject.toml project.dependencies,
Pipenv βœ… pyproject.toml packages,
Poetry βœ… pyproject.toml tool.poetry.dependencies, (legacy),<GROUP>.dependencies
Legacy Setuptools ( ❌
PEP-508 (requirements.txt, pip-tools) βœ… *.[txt|in] N/A
PEP-621 βœ… pyproject.toml project.dependencies,

πŸ“” Notes on PEP-508 (requirements.txt)

When using requirements.txt files to specify dependencies, there is no way to tell which part of requirements.txt specifies production vs developer dependencies. Therefore, you have to break your requirements.txt file into e.g. requirements-prod.txt and requirements-dev.txt and use any of them as input. When using pip-tools, you likely want to point Creosote to scan your *.in file(s).

πŸ““ Notes on PEP-582 (__pypackages__)

Creosote supports the __pypackages__ folder, although PEP-582 was rejected. There is no reason to remove support for this today, but in case supporting this becomes cumbersome in the future, supporting PEP-582 might be dropped.

creosote --venv __pypackages__

Can I specify multiple toml sections?

Yes, you can specify a list of sections after the --section argument. It all depends on what your setup looks like and what you set out to achieve.

$ creosote --section project.dependencies --section project.optional-dependencies.lint --section project.optional-dependencies.test

Can I exclude dependencies from the scan?

Yes, you can use the --exclude-dep argument to specify one or more dependencies you do not wish to get warnings for.

This feature is intended for dependencies you must specify in your dependencies spec file, but which you don't import in your source code. An example of such a dependency are database drivers, which are commonly only defined in connection strings and will signal to the ORM which driver to use.

$ creosote --exclude-dep pyodbc --exclude-dep pg8000

Can I run Creosote in a GitHub Action workflow?

Yes, please see the action job example in .github/workflows/test.yml.

Can I run Creosote with pre-commit?

Yes, see example in .pre-commit-config.yaml.

Here's another example setup, if already have Creosote installed onto $PATH (via e.g. pipx).
# .pre-commit-config.yaml

  - repo: local
      - id: system
        name: creosote
        entry: creosote --venv .venv --path src --deps-file pyproject.toml --section project.dependencies
        pass_filenames: false
        files: \.(py|toml|txt|in|lock)$
        language: system

What's with the name "creosote"?

This tool has borrowed its name from the Monty Python scene about Mr. Creosote.

πŸ“° Creosote in the "news"

Because it makes me happy to see this tool can help others! πŸ₯°

πŸ‘©β€πŸ”¬ Development/debugging info

Install in-development builds

You can run in-development versions of Creosote. Examples below:

# Creosote build from main branch
$ pipx install --suffix=@main --force git+
$ creosote@main --venv .venv ...
$ pipx uninstall creosote@main

# Creosote build from PR #123
$ pipx install --suffix=@123 --force git+
$ creosote@123 --venv .venv ...
$ pipx uninstall creosote@123

You can also clone down the repo and run creosote from the git repo:

$ python -m venv .venv
$ source .venv/bin/activate  # linux/macOS syntax
$ pip install -e '.[dev]'  # install the dependencies group 'dev'
$ creosote -venv .venv ...

πŸš€ Releasing

  1. Bump version in src/creosote/ and .pre-commit-config.yaml.
  2. GitHub Action will run automatically on creating a release and deploy the release onto PyPi.