Hi there! Thank you for even being interested in contributing to LangChain. As an open source project in a rapidly developing field, we are extremely open to contributions, whether they be in the form of new features, improved infra, better documentation, or bug fixes.
To contribute to this project, please follow a "fork and pull request" workflow. Please do not try to push directly to this repo unless you are maintainer.
Please follow the checked-in pull request template when opening pull requests. Note related issues and tag relevant maintainers.
Pull requests cannot land without passing the formatting, linting and testing checks first. See Common Tasks for how to run these checks locally.
It's essential that we maintain great documentation and testing. If you:
- Fix a bug
- Add a relevant unit or integration test when possible. These live in
tests/unit_tests
andtests/integration_tests
.
- Add a relevant unit or integration test when possible. These live in
- Make an improvement
- Update any affected example notebooks and documentation. These lives in
docs
. - Update unit and integration tests when relevant.
- Update any affected example notebooks and documentation. These lives in
- Add a feature
- Add a demo notebook in
docs/modules
. - Add unit and integration tests.
- Add a demo notebook in
We're a small, building-oriented team. If there's something you'd like to add or change, opening a pull request is the best way to get our attention.
Our issues page is kept up to date with bugs, improvements, and feature requests.
There is a taxonomy of labels to help with sorting and discovery of issues of interest. Please use these to help organize issues.
If you start working on an issue, please assign it to yourself.
If you are adding an issue, please try to keep it focused on a single, modular bug/improvement/feature. If two issues are related, or blocking, please link them rather than combining them.
We will try to keep these issues as up to date as possible, though with the rapid rate of develop in this field some may get out of date. If you notice this happening, please let us know.
Our goal is to have the simplest developer setup possible. Should you experience any difficulty getting setup, please contact a maintainer! Not only do we want to help get you unblocked, but we also want to make sure that the process is smooth for future contributors.
In a similar vein, we do enforce certain linting, formatting, and documentation standards in the codebase. If you are finding these difficult (or even just annoying) to work with, feel free to contact a maintainer for help - we do not want these to get in the way of getting good code into the codebase.
This project uses Poetry as a dependency manager. Check out Poetry's documentation on how to install it on your system before proceeding.
❗Note: If you use Conda
or Pyenv
as your environment / package manager, avoid dependency conflicts by doing the following first:
- Before installing Poetry, create and activate a new Conda env (e.g.
conda create -n langchain python=3.9
) - Install Poetry (see above)
- Tell Poetry to use the virtualenv python environment (
poetry config virtualenvs.prefer-active-python true
) - Continue with the following steps.
To install requirements:
poetry install -E all
This will install all requirements for running the package, examples, linting, formatting, tests, and coverage. Note the -E all
flag will install all optional dependencies necessary for integration testing.
❗Note: If you're running Poetry 1.4.1 and receive a WheelFileValidationError
for debugpy
during installation, you can try either downgrading to Poetry 1.4.0 or disabling "modern installation" (poetry config installer.modern-installation false
) and re-install requirements. See this debugpy
issue for more details.
Now, you should be able to run the common tasks in the following section. To double check, run make test
, all tests should pass. If they don't you may need to pip install additional dependencies, such as numexpr
and openapi_schema_pydantic
.
Type make
for a list of common tasks.
Formatting for this project is done via a combination of Black and isort.
To run formatting for this project:
make format
Linting for this project is done via a combination of Black, isort, flake8, and mypy.
To run linting for this project:
make lint
We recognize linting can be annoying - if you do not want to do it, please contact a project maintainer, and they can help you with it. We do not want this to be a blocker for good code getting contributed.
Code coverage (i.e. the amount of code that is covered by unit tests) helps identify areas of the code that are potentially more or less brittle.
To get a report of current coverage, run the following:
make coverage
Langchain relies heavily on optional dependencies to keep the Langchain package lightweight.
If you're adding a new dependency to Langchain, assume that it will be an optional dependency, and that most users won't have it installed.
Users that do not have the dependency installed should be able to import your code without any side effects (no warnings, no errors, no exceptions).
To introduce the dependency to the pyproject.toml file correctly, please do the following:
- Add the dependency to the main group as an optional dependency
poetry add --optional [package_name]
- Open pyproject.toml and add the dependency to the
extended_testing
extra - Relock the poetry file to update the extra.
poetry lock --no-update
- Add a unit test that the very least attempts to import the new code. Ideally the unit test makes use of lightweight fixtures to test the logic of the code.
- Please use the
@pytest.mark.requires(package_name)
decorator for any tests that require the dependency.
See section about optional dependencies.
Unit tests cover modular logic that does not require calls to outside APIs.
To run unit tests:
make test
To run unit tests in Docker:
make docker_tests
If you add new logic, please add a unit test.
Integration tests cover logic that requires making calls to outside APIs (often integration with other services).
warning Almost no tests should be integration tests.
Tests that require making network connections make it difficult for other developers to test the code.
Instead favor relying on responses
library and/or mock.patch to mock
requests using small fixtures.
To run integration tests:
make integration_tests
If you add support for a new external API, please add a new integration test.
If you are adding a Jupyter notebook example, you'll want to install the optional dev
dependencies.
To install dev dependencies:
poetry install --with dev
Launch a notebook:
poetry run jupyter notebook
When you run poetry install
, the langchain
package is installed as editable in the virtualenv, so your new logic can be imported into the notebook.
Docs are largely autogenerated by sphinx from the code.
For that reason, we ask that you add good documentation to all classes and methods.
Similar to linting, we recognize documentation can be annoying. If you do not want to do it, please contact a project maintainer, and they can help you with it. We do not want this to be a blocker for good code getting contributed.
Before building the documentation, it is always a good idea to clean the build directory:
make docs_clean
Next, you can run the linkchecker to make sure all links are valid:
make docs_linkcheck
Finally, you can build the documentation as outlined below:
make docs_build
As of now, LangChain has an ad hoc release process: releases are cut with high frequency by a developer and published to PyPI.
LangChain follows the semver versioning standard. However, as pre-1.0 software, even patch releases may contain non-backwards-compatible changes.
If your contribution has made its way into a release, we will want to give you credit on Twitter (only if you want though)! If you have a Twitter account you would like us to mention, please let us know in the PR or in another manner.