# How to contribute

We definitely welcome your patches and contributions to gRPC!

If you are new to github, please start by reading [Pull Request
howto](https://help.github.com/articles/about-pull-requests/)

## Legal requirements

In order to protect both you and ourselves, you will need to sign the
[Contributor License
Agreement](https://identity.linuxfoundation.org/projects/cncf).

## Cloning the repository

Before starting any development work you will need a local copy of the gRPC repository.
Please follow the instructions in [Building gRPC C++: Clone the repository](BUILDING.md#clone-the-repository-including-submodules).

## Building & Running tests

Different languages use different build systems. To hide the complexity
of needing to build with many different build systems, a portable python
script that unifies the experience of building and testing gRPC in different
languages and on different platforms is provided.

To build gRPC in the language of choice (e.g. `c++`, `csharp`, `php`, `python`, `ruby`, ...)
- Prepare your development environment based on language-specific instructions in `src/YOUR-LANGUAGE` directory.
- The language-specific instructions might involve installing C/C++ prerequisites listed in
  [Building gRPC C++: Prerequisites](BUILDING.md#pre-requisites). This is because gRPC implementations
  in this repository are using the native gRPC "core" library internally.
- Run
  ```
  python tools/run_tests/run_tests.py -l YOUR_LANGUAGE --build_only
  ```
- To also run all the unit tests after building
  ```
  python tools/run_tests/run_tests.py -l YOUR_LANGUAGE
  ```

You can also run `python tools/run_tests/run_tests.py --help` to discover useful command line flags supported. For more details,
see [tools/run_tests](tools/run_tests) where you will also find guidance on how to run various other test suites (e.g. interop tests, benchmarks).

## Generated project files

To ease maintenance of language- and platform- specific build systems, many
projects files are generated using templates and should not be edited by hand.
Run `tools/buildgen/generate_projects.sh` to regenerate.  See
[templates](templates) for details.

As a rule of thumb, if you see the "sanity tests" failing you've most likely
edited generated files or you didn't regenerate the projects properly (or your
code formatting doesn't match our code style).

## Guidelines for Pull Requests
How to get your contributions merged smoothly and quickly.
 
- Create **small PRs** that are narrowly focused on **addressing a single
  concern**.  We often times receive PRs that are trying to fix several things
  at a time, but only one fix is considered acceptable, nothing gets merged and
  both author's & review's time is wasted.  Create more PRs to address different
  concerns and everyone will be happy.
 
- For speculative changes, consider opening an issue and discussing it first.
  If you are suggesting a behavioral or API change, consider starting with a
  [gRFC proposal](https://github.com/grpc/proposal).
 
- Provide a good **PR description** as a record of **what** change is being made
  and **why** it was made.  Link to a GitHub issue if it exists.
 
- Don't fix code style and formatting unless you are already changing that line
  to address an issue.  PRs with irrelevant changes won't be merged.  If you do
  want to fix formatting or style, do that in a separate PR.
 
- Unless your PR is trivial, you should expect there will be reviewer comments
  that you'll need to address before merging.  We expect you to be reasonably
  responsive to those comments, otherwise the PR will be closed after 2-3 weeks
  of inactivity.

- If you have non-trivial contributions, please consider adding an entry to [the
  AUTHORS file](https://github.com/grpc/grpc/blob/master/AUTHORS) listing the
  copyright holder for the contribution (yourself, if you are signing the
  individual CLA, or your company, for corporate CLAs) in the same PR as your
  contribution.  This needs to be done only once, for each company, or
  individual.
 
- Maintain **clean commit history** and use **meaningful commit messages**.
  PRs with messy commit history are difficult to review and won't be merged.
  Use `rebase -i upstream/master` to curate your commit history and/or to
  bring in latest changes from master (but avoid rebasing in the middle of
  a code review).
 
- Keep your PR up to date with upstream/master (if there are merge conflicts,
  we can't really merge your change).
 
- If you are regenerating the projects using
  `tools/buildgen/generate_projects.sh`, make changes to generated files a
  separate commit with commit message `regenerate projects`.  Mixing changes
  to generated and hand-written files make your PR difficult to review.
  Note that running this script requires the installation of Python packages
  `pyyaml` and `mako` (typically installed using `pip`) as well as a recent
  version of [`go`](https://golang.org/doc/install#install).
 
- **All tests need to be passing** before your change can be merged.
  We recommend you **run tests locally** before creating your PR to catch
  breakages early on (see [tools/run_tests](tools/run_tests).  Ultimately, the
  green signal will be provided by our testing infrastructure.  The reviewer
  will help you if there are test failures that seem not related to the change
  you are making.
 
- Exceptions to the rules can be made if there's a compelling reason for doing
  so.