Note: contributing implies licensing those contributions
under the terms of [COPYING](../COPYING), which is an MIT-like license.
## Opening issues
* Make sure you have a [GitHub account](https://github.com/signup/free)
* Make sure there is no open issue on the topic
* [Submit a new issue](https://github.com/NixOS/nixpkgs/issues/new/choose) by choosing the kind of topic and fill out the template
## Submitting changes
* Format the commit messages in the following way:
```
(pkg-name | nixos/<module>): (from -> to | init at version | refactor | etc)
(Motivation for change. Additional information.)
```
For consistency, there should not be a period at the end of the commit message's summary line (the first line of the commit message).
Examples:
* nginx: init at 2.0.1
* firefox: 54.0.1 -> 55.0
* nixos/hydra: add bazBaz option
Dual baz behavior is needed to do foo.
* nixos/nginx: refactor config generation
The old config generation system used impure shell scripts and could break in specific circumstances (see #1234).
*`meta.description` should:
* Be capitalized.
* Not start with the package name.
* Not have a period at the end.
*`meta.license` must be set and fit the upstream license.
* If there is no upstream license, `meta.license` should default to `stdenv.lib.licenses.unfree`.
*`meta.maintainers` must be set.
See the nixpkgs manual for more details on [standard meta-attributes](https://nixos.org/nixpkgs/manual/#sec-standard-meta-attributes) and on how to [submit changes to nixpkgs](https://nixos.org/nixpkgs/manual/#chap-submitting-changes).
## Writing good commit messages
In addition to writing properly formatted commit messages, it's important to include relevant information so other developers can later understand *why* a change was made. While this information usually can be found by digging code, mailing list/Discourse archives, pull request discussions or upstream changes, it may require a lot of work.
For package version upgrades and such a one-line commit message is usually sufficient.
Follow these steps to backport a change into a release branch in compliance with the [commit policy](https://nixos.org/nixpkgs/manual/#submitting-changes-stable-release-branches).
3. Create a branch for your change, e.g. `git checkout -b backport`.
4. When the reason to backport is not obvious from the original commit message, use `git cherry-pick -xe <original commit>` and add a reason. Otherwise use `git cherry-pick -x <original commit>`. That's fine for minor version updates that only include security and bug fixes, commits that fixes an otherwise broken package or similar.
5. Push to GitHub and open a backport pull request. Make sure to select the release branch (e.g. `release-20.03`) as the target branch of the pull request, and link to the pull request in which the original change was comitted to `master`. The pull request title should be the commit title with the release version as prefix, e.g. `[20.03]`.
