Read Manual (How to write packages for Nix). Fork the repository on GitHub. Create a branch for your future fix. You can make branch from a commit of your local nixos-version. That will help you to avoid additional local compilations. Because you will receive packages from binary cache. For example: nixos-version returns 15.05.git.0998212 (Dingo). So you can do: $ git checkout 0998212 $ git checkout -b 'fix/pkg-name-update' Please avoid working directly on the master branch. Make commits of logical units. If you removed pkgs, made some major NixOS changes etc., write about them in nixos/doc/manual/release-notes/rl-unstable.xml. Check for unnecessary whitespace with git diff --check before committing. Format the commit in a following way: (pkg-name | service-name): (from -> to | init at version | refactor | etc) Additional information. Examples: nginx: init at 2.0.1 firefox: 3.0 -> 3.1.1 hydra service: add bazBaz option nginx service: refactor config generation Test your changes. If you work with nixpkgs: update pkg -> nix-env -i pkg-name -f <path to your local nixpkgs folder> add pkg -> Make sure it's in pkgs/top-level/all-packages.nix nix-env -i pkg-name -f <path to your local nixpkgs folder> If you don't want to install pkg in you profile. nix-build -A pkg-attribute-name <path to your local nixpkgs folder>/default.nix and check results in the folder result. It will appear in the same directory where you did nix-build. If you did nix-env -i pkg-name you can do nix-env -e pkg-name to uninstall it from your system. NixOS and its modules: You can add new module to your NixOS configuration file (usually it's /etc/nixos/configuration.nix). And do sudo nixos-rebuild test -I nixpkgs=<path to your local nixpkgs folder> --fast. If you have commits pkg-name: oh, forgot to insert whitespace: squash commits in this case. Use git rebase -i. Rebase you branch against current master.

Push your changes to your fork of nixpkgs. Create pull request: Write the title in format (pkg-name | service): improvement. If you update the pkg, write versions from -> to. Write in comment if you have tested your patch. Do not rely much on TravisCI. If you make an improvement, write about your motivation. Notify maintainers of the package. For example add to the message: cc @jagajaga @domenkozar.

Make the appropriate changes in you branch. Don't create additional commits, do git rebase -i git push --force to your branch.

Commits must be sufficiently tested before being merged, both for the master and staging branches. Hydra builds for master and staging should not be used as testing platform, it's a build farm for changes that have been already tested. When changing the bootloader installation process, extra care must be taken. Grub installations cannot be rolled back, hence changes may break people's installations forever. For any non-trivial change to the bootloader please file a PR asking for review, especially from @edolstra.

It should only see non-breaking commits that do not cause mass rebuilds.

It's only for non-breaking mass-rebuild commits. That means it's not to be used for testing, and changes must have been well tested already. Read policy here. If the branch is already in a broken state, please refrain from adding extra new breakages. Stabilize it for a few days, merge into master, then resume development on staging. Keep an eye on the staging evaluations here. If any fixes for staging happen to be already in master, then master can be merged into staging.

If you're cherry-picking a commit to a stable release branch, always use git cherry-pick -xe and ensure the message contains a clear description about why this needs to be included in the stable branch. An example of a cherry-picked commit would look like this: nixos: Refactor the world. The original commit message describing the reason why the world was torn apart. (cherry picked from commit abcdef) Reason: I just had a gut feeling that this would also be wanted by people from the stone age.