nixpkgs/doc/submitting-changes.xml
2018-05-01 19:54:21 -04:00

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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-submitting-changes">
<title>Submitting changes</title>
<section>
<title>Making patches</title>
<itemizedlist>
<listitem>
<para>
Read <link xlink:href="https://nixos.org/nixpkgs/manual/">Manual (How to
write packages for Nix)</link>.
</para>
</listitem>
<listitem>
<para>
Fork the repository on GitHub.
</para>
</listitem>
<listitem>
<para>
Create a branch for your future fix.
<itemizedlist>
<listitem>
<para>
You can make branch from a commit of your local
<command>nixos-version</command>. That will help you to avoid
additional local compilations. Because you will receive packages from
binary cache.
<itemizedlist>
<listitem>
<para>
For example: <command>nixos-version</command> returns
<command>15.05.git.0998212 (Dingo)</command>. So you can do:
</para>
</listitem>
</itemizedlist>
<screen>
$ git checkout 0998212
$ git checkout -b 'fix/pkg-name-update'
</screen>
</para>
</listitem>
<listitem>
<para>
Please avoid working directly on the <command>master</command> branch.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
Make commits of logical units.
<itemizedlist>
<listitem>
<para>
If you removed pkgs, made some major NixOS changes etc., write about
them in
<command>nixos/doc/manual/release-notes/rl-unstable.xml</command>.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
Check for unnecessary whitespace with <command>git diff --check</command>
before committing.
</para>
</listitem>
<listitem>
<para>
Format the commit in a following way:
</para>
<programlisting>
(pkg-name | nixos/&lt;module>): (from -> to | init at version | refactor | etc)
Additional information.
</programlisting>
<itemizedlist>
<listitem>
<para>
Examples:
<itemizedlist>
<listitem>
<para>
<command>nginx: init at 2.0.1</command>
</para>
</listitem>
<listitem>
<para>
<command>firefox: 54.0.1 -> 55.0</command>
</para>
</listitem>
<listitem>
<para>
<command>nixos/hydra: add bazBaz option</command>
</para>
</listitem>
<listitem>
<para>
<command>nixos/nginx: refactor config generation</command>
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
Test your changes. If you work with
<itemizedlist>
<listitem>
<para>
nixpkgs:
<itemizedlist>
<listitem>
<para>
update pkg ->
<itemizedlist>
<listitem>
<para>
<command>nix-env -i pkg-name -f &lt;path to your local nixpkgs
folder&gt;</command>
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
add pkg ->
<itemizedlist>
<listitem>
<para>
Make sure it's in
<command>pkgs/top-level/all-packages.nix</command>
</para>
</listitem>
<listitem>
<para>
<command>nix-env -i pkg-name -f &lt;path to your local nixpkgs
folder&gt;</command>
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
<emphasis>If you don't want to install pkg in you
profile</emphasis>.
<itemizedlist>
<listitem>
<para>
<command>nix-build -A pkg-attribute-name &lt;path to your local
nixpkgs folder&gt;/default.nix</command> and check results in the
folder <command>result</command>. It will appear in the same
directory where you did <command>nix-build</command>.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
If you did <command>nix-env -i pkg-name</command> you can do
<command>nix-env -e pkg-name</command> to uninstall it from your
system.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
NixOS and its modules:
<itemizedlist>
<listitem>
<para>
You can add new module to your NixOS configuration file (usually
it's <command>/etc/nixos/configuration.nix</command>). And do
<command>sudo nixos-rebuild test -I nixpkgs=&lt;path to your local
nixpkgs folder&gt; --fast</command>.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
If you have commits <command>pkg-name: oh, forgot to insert
whitespace</command>: squash commits in this case. Use <command>git rebase
-i</command>.
</para>
</listitem>
<listitem>
<para>
Rebase you branch against current <command>master</command>.
</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Submitting changes</title>
<itemizedlist>
<listitem>
<para>
Push your changes to your fork of nixpkgs.
</para>
</listitem>
<listitem>
<para>
Create pull request:
<itemizedlist>
<listitem>
<para>
Write the title in format <command>(pkg-name | nixos/&lt;module>):
improvement</command>.
<itemizedlist>
<listitem>
<para>
If you update the pkg, write versions <command>from -> to</command>.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
Write in comment if you have tested your patch. Do not rely much on
<command>TravisCI</command>.
</para>
</listitem>
<listitem>
<para>
If you make an improvement, write about your motivation.
</para>
</listitem>
<listitem>
<para>
Notify maintainers of the package. For example add to the message:
<command>cc @jagajaga @domenkozar</command>.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Pull Request Template</title>
<para>
The pull request template helps determine what steps have been made for a
contribution so far, and will help guide maintainers on the status of a
change. The motivation section of the PR should include any extra details
the title does not address and link any existing issues related to the pull
request.
</para>
<para>
When a PR is created, it will be pre-populated with some checkboxes detailed
below:
</para>
<section>
<title>Tested using sandboxing</title>
<para>
When sandbox builds are enabled, Nix will setup an isolated environment for
each build process. It is used to remove further hidden dependencies set by
the build environment to improve reproducibility. This includes access to
the network during the build outside of <function>fetch*</function>
functions and files outside the Nix store. Depending on the operating
system access to other resources are blocked as well (ex. inter process
communication is isolated on Linux); see
<link
xlink:href="https://nixos.org/nix/manual/#description-45">build-use-sandbox</link>
in Nix manual for details.
</para>
<para>
Sandboxing is not enabled by default in Nix due to a small performance hit
on each build. In pull requests for
<link
xlink:href="https://github.com/NixOS/nixpkgs/">nixpkgs</link>
people are asked to test builds with sandboxing enabled (see
<literal>Tested using sandboxing</literal> in the pull request template)
because
in<link
xlink:href="https://nixos.org/hydra/">https://nixos.org/hydra/</link>
sandboxing is also used.
</para>
<para>
Depending if you use NixOS or other platforms you can use one of the
following methods to enable sandboxing
<emphasis role="bold">before</emphasis> building the package:
<itemizedlist>
<listitem>
<para>
<emphasis role="bold">Globally enable sandboxing on NixOS</emphasis>:
add the following to <filename>configuration.nix</filename>
<screen>nix.useSandbox = true;</screen>
</para>
</listitem>
<listitem>
<para>
<emphasis role="bold">Globally enable sandboxing on non-NixOS
platforms</emphasis>: add the following to:
<filename>/etc/nix/nix.conf</filename>
<screen>build-use-sandbox = true</screen>
</para>
</listitem>
</itemizedlist>
</para>
</section>
<section>
<title>Built on platform(s)</title>
<para>
Many Nix packages are designed to run on multiple platforms. As such, it's
important to let the maintainer know which platforms your changes have been
tested on. It's not always practical to test a change on all platforms, and
is not required for a pull request to be merged. Only check the systems you
tested the build on in this section.
</para>
</section>
<section>
<title>Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)</title>
<para>
Packages with automated tests are much more likely to be merged in a timely
fashion because it doesn't require as much manual testing by the maintainer
to verify the functionality of the package. If there are existing tests for
the package, they should be run to verify your changes do not break the
tests. Tests only apply to packages with NixOS modules defined and can only
be run on Linux. For more details on writing and running tests, see the
<link
xlink:href="https://nixos.org/nixos/manual/index.html#sec-nixos-tests">section
in the NixOS manual</link>.
</para>
</section>
<section>
<title>Tested compilation of all pkgs that depend on this change using <command>nox-review</command></title>
<para>
If you are updating a package's version, you can use nox to make sure all
packages that depend on the updated package still compile correctly. This
can be done using the nox utility. The <command>nox-review</command>
utility can look for and build all dependencies either based on uncommited
changes with the <literal>wip</literal> option or specifying a github pull
request number.
</para>
<para>
review uncommitted changes:
<screen>nix-shell -p nox --run "nox-review wip"</screen>
</para>
<para>
review changes from pull request number 12345:
<screen>nix-shell -p nox --run "nox-review pr 12345"</screen>
</para>
</section>
<section>
<title>Tested execution of all binary files (usually in <filename>./result/bin/</filename>)</title>
<para>
It's important to test any executables generated by a build when you change
or create a package in nixpkgs. This can be done by looking in
<filename>./result/bin</filename> and running any files in there, or at a
minimum, the main executable for the package. For example, if you make a
change to <package>texlive</package>, you probably would only check the
binaries associated with the change you made rather than testing all of
them.
</para>
</section>
<section>
<title>Meets nixpkgs contribution standards</title>
<para>
The last checkbox is fits
<link
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/.github/CONTRIBUTING.md">CONTRIBUTING.md</link>.
The contributing document has detailed information on standards the Nix
community has for commit messages, reviews, licensing of contributions you
make to the project, etc... Everyone should read and understand the
standards the community has for contributing before submitting a pull
request.
</para>
</section>
</section>
<section>
<title>Hotfixing pull requests</title>
<itemizedlist>
<listitem>
<para>
Make the appropriate changes in you branch.
</para>
</listitem>
<listitem>
<para>
Don't create additional commits, do
<itemizedlist>
<listitem>
<para>
<command>git rebase -i</command>
</para>
</listitem>
<listitem>
<para>
<command>git push --force</command> to your branch.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Commit policy</title>
<itemizedlist>
<listitem>
<para>
Commits must be sufficiently tested before being merged, both for the
master and staging branches.
</para>
</listitem>
<listitem>
<para>
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.
</para>
</listitem>
<listitem>
<para>
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.
</para>
</listitem>
</itemizedlist>
<section>
<title>Master branch</title>
<itemizedlist>
<listitem>
<para>
It should only see non-breaking commits that do not cause mass rebuilds.
</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Staging branch</title>
<itemizedlist>
<listitem>
<para>
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.
<link xlink:href="http://comments.gmane.org/gmane.linux.distributions.nixos/13447">Read
policy here</link>.
</para>
</listitem>
<listitem>
<para>
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.
<link xlink:href="http://hydra.nixos.org/jobset/nixpkgs/staging#tabs-evaluations">Keep
an eye on the staging evaluations here</link>. If any fixes for staging
happen to be already in master, then master can be merged into staging.
</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Stable release branches</title>
<itemizedlist>
<listitem>
<para>
If you're cherry-picking a commit to a stable release branch, always use
<command>git cherry-pick -xe</command> and ensure the message contains a
clear description about why this needs to be included in the stable
branch.
</para>
<para>
An example of a cherry-picked commit would look like this:
</para>
<screen>
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.
</screen>
</listitem>
</itemizedlist>
</section>
</section>
</chapter>