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Add section on fetching sources

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Edward Tjörnhammar 2015-04-29 22:02:13 +02:00
parent 949746f9f5
commit 2bf516613d

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@ -598,6 +598,51 @@ evaluate correctly.</para>
</section>
</section>
<section xml:id="sec-sources"><title>Fetching Sources</title>
<para>There are multiple ways to fetch a package source in nixpkgs. The
general guidline is that you should package sources with a high degree of
availability. Right now there is only one fetcher which has mirroring
support and that is <literal>fetchurl</literal>. Note that you should also
prefer protocols which have a corresponding proxy environment variable.
</para>
<para>You can find many source fetch helpers in <literal>pkgs/build-support/fetch*</literal>.
</para>
<para>In the file <literal>pkgs/top-level/all-packages.nix</literal> you can
find fetch helpers, these have names on the form
<literal>fetchFrom*</literal>. The intention of these are to provide
snapshot fetches but using the same api as some of the version controlled
fetchers from <literal>pkgs/build-support/</literal>. As an example going
from bad to good:
<itemizedlist>
<listitem><para>Uses <literal>git://</literal> which won't be proxied.
<programlisting>
src = fetchgit {
url = "git://github.com/NixOS/nix.git";
rev = "1f795f9f44607cc5bec70d1300150bfefcef2aae";
sha256 = "1cw5fszffl5pkpa6s6wjnkiv6lm5k618s32sp60kvmvpy7a2v9kg";
}
</programlisting></para>
</listitem>
<listitem><para>This is ok, but an archive fetch will still be faster.
<programlisting>
src = fetchgit {
url = "https://github.com/NixOS/nix.git";
rev = "1f795f9f44607cc5bec70d1300150bfefcef2aae";
sha256 = "1cw5fszffl5pkpa6s6wjnkiv6lm5k618s32sp60kvmvpy7a2v9kg";
}
</programlisting></para>
</listitem>
<listitem><para>Fetches a snapshot archive and you get the rev you want.
<programlisting>
src = fetchFromGitHub {
owner = "NixOS";
repo = "nix";
rev = "1f795f9f44607cc5bec70d1300150bfefcef2aae";
sha256 = "04yri911rj9j19qqqn6m82266fl05pz98inasni0vxr1cf1gdgv9";
}
</programlisting></para>
</listitem>
</itemizedlist>
</para>
</section>
</chapter>