nixpkgs/doc/functions/prefer-remote-fetch.xml

<section xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/xinclude"
         xml:id="sec-prefer-remote-fetch">
 <title>prefer-remote-fetch overlay</title>

 <para>
  <function>prefer-remote-fetch</function> is an overlay that download sources
  on remote builder. This is useful when the evaluating machine has a slow
  upload while the builder can fetch faster directly from the source. To use
  it, put the following snippet as a new overlay:
<programlisting>
    self: super:
      (super.prefer-remote-fetch self super)
  </programlisting>
  A full configuration example for that sets the overlay up for your own
  account, could look like this
<programlisting>
    $ mkdir ~/.config/nixpkgs/overlays/
    $ cat &gt; ~/.config/nixpkgs/overlays/prefer-remote-fetch.nix &lt;&lt;EOF
      self: super: super.prefer-remote-fetch self super
    EOF
  </programlisting>
 </para>
</section>