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Overlays: allow overlays to be specified in a file

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Michael Peyton Jones 2017-08-09 19:47:27 +01:00 committed by Nicolas B. Pierron
parent 060a41d225
commit 9235ff1259
2 changed files with 70 additions and 26 deletions
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56
doc/overlays.xml
View File

@ -17,42 +17,68 @@ if multiple layers override the same package.</para>
<section xml:id="sec-overlays-install"> <section xml:id="sec-overlays-install">
<title>Installing overlays</title> <title>Installing overlays</title>
<para>The list of overlays is determined as follows: <para>The list of overlays is determined as follows.</para>
<para>If the <varname>overlays</varname> argument is not provided explicitly, we look for overlays in a path. The path
is determined as follows:
<orderedlist> <orderedlist>
<listitem> <listitem>
<para>First, if an <varname>overlays</varname> argument to the nixpkgs function itself is given, <para>First, if an <varname>overlays</varname> argument to the nixpkgs function itself is given,
then that is used. This can be passed explicitly when importing nipxkgs, for example then that is used.</para>
<literal>import &lt;nixpkgs> { overlays = [ overlay1 overlay2 ] }</literal>.</para>
<para>On a NixOS system the value of the <literal>nixpkgs.overlays</literal> option, if present, <para>This can be passed explicitly when importing nipxkgs, for example
is passed to the system Nixpkgs in this way. Note that this does not affect the overlays for <literal>import &lt;nixpkgs> { overlays = [ overlay1 overlay2 ]; }</literal>.</para>
non-NixOS operations (e.g. <literal>nix-env</literal>), which are looked up independently.</para>
</listitem> </listitem>
<listitem> <listitem>
<para>Otherwise, if the Nix path entry <literal>&lt;nixpkgs-overlays></literal> exists and is a <para>Otherwise, if the Nix path entry <literal>&lt;nixpkgs-overlays></literal> exists, we look for overlays
directory, then the result is the set of overlays found in that directory, ordered lexicographically.</para> at that path, as described below.</para>
<para>See the section on <literal>NIX_PATH</literal> in the Nix manual for more details on how to <para>See the section on <literal>NIX_PATH</literal> in the Nix manual for more details on how to
set a value for <literal>&lt;nixpkgs-overlays>.</literal></para> set a value for <literal>&lt;nixpkgs-overlays>.</literal></para>
</listitem> </listitem>
<listitem> <listitem>
<para>Otherwise, if <filename>~/.config/nixpkgs/overlays/</filename> exists and is a directory, then <para>If one of <filename>~/.config/nixpkgs/overlays.nix</filename> and
the result is the set of overlays found in that directory, ordered lexicographically.</para> <filename>~/.config/nixpkgs/overlays/</filename> exists, then we look for overlays at that path, as
described below. It is an error if both exist.</para>
</listitem> </listitem>
</orderedlist> </orderedlist>
</para> </para>
<para>For the second and third options, overlays are extracted from the given directory as files, <para>If we are looking for overlays at a path, then there are two cases:
directories containing a <filename>default.nix</filename>, or symlinks to one of those.</para> <itemizedlist>
<listitem>
<para>If the path is a file, then the file is imported as a Nix expression and used as the list of
overlays.</para>
</listitem>
<para>The last option provides a convenient way to install an overlay from a repository, <listitem>
by cloning the overlay's repository and adding a symbolic link to it in <para>If the path is a directory, then we take the content of the directory, order it
<filename>~/.config/nixpkgs/overlays/</filename>.</para> lexicographically, and attempt to interpret each as an overlay by:
<itemizedlist>
<listitem>
<para>Importing the file, if it is a <literal>.nix</literal> file.</para>
</listitem>
<listitem>
<para>Importing a top-level <filename>default.nix</filename> file, if it is a directory.</para>
</listitem>
</itemizedlist>
</para>
</listitem>
</itemizedlist>
</para>
<para>On a NixOS system the value of the <literal>nixpkgs.overlays</literal> option, if present,
is passed to the system Nixpkgs directly as an argument. Note that this does not affect the overlays for
non-NixOS operations (e.g. <literal>nix-env</literal>), which are looked up independently.</para>
<para>The <filename>overlays.nix</filename> option therefore provides a convenient way to use the same
overlays for a NixOS system configuration and user configuration: the same file can be used
as <filename>overlays.nix</filename> and imported as the value of <literal>nixpkgs.overlays</literal>.</para>
</section> </section>

40
pkgs/top-level/impure.nix
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@ -40,18 +40,36 @@ in
# collections of packages. These collection of packages are part of the # collections of packages. These collection of packages are part of the
# fix-point made by Nixpkgs. # fix-point made by Nixpkgs.
overlays ? let overlays ? let
dirPath = try (if pathExists <nixpkgs-overlays> then <nixpkgs-overlays> else "") ""; isDir = path: pathExists (path + "/.");
dirHome = homeDir + "/.config/nixpkgs/overlays"; pathOverlays = try <nixpkgs-overlays> "";
dirCheck = dir: dir != "" && pathExists (dir + "/."); homeOverlaysFile = homeDir + "/.config/nixpkgs/overlays.nix";
overlays = dir: homeOverlaysDir = homeDir + "/.config/nixpkgs/overlays";
let content = readDir dir; in overlays = path:
map (n: import (dir + ("/" + n))) # check if the path is a directory or a file
(builtins.filter (n: builtins.match ".*\.nix" n != null || pathExists (dir + ("/" + n + "/default.nix"))) if isDir path then
(attrNames content)); # it's a directory, so the set of overlays from the directory, ordered lexicographically
let content = readDir path; in
map (n: import (path + ("/" + n)))
(builtins.filter (n: builtins.match ".*\.nix" n != null || pathExists (path + ("/" + n + "/default.nix")))
(attrNames content))
else
# it's a file, so the result is the contents of the file itself
import path;
in in
if dirPath != "" then if pathOverlays != "" && pathExists pathOverlays then overlays pathOverlays
overlays dirPath else if pathExists homeOverlaysFile && pathExists homeOverlaysDir then
else if dirCheck dirHome then overlays dirHome throw ''
Nixpkgs overlays can be specified with ${homeOverlaysFile} or ${homeOverlaysDir}, but not both.
Please remove one of them and try again.
''
else if pathExists homeOverlaysFile then
if isDir homeOverlaysFile then
throw (homeOverlaysFile + " should be a file")
else overlays homeOverlaysFile
else if pathExists homeOverlaysDir then
if !(isDir homeOverlaysDir) then
throw (homeOverlaysDir + " should be a directory")
else overlays homeOverlaysDir
else [] else []
, ... , ...