diff options
| -rw-r--r-- | doc/overlays.xml | 56 | ||||
| -rw-r--r-- | pkgs/top-level/impure.nix | 40 |
2 files changed, 70 insertions, 26 deletions
diff --git a/doc/overlays.xml b/doc/overlays.xml index ad31b90299e7..cc0aef447d2d 100644 --- a/doc/overlays.xml +++ b/doc/overlays.xml @@ -17,42 +17,68 @@ if multiple layers override the same package.</para> <section xml:id="sec-overlays-install"> <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> <listitem> <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 - <literal>import <nixpkgs> { overlays = [ overlay1 overlay2 ] }</literal>.</para> + then that is used.</para> - <para>On a NixOS system the value of the <literal>nixpkgs.overlays</literal> option, if present, - is passed to the system Nixpkgs in this way. 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>This can be passed explicitly when importing nipxkgs, for example + <literal>import <nixpkgs> { overlays = [ overlay1 overlay2 ]; }</literal>.</para> </listitem> <listitem> - <para>Otherwise, if the Nix path entry <literal><nixpkgs-overlays></literal> exists and is a - directory, then the result is the set of overlays found in that directory, ordered lexicographically.</para> + <para>Otherwise, if the Nix path entry <literal><nixpkgs-overlays></literal> exists, we look for overlays + 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 set a value for <literal><nixpkgs-overlays>.</literal></para> </listitem> <listitem> - <para>Otherwise, if <filename>~/.config/nixpkgs/overlays/</filename> exists and is a directory, then - the result is the set of overlays found in that directory, ordered lexicographically.</para> + <para>If one of <filename>~/.config/nixpkgs/overlays.nix</filename> and + <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> </orderedlist> </para> -<para>For the second and third options, overlays are extracted from the given directory as files, -directories containing a <filename>default.nix</filename>, or symlinks to one of those.</para> +<para>If we are looking for overlays at a path, then there are two cases: +<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> + + <listitem> + <para>If the path is a directory, then we take the content of the directory, order it + 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 last option provides a convenient way to install an overlay from a repository, -by cloning the overlay's repository and adding a symbolic link to it in -<filename>~/.config/nixpkgs/overlays/</filename>.</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> diff --git a/pkgs/top-level/impure.nix b/pkgs/top-level/impure.nix index c0cf8fb09113..a4d313a1b991 100644 --- a/pkgs/top-level/impure.nix +++ b/pkgs/top-level/impure.nix @@ -40,18 +40,36 @@ in # collections of packages. These collection of packages are part of the # fix-point made by Nixpkgs. overlays ? let - dirPath = try (if pathExists <nixpkgs-overlays> then <nixpkgs-overlays> else "") ""; - dirHome = homeDir + "/.config/nixpkgs/overlays"; - dirCheck = dir: dir != "" && pathExists (dir + "/."); - overlays = dir: - let content = readDir dir; in - map (n: import (dir + ("/" + n))) - (builtins.filter (n: builtins.match ".*\.nix" n != null || pathExists (dir + ("/" + n + "/default.nix"))) - (attrNames content)); + isDir = path: pathExists (path + "/."); + pathOverlays = try <nixpkgs-overlays> ""; + homeOverlaysFile = homeDir + "/.config/nixpkgs/overlays.nix"; + homeOverlaysDir = homeDir + "/.config/nixpkgs/overlays"; + overlays = path: + # check if the path is a directory or a file + if isDir path then + # 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 - if dirPath != "" then - overlays dirPath - else if dirCheck dirHome then overlays dirHome + if pathOverlays != "" && pathExists pathOverlays then overlays pathOverlays + else if pathExists homeOverlaysFile && pathExists homeOverlaysDir then + 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 [] , ... |