nixpkgs/nixos/modules/config/system-environment.nix
Jörg Thalheim 1645acf1d3 nixos: reduce pam files rebuilds on updates
Before whenever environment variables changed, pam files had to be
rebuild.

This is expensive since each file needs its own sandbox set up.
2021-08-20 23:43:30 +02:00

105 lines
3.4 KiB
Nix

# This module defines a system-wide environment that will be
# initialised by pam_env (that is, not only in shells).
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.environment;
in
{
options = {
environment.sessionVariables = mkOption {
default = {};
description = ''
A set of environment variables used in the global environment.
These variables will be set by PAM early in the login process.
The value of each session variable can be either a string or a
list of strings. The latter is concatenated, interspersed with
colon characters.
Note, due to limitations in the PAM format values may not
contain the <literal>"</literal> character.
Also, these variables are merged into
<xref linkend="opt-environment.variables"/> and it is
therefore not possible to use PAM style variables such as
<code>@{HOME}</code>.
'';
type = with types; attrsOf (either str (listOf str));
apply = mapAttrs (n: v: if isList v then concatStringsSep ":" v else v);
};
environment.profileRelativeSessionVariables = mkOption {
type = types.attrsOf (types.listOf types.str);
example = { PATH = [ "/bin" ]; MANPATH = [ "/man" "/share/man" ]; };
description = ''
Attribute set of environment variable used in the global
environment. These variables will be set by PAM early in the
login process.
Variable substitution is available as described in
<citerefentry>
<refentrytitle>pam_env.conf</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>.
Each attribute maps to a list of relative paths. Each relative
path is appended to the each profile of
<option>environment.profiles</option> to form the content of
the corresponding environment variable.
Also, these variables are merged into
<xref linkend="opt-environment.profileRelativeEnvVars"/> and it is
therefore not possible to use PAM style variables such as
<code>@{HOME}</code>.
'';
};
};
config = {
environment.etc."pam/environment".text = let
suffixedVariables =
flip mapAttrs cfg.profileRelativeSessionVariables (envVar: suffixes:
flip concatMap cfg.profiles (profile:
map (suffix: "${profile}${suffix}") suffixes
)
);
# We're trying to use the same syntax for PAM variables and env variables.
# That means we need to map the env variables that people might use to their
# equivalent PAM variable.
replaceEnvVars = replaceStrings ["$HOME" "$USER"] ["@{HOME}" "@{PAM_USER}"];
pamVariable = n: v:
''${n} DEFAULT="${concatStringsSep ":" (map replaceEnvVars (toList v))}"'';
pamVariables =
concatStringsSep "\n"
(mapAttrsToList pamVariable
(zipAttrsWith (n: concatLists)
[
# Make sure security wrappers are prioritized without polluting
# shell environments with an extra entry. Sessions which depend on
# pam for its environment will otherwise have eg. broken sudo. In
# particular Gnome Shell sometimes fails to source a proper
# environment from a shell.
{ PATH = [ config.security.wrapperDir ]; }
(mapAttrs (n: toList) cfg.sessionVariables)
suffixedVariables
]));
in ''
${pamVariables}
'';
};
}