nixpkgs/nixos/lib/systemd-lib.nix

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{ config, lib, pkgs }:
with lib;
let
cfg = config.systemd;
lndir = "${pkgs.buildPackages.xorg.lndir}/bin/lndir";
systemd = cfg.package;
in rec {
shellEscape = s: (replaceChars [ "\\" ] [ "\\\\" ] s);
mkPathSafeName = lib.replaceChars ["@" ":" "\\" "[" "]"] ["-" "-" "-" "" ""];
# a type for options that take a unit name
unitNameType = types.strMatching "[a-zA-Z0-9@%:_.\\-]+[.](service|socket|device|mount|automount|swap|target|path|timer|scope|slice)";
makeUnit = name: unit:
if unit.enable then
pkgs.runCommand "unit-${mkPathSafeName name}"
{ preferLocalBuild = true;
allowSubstitutes = false;
inherit (unit) text;
}
''
mkdir -p $out
echo -n "$text" > $out/${shellEscape name}
''
else
pkgs.runCommand "unit-${mkPathSafeName name}-disabled"
{ preferLocalBuild = true;
allowSubstitutes = false;
}
''
mkdir -p $out
ln -s /dev/null $out/${shellEscape name}
'';
boolValues = [true false "yes" "no"];
digits = map toString (range 0 9);
isByteFormat = s:
let
l = reverseList (stringToCharacters s);
suffix = head l;
nums = tail l;
in elem suffix (["K" "M" "G" "T"] ++ digits)
&& all (num: elem num digits) nums;
assertByteFormat = name: group: attr:
optional (attr ? ${name} && ! isByteFormat attr.${name})
"Systemd ${group} field `${name}' must be in byte format [0-9]+[KMGT].";
hexChars = stringToCharacters "0123456789abcdefABCDEF";
isMacAddress = s: stringLength s == 17
&& flip all (splitString ":" s) (bytes:
all (byte: elem byte hexChars) (stringToCharacters bytes)
);
assertMacAddress = name: group: attr:
optional (attr ? ${name} && ! isMacAddress attr.${name})
"Systemd ${group} field `${name}' must be a valid mac address.";
isPort = i: i >= 0 && i <= 65535;
assertPort = name: group: attr:
optional (attr ? ${name} && ! isPort attr.${name})
"Error on the systemd ${group} field `${name}': ${attr.name} is not a valid port number.";
assertValueOneOf = name: values: group: attr:
optional (attr ? ${name} && !elem attr.${name} values)
"Systemd ${group} field `${name}' cannot have value `${toString attr.${name}}'.";
assertHasField = name: group: attr:
optional (!(attr ? ${name}))
"Systemd ${group} field `${name}' must exist.";
assertRange = name: min: max: group: attr:
optional (attr ? ${name} && !(min <= attr.${name} && max >= attr.${name}))
"Systemd ${group} field `${name}' is outside the range [${toString min},${toString max}]";
assertMinimum = name: min: group: attr:
optional (attr ? ${name} && attr.${name} < min)
"Systemd ${group} field `${name}' must be greater than or equal to ${toString min}";
assertOnlyFields = fields: group: attr:
let badFields = filter (name: ! elem name fields) (attrNames attr); in
optional (badFields != [ ])
"Systemd ${group} has extra fields [${concatStringsSep " " badFields}].";
assertInt = name: group: attr:
optional (attr ? ${name} && !isInt attr.${name})
"Systemd ${group} field `${name}' is not an integer";
checkUnitConfig = group: checks: attrs: let
# We're applied at the top-level type (attrsOf unitOption), so the actual
# unit options might contain attributes from mkOverride and mkIf that we need to
# convert into single values before checking them.
defs = mapAttrs (const (v:
if v._type or "" == "override" then v.content
else if v._type or "" == "if" then v.content
else v
)) attrs;
errors = concatMap (c: c group defs) checks;
in if errors == [] then true
else builtins.trace (concatStringsSep "\n" errors) false;
toOption = x:
if x == true then "true"
else if x == false then "false"
else toString x;
attrsToSection = as:
concatStrings (concatLists (mapAttrsToList (name: value:
map (x: ''
${name}=${toOption x}
'')
(if isList value then value else [value]))
as));
generateUnits = { allowCollisions ? true, type, units, upstreamUnits, upstreamWants, packages ? cfg.packages, package ? cfg.package }:
let
typeDir = ({
system = "system";
initrd = "system";
user = "user";
nspawn = "nspawn";
}).${type};
in pkgs.runCommand "${type}-units"
{ preferLocalBuild = true;
allowSubstitutes = false;
} ''
mkdir -p $out
# Copy the upstream systemd units we're interested in.
for i in ${toString upstreamUnits}; do
fn=${package}/example/systemd/${typeDir}/$i
if ! [ -e $fn ]; then echo "missing $fn"; false; fi
if [ -L $fn ]; then
target="$(readlink "$fn")"
if [ ''${target:0:3} = ../ ]; then
ln -s "$(readlink -f "$fn")" $out/
else
cp -pd $fn $out/
fi
else
ln -s $fn $out/
fi
done
# Copy .wants links, but only those that point to units that
# we're interested in.
for i in ${toString upstreamWants}; do
fn=${package}/example/systemd/${typeDir}/$i
if ! [ -e $fn ]; then echo "missing $fn"; false; fi
x=$out/$(basename $fn)
mkdir $x
for i in $fn/*; do
y=$x/$(basename $i)
cp -pd $i $y
if ! [ -e $y ]; then rm $y; fi
done
done
# Symlink all units provided listed in systemd.packages.
packages="${toString packages}"
# Filter duplicate directories
declare -A unique_packages
for k in $packages ; do unique_packages[$k]=1 ; done
for i in ''${!unique_packages[@]}; do
for fn in $i/etc/systemd/${typeDir}/* $i/lib/systemd/${typeDir}/*; do
if ! [[ "$fn" =~ .wants$ ]]; then
if [[ -d "$fn" ]]; then
targetDir="$out/$(basename "$fn")"
mkdir -p "$targetDir"
${lndir} "$fn" "$targetDir"
else
ln -s $fn $out/
fi
fi
done
done
# Symlink all units defined by systemd.units. If these are also
# provided by systemd or systemd.packages, then add them as
# <unit-name>.d/overrides.conf, which makes them extend the
# upstream unit.
for i in ${toString (mapAttrsToList (n: v: v.unit) units)}; do
fn=$(basename $i/*)
if [ -e $out/$fn ]; then
if [ "$(readlink -f $i/$fn)" = /dev/null ]; then
ln -sfn /dev/null $out/$fn
else
${if allowCollisions then ''
mkdir -p $out/$fn.d
ln -s $i/$fn $out/$fn.d/overrides.conf
'' else ''
echo "Found multiple derivations configuring $fn!"
exit 1
''}
fi
else
ln -fs $i/$fn $out/
fi
done
# Create service aliases from aliases option.
${concatStrings (mapAttrsToList (name: unit:
concatMapStrings (name2: ''
ln -sfn '${name}' $out/'${name2}'
'') unit.aliases) units)}
# Create .wants and .requires symlinks from the wantedBy and
# requiredBy options.
${concatStrings (mapAttrsToList (name: unit:
concatMapStrings (name2: ''
mkdir -p $out/'${name2}.wants'
ln -sfn '../${name}' $out/'${name2}.wants'/
'') unit.wantedBy) units)}
${concatStrings (mapAttrsToList (name: unit:
concatMapStrings (name2: ''
mkdir -p $out/'${name2}.requires'
ln -sfn '../${name}' $out/'${name2}.requires'/
'') unit.requiredBy) units)}
${optionalString (type == "system") ''
# Stupid misc. symlinks.
ln -s ${cfg.defaultUnit} $out/default.target
ln -s ${cfg.ctrlAltDelUnit} $out/ctrl-alt-del.target
ln -s rescue.target $out/kbrequest.target
mkdir -p $out/getty.target.wants/
ln -s ../autovt@tty1.service $out/getty.target.wants/
ln -s ../remote-fs.target $out/multi-user.target.wants/
''}
''; # */
makeJobScript = name: text:
let
scriptName = replaceChars [ "\\" "@" ] [ "-" "_" ] (shellEscape name);
out = (pkgs.writeShellScriptBin scriptName ''
set -e
${text}
'').overrideAttrs (_: {
# The derivation name is different from the script file name
# to keep the script file name short to avoid cluttering logs.
name = "unit-script-${scriptName}";
});
in "${out}/bin/${scriptName}";
unitConfig = { config, options, ... }: {
config = {
unitConfig =
optionalAttrs (config.requires != [])
{ Requires = toString config.requires; }
// optionalAttrs (config.wants != [])
{ Wants = toString config.wants; }
// optionalAttrs (config.after != [])
{ After = toString config.after; }
// optionalAttrs (config.before != [])
{ Before = toString config.before; }
// optionalAttrs (config.bindsTo != [])
{ BindsTo = toString config.bindsTo; }
// optionalAttrs (config.partOf != [])
{ PartOf = toString config.partOf; }
// optionalAttrs (config.conflicts != [])
{ Conflicts = toString config.conflicts; }
// optionalAttrs (config.requisite != [])
{ Requisite = toString config.requisite; }
// optionalAttrs (config.restartTriggers != [])
{ X-Restart-Triggers = toString config.restartTriggers; }
// optionalAttrs (config.reloadTriggers != [])
{ X-Reload-Triggers = toString config.reloadTriggers; }
// optionalAttrs (config.description != "") {
Description = config.description; }
// optionalAttrs (config.documentation != []) {
Documentation = toString config.documentation; }
// optionalAttrs (config.onFailure != []) {
OnFailure = toString config.onFailure; }
// optionalAttrs (options.startLimitIntervalSec.isDefined) {
StartLimitIntervalSec = toString config.startLimitIntervalSec;
} // optionalAttrs (options.startLimitBurst.isDefined) {
StartLimitBurst = toString config.startLimitBurst;
};
};
};
mkServiceConfig = path: { name, config, ... }: {
config = mkMerge
[ {
path = mkAfter path;
environment.PATH = mkIf (config.path != []) "${makeBinPath config.path}:${makeSearchPathOutput "bin" "sbin" config.path}";
}
(mkIf (config.preStart != "")
{ serviceConfig.ExecStartPre =
[ (makeJobScript "${name}-pre-start" config.preStart) ];
})
(mkIf (config.script != "")
{ serviceConfig.ExecStart =
makeJobScript "${name}-start" config.script + " " + config.scriptArgs;
})
(mkIf (config.postStart != "")
{ serviceConfig.ExecStartPost =
[ (makeJobScript "${name}-post-start" config.postStart) ];
})
(mkIf (config.reload != "")
{ serviceConfig.ExecReload =
makeJobScript "${name}-reload" config.reload;
})
(mkIf (config.preStop != "")
{ serviceConfig.ExecStop =
makeJobScript "${name}-pre-stop" config.preStop;
})
(mkIf (config.postStop != "")
{ serviceConfig.ExecStopPost =
makeJobScript "${name}-post-stop" config.postStop;
})
];
};
# Default path for systemd services. Should be quite minimal.
serviceConfig = mkServiceConfig [
pkgs.coreutils
pkgs.findutils
pkgs.gnugrep
pkgs.gnused
systemd
];
initrdServiceConfig = mkServiceConfig [];
mountConfig = { config, ... }: {
config = {
mountConfig =
{ What = config.what;
Where = config.where;
} // optionalAttrs (config.type != "") {
Type = config.type;
} // optionalAttrs (config.options != "") {
Options = config.options;
};
};
};
automountConfig = { config, ... }: {
config = {
automountConfig =
{ Where = config.where;
};
};
};
commonUnitText = def: ''
[Unit]
${attrsToSection def.unitConfig}
'';
targetToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text =
''
[Unit]
${attrsToSection def.unitConfig}
'';
};
serviceToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Service]
${let env = cfg.globalEnvironment // def.environment;
in concatMapStrings (n:
let s = optionalString (env.${n} != null)
"Environment=${builtins.toJSON "${n}=${env.${n}}"}\n";
# systemd max line length is now 1MiB
# https://github.com/systemd/systemd/commit/e6dde451a51dc5aaa7f4d98d39b8fe735f73d2af
in if stringLength s >= 1048576 then throw "The value of the environment variable ${n} in systemd service ${name}.service is too long." else s) (attrNames env)}
${if def.reloadIfChanged then ''
X-ReloadIfChanged=true
'' else if !def.restartIfChanged then ''
X-RestartIfChanged=false
'' else ""}
${optionalString (!def.stopIfChanged) "X-StopIfChanged=false"}
${attrsToSection def.serviceConfig}
'';
};
socketToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Socket]
${attrsToSection def.socketConfig}
${concatStringsSep "\n" (map (s: "ListenStream=${s}") def.listenStreams)}
${concatStringsSep "\n" (map (s: "ListenDatagram=${s}") def.listenDatagrams)}
'';
};
timerToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Timer]
${attrsToSection def.timerConfig}
'';
};
pathToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Path]
${attrsToSection def.pathConfig}
'';
};
mountToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Mount]
${attrsToSection def.mountConfig}
'';
};
automountToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Automount]
${attrsToSection def.automountConfig}
'';
};
sliceToUnit = name: def:
{ inherit (def) aliases wantedBy requiredBy enable;
text = commonUnitText def +
''
[Slice]
${attrsToSection def.sliceConfig}
'';
};
}