nixpkgs/nixos/modules/programs/rust-motd.nix
Maximilian Bosch 57de6a8550
nixos/rust-motd: refactor assertion and TOML generation
* `sort (<)` also works for strings (TIL!), so no need for comparing
  length and whether all keys from `cfg.settings` exist in `cfg.order`
  (slightly less overhead).

* Don't build another piece of JSON (`orderedSections`), simply use
  `cfg.settings`/`cfg.order` with `__structuredAttrs` to ensure a
  properly ordered TOML.

  This also has the upside of not having to do quote hackery.

* Also, a freeform submodule isn't strictly needed because we don't have
  any special options defined, so replacing that with
  `attrsOf format.type`.

Co-authored-by: Silvan Mosberger <github@infinisil.com>
2023-09-29 11:13:27 +02:00

150 lines
4.6 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.programs.rust-motd;
format = pkgs.formats.toml { };
# Order the sections in the TOML according to the order of sections
# in `cfg.order`.
motdConf = pkgs.runCommand "motd.conf"
{
__structuredAttrs = true;
inherit (cfg) order settings;
nativeBuildInputs = [ pkgs.remarshal pkgs.jq ];
}
''
cat "$NIX_ATTRS_JSON_FILE" \
| jq '.settings as $settings
| .order
| map({ key: ., value: $settings."\(.)" })
| from_entries' -r \
| json2toml /dev/stdin "$out"
'';
in {
options.programs.rust-motd = {
enable = mkEnableOption (lib.mdDoc "rust-motd");
enableMotdInSSHD = mkOption {
default = true;
type = types.bool;
description = mdDoc ''
Whether to let `openssh` print the
result when entering a new `ssh`-session.
By default either nothing or a static file defined via
[](#opt-users.motd) is printed. Because of that,
the latter option is incompatible with this module.
'';
};
refreshInterval = mkOption {
default = "*:0/5";
type = types.str;
description = mdDoc ''
Interval in which the {manpage}`motd(5)` file is refreshed.
For possible formats, please refer to {manpage}`systemd.time(7)`.
'';
};
order = mkOption {
type = types.listOf types.str;
default = attrNames cfg.settings;
defaultText = literalExpression "attrNames cfg.settings";
description = mdDoc ''
The order of the sections in [](#opt-programs.rust-motd.settings).
By default they are ordered alphabetically.
Context: since attribute sets in Nix are always
ordered alphabetically internally this means that
```nix
{
uptime = { /* ... */ };
banner = { /* ... */ };
}
```
will still have `banner` displayed before `uptime`.
To work around that, this option can be used to define the order of all keys,
i.e.
```nix
{
order = [
"uptime"
"banner"
];
}
```
makes sure that `uptime` is placed before `banner` in the motd.
'';
};
settings = mkOption {
type = types.attrsOf format.type;
description = mdDoc ''
Settings on what to generate. Please read the
[upstream documentation](https://github.com/rust-motd/rust-motd/blob/main/README.md#configuration)
for further information.
'';
};
};
config = mkIf cfg.enable {
assertions = [
{ assertion = config.users.motd == null;
message = ''
`programs.rust-motd` is incompatible with `users.motd`!
'';
}
{ assertion = sort (a: b: a < b) cfg.order == attrNames cfg.settings;
message = ''
Please ensure that every section from `programs.rust-motd.settings` is present in
`programs.rust-motd.order`.
'';
}
];
systemd.services.rust-motd = {
path = with pkgs; [ bash ];
documentation = [ "https://github.com/rust-motd/rust-motd/blob/v${pkgs.rust-motd.version}/README.md" ];
description = "motd generator";
wantedBy = [ "multi-user.target" ];
serviceConfig = {
ExecStart = "${pkgs.writeShellScript "update-motd" ''
${pkgs.rust-motd}/bin/rust-motd ${motdConf} > motd
''}";
CapabilityBoundingSet = [ "" ];
LockPersonality = true;
MemoryDenyWriteExecute = true;
NoNewPrivileges = true;
PrivateDevices = true;
PrivateTmp = true;
ProtectClock = true;
ProtectControlGroups = true;
ProtectHome = true;
ProtectHostname = true;
ProtectKernelModules = true;
ProtectKernelLogs = true;
ProtectKernelTunables = true;
ProtectSystem = "full";
StateDirectory = "rust-motd";
RestrictAddressFamilies = [ "AF_UNIX" ];
RestrictNamespaces = true;
RestrictRealtime = true;
RestrictSUIDSGID = true;
RemoveIPC = true;
WorkingDirectory = "/var/lib/rust-motd";
};
};
systemd.timers.rust-motd = {
wantedBy = [ "timers.target" ];
timerConfig.OnCalendar = cfg.refreshInterval;
};
security.pam.services.sshd.text = mkIf cfg.enableMotdInSSHD (mkDefault (mkAfter ''
session optional ${pkgs.pam}/lib/security/pam_motd.so motd=/var/lib/rust-motd/motd
''));
services.openssh.extraConfig = mkIf (cfg.settings ? last_login && cfg.settings.last_login != {}) ''
PrintLastLog no
'';
};
meta.maintainers = with maintainers; [ ma27 ];
}