nixpkgs/nixos/modules/services/logging/promtail.nix
Zhaofeng Li b6ad701a2c nixos/promtail: Allow write access to positions file if not in CacheDirectory
Because of `ProtectSystem=strict`, Promtail cannot write to the positions
file if it's not in its `CacheDirectory` (the default value).
2021-08-25 22:54:39 -07:00

92 lines
2.7 KiB
Nix

{ config, lib, pkgs, ... }: with lib;
let
cfg = config.services.promtail;
prettyJSON = conf: pkgs.runCommandLocal "promtail-config.json" {} ''
echo '${builtins.toJSON conf}' | ${pkgs.buildPackages.jq}/bin/jq 'del(._module)' > $out
'';
allowSystemdJournal = cfg.configuration ? scrape_configs && lib.any (v: v ? journal) cfg.configuration.scrape_configs;
allowPositionsFile = !lib.hasPrefix "/var/cache/promtail" positionsFile;
positionsFile = cfg.configuration.positions.filename;
in {
options.services.promtail = with types; {
enable = mkEnableOption "the Promtail ingresser";
configuration = mkOption {
type = (pkgs.formats.json {}).type;
description = ''
Specify the configuration for Promtail in Nix.
'';
};
extraFlags = mkOption {
type = listOf str;
default = [];
example = [ "--server.http-listen-port=3101" ];
description = ''
Specify a list of additional command line flags,
which get escaped and are then passed to Loki.
'';
};
};
config = mkIf cfg.enable {
services.promtail.configuration.positions.filename = mkDefault "/var/cache/promtail/positions.yaml";
systemd.services.promtail = {
description = "Promtail log ingress";
wantedBy = [ "multi-user.target" ];
stopIfChanged = false;
serviceConfig = {
Restart = "on-failure";
TimeoutStopSec = 10;
ExecStart = "${pkgs.grafana-loki}/bin/promtail -config.file=${prettyJSON cfg.configuration} ${escapeShellArgs cfg.extraFlags}";
ProtectSystem = "strict";
ProtectHome = true;
PrivateTmp = true;
PrivateDevices = true;
ProtectKernelTunables = true;
ProtectControlGroups = true;
RestrictSUIDSGID = true;
PrivateMounts = true;
CacheDirectory = "promtail";
ReadWritePaths = lib.optional allowPositionsFile (builtins.dirOf positionsFile);
User = "promtail";
Group = "promtail";
CapabilityBoundingSet = "";
NoNewPrivileges = true;
ProtectKernelModules = true;
SystemCallArchitectures = "native";
ProtectKernelLogs = true;
ProtectClock = true;
LockPersonality = true;
ProtectHostname = true;
RestrictRealtime = true;
MemoryDenyWriteExecute = true;
PrivateUsers = true;
SupplementaryGroups = lib.optional (allowSystemdJournal) "systemd-journal";
} // (optionalAttrs (!pkgs.stdenv.isAarch64) { # FIXME: figure out why this breaks on aarch64
SystemCallFilter = "@system-service";
});
};
users.groups.promtail = {};
users.users.promtail = {
description = "Promtail service user";
isSystemUser = true;
group = "promtail";
};
};
}