1 files changed, 87 insertions, 0 deletions
diff --git a/nixos/modules/services/logging/promtail.nix b/nixos/modules/services/logging/promtail.nix
new file mode 100644
index 00000000000..34211687dc1
--- /dev/null
+++ b/nixos/modules/services/logging/promtail.nix
@@ -0,0 +1,87 @@
+{ 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)' > $out
+  '';
+
+  allowSystemdJournal = cfg.configuration ? scrape_configs && lib.any (v: v ? journal) cfg.configuration.scrape_configs;
+in {
+  options.services.promtail = with types; {
+    enable = mkEnableOption "the Promtail ingresser";
+
+
+    configuration = mkOption {
+      type = (pkgs.formats.json {}).type;
+      description = ''
+        Specify the configuration for Promtail in Nix.
+      '';
+    };
+
+    extraFlags = mkOption {
+      type = listOf str;
+      default = [];
+      example = [ "--server.http-listen-port=3101" ];
+      description = ''
+        Specify a list of additional command line flags,
+        which get escaped and are then passed to Loki.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    services.promtail.configuration.positions.filename = mkDefault "/var/cache/promtail/positions.yaml";
+
+    systemd.services.promtail = {
+      description = "Promtail log ingress";
+      wantedBy = [ "multi-user.target" ];
+      stopIfChanged = false;
+
+      serviceConfig = {
+        Restart = "on-failure";
+        TimeoutStopSec = 10;
+
+        ExecStart = "${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";
+
+        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";
+    };
+  };
+}