nixos: add module for tempo

It's very barebones but should be OK for now.

1 files changed, 68 insertions, 0 deletions

diff --git a/nixos/modules/services/tracing/tempo.nix b/nixos/modules/services/tracing/tempo.nix
new file mode 100644
index 000000000000..15491a51c8e9
--- /dev/null
+++ b/nixos/modules/services/tracing/tempo.nix
@@ -0,0 +1,68 @@
+{ config, lib, pkgs, ... }:
+
+let
+  inherit (lib) mkEnableOption mkIf mkOption types;
+
+  cfg = config.services.tempo;
+
+  settingsFormat = pkgs.formats.yaml {};
+in {
+  options.services.tempo = {
+    enable = mkEnableOption "Grafana Tempo";
+
+    settings = mkOption {
+      type = settingsFormat.type;
+      default = {};
+      description = ''
+        Specify the configuration for Tempo in Nix.
+
+        See https://grafana.com/docs/tempo/latest/configuration/ for available options.
+      '';
+    };
+
+    configFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        Specify a path to a configuration file that Tempo should use.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # for tempo-cli and friends
+    environment.systemPackages = [ pkgs.tempo ];
+
+    assertions = [{
+      assertion = (
+        (cfg.settings == {}) != (cfg.configFile == null)
+      );
+      message  = ''
+        Please specify a configuration for Tempo with either
+        'services.tempo.settings' or
+        'services.tempo.configFile'.
+      '';
+    }];
+
+    systemd.services.tempo = {
+      description = "Grafana Tempo Service Daemon";
+      wantedBy = [ "multi-user.target" ];
+
+      serviceConfig = let
+        conf = if cfg.configFile == null
+               then settingsFormat.generate "config.yaml" cfg.settings
+               else cfg.configFile;
+      in
+      {
+        ExecStart = "${pkgs.tempo}/bin/tempo --config.file=${conf}";
+        DynamicUser = true;
+        Restart = "always";
+        ProtectSystem = "full";
+        DevicePolicy = "closed";
+        NoNewPrivileges = true;
+        WorkingDirectory = "/var/lib/tempo";
+        StateDirectory = "tempo";
+      };
+    };
+  };
+}