1 files changed, 31 insertions, 11 deletions

diff --git a/nixos/modules/services/monitoring/telegraf.nix b/nixos/modules/services/monitoring/telegraf.nix
index 5d131557e8be..1fc17ec72daf 100644
--- a/nixos/modules/services/monitoring/telegraf.nix
+++ b/nixos/modules/services/monitoring/telegraf.nix
@@ -5,14 +5,8 @@ with lib;
 let
   cfg = config.services.telegraf;
 
-  configFile = pkgs.runCommand "config.toml" {
-    buildInputs = [ pkgs.remarshal ];
-    preferLocalBuild = true;
-  } ''
-    remarshal -if json -of toml \
-      < ${pkgs.writeText "config.json" (builtins.toJSON cfg.extraConfig)} \
-      > $out
-  '';
+  settingsFormat = pkgs.formats.toml {};
+  configFile = settingsFormat.generate "config.toml" cfg.extraConfig;
 in {
   ###### interface
   options = {
@@ -26,10 +20,23 @@ in {
         type = types.package;
       };
 
+      environmentFiles = mkOption {
+        type = types.nullOr (types.listOf types.path);
+        default = [];
+        example = "/run/keys/telegraf.env";
+        description = ''
+          File to load as environment file. Environment variables
+          from this file will be interpolated into the config file
+          using envsubst with this syntax:
+          <literal>$ENVIRONMENT ''${VARIABLE}</literal>
+          This is useful to avoid putting secrets into the nix store.
+        '';
+      };
+
       extraConfig = mkOption {
         default = {};
         description = "Extra configuration options for telegraf";
-        type = types.attrs;
+        type = settingsFormat.type;
         example = {
           outputs = {
             influxdb = {
@@ -51,15 +58,28 @@ in {
 
   ###### implementation
   config = mkIf config.services.telegraf.enable {
-    systemd.services.telegraf = {
+    systemd.services.telegraf = let
+      finalConfigFile = if config.services.telegraf.environmentFiles == []
+                        then configFile
+                        else "/var/run/telegraf/config.toml";
+    in {
       description = "Telegraf Agent";
       wantedBy = [ "multi-user.target" ];
       after = [ "network-online.target" ];
       serviceConfig = {
-        ExecStart=''${cfg.package}/bin/telegraf -config "${configFile}"'';
+        EnvironmentFile = config.services.telegraf.environmentFiles;
+        ExecStartPre = lib.optional (config.services.telegraf.environmentFiles != [])
+          (pkgs.writeShellScript "pre-start" ''
+            umask 077
+            ${pkgs.envsubst}/bin/envsubst -i "${configFile}" > /var/run/telegraf/config.toml
+          '');
+        ExecStart=''${cfg.package}/bin/telegraf -config ${finalConfigFile}'';
         ExecReload="${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+        RuntimeDirectory = "telegraf";
         User = "telegraf";
         Restart = "on-failure";
+        # for ping probes
+        AmbientCapabilities = [ "CAP_NET_RAW" ];
       };
     };