Merge pull request #322035 from jpds/nixos-nats-validate-config

nixos/nats: Implemented configuration verification

nixos/modules/services/networking/nats.nix

···
 
   configFile = format.generate "nats.conf" cfg.settings;
 
+  validateConfig = file:
+  pkgs.runCommand "validate-nats-conf" {
+    nativeBuildInputs = [ pkgs.nats-server ];
+  } ''
+    nats-server --config "${configFile}" -t
+    ln -s "${configFile}" "$out"
+  '';
 in {
 
   ### Interface
···
         })
         {
           Type = "simple";
-          ExecStart = "${pkgs.nats-server}/bin/nats-server -c ${configFile}";
+          ExecStart = "${pkgs.nats-server}/bin/nats-server -c ${validateConfig configFile}";
           ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
           ExecStop = "${pkgs.coreutils}/bin/kill -SIGINT $MAINPID";
           Restart = "on-failure";