anchor.diff:          ##     don't end up in the Nix store.
           preStart = let
             sshDir = "${cfg.dataDir}/.ssh";
  +          metaData = if cfg.meta-data == ""
  +            then ""
  +            else "meta-data=${cfg.meta-data}";
           in
             ''
               mkdir -m 0700 -p "${sshDir}"
  
positive.code:             cat > "${cfg.dataDir}/buildkite-agent.cfg" <<EOF
              token="$(cat ${toString cfg.tokenPath})"
              name="${cfg.name}"
              meta-data="${cfg.meta-data}"
              build-path="${cfg.dataDir}/builds"
              hooks-path="${cfg.hooksPath}"
              ${cfg.extraConfig}
  
negative.code:           '';
  
          serviceConfig =
            { ExecStart = "${cfg.buildkite-agent}/bin/buildkite-agent start --config /var/lib/buildkite-agent/buildkite-agent.cfg";
              User = "buildkite-agent";
              RestartSec = 5;
              Restart = "on-failure";
  