pkgs.krops: add rebuild

pkgs/krops/default.nix

@@ -2,7 +2,19 @@ let
   lib = import ../../lib;
 in
 
-{ nix, openssh, populate, writeDash, writeJSON }: {
+{ exec, nix, openssh, populate, writeDash, writeJSON }: rec {
+
+  rebuild = target:
+    exec "rebuild.${target.host}" rec {
+      filename = "${openssh}/bin/ssh";
+      argv = [
+        filename
+        "-l" target.user
+        "-p" target.port
+        target.host
+        "nixos-rebuild switch -I ${lib.escapeShellArg target.path}"
+      ];
+    };
 
   writeDeploy = name: { source, target }: let
     target' = lib.mkTarget target;
@@ -10,9 +22,7 @@ in
     writeDash name ''
       set -efu
       ${populate { inherit source; target = target'; }}
-      ${openssh}/bin/ssh \
-          ${target'.user}@${target'.host} -p ${target'.port} \
-          nixos-rebuild switch -I ${target'.path}
+      ${rebuild target'}
     '';
 
   writeTest = name: { source, target }: let