target: use default port from SSH config

This is the expected behavior.
The SSH config is also implicitly used for other SSH-related settings.

lib/default.nix

@@ -57,9 +57,9 @@ let {
       elemAt' = xs: i: if lib.length xs > i then lib.elemAt xs i else null;
       filterNull = lib.filterAttrs (n: v: v != null);
     in {
-      user = lib.getEnv "LOGNAME";
+      user = lib.maybeEnv "LOGNAME" null;
       host = lib.maybeEnv "HOSTNAME" (lib.maybeHostName "localhost");
-      port = "22";
+      port = null;
       path = "/var/src";
       sudo = false;
       extraOptions = [];
@@ -70,6 +70,10 @@ let {
       path = elemAt' parse 6;
     } else s);
 
+    mkUserPortSSHOpts = target:
+      (lib.optionals (target.user != null) ["-l" target.user]) ++
+      (lib.optionals (target.port != null) ["-p" target.port]);
+
     shell = let
       isSafeChar = lib.testString "[-+./0-9:=A-Z_a-z]";
       quoteChar = c:

pkgs/krops/default.nix

@@ -20,8 +20,7 @@ in
       else
         writers.writeDash "krops.${target.host}.${lib.firstWord command}" ''
           exec ${openssh}/bin/ssh ${lib.escapeShellArgs (lib.flatten [
-            (lib.optionals (target.user != "") ["-l" target.user])
-            "-p" target.port
+            (lib.mkUserPortSSHOpts target)
             (if allocateTTY then "-t" else "-T")
             target.extraOptions
             target.host

pkgs/populate/default.nix

@@ -224,8 +224,7 @@ let
 
   ssh' = target: concatMapStringsSep " " quote (flatten [
     "${openssh}/bin/ssh"
-    (optionals (target.user != "") ["-l" target.user])
-    "-p" target.port
+    (mkUserPortSSHOpts target)
     "-T"
     target.extraOptions
   ]);