refactor: break out a helper in fs.nix for mounting remote home dirs

hosts/common/fs.nix

@@ -1,9 +1,10 @@
 # docs
 # - x-systemd options: <https://www.freedesktop.org/software/systemd/man/systemd.mount.html>
 
-{ pkgs, sane-lib, ... }:
+{ lib, pkgs, sane-lib, ... }:
 
-let fsOpts = rec {
+let
+  fsOpts = rec {
     common = [
       "_netdev"
       "noatime"
@@ -54,9 +55,19 @@ let fsOpts = rec {
       "timeo=15"
       "nofail"  # don't fail remote-fs.target when this mount fails  (not an option for sshfs else would be common)
     ];
-};
+  };
+  remoteHome = host: {
+    fileSystems."/mnt/${host}-home" = {
+      device = "colin@${host}:/home/colin";
+      fsType = "fuse.sshfs";
+      options = fsOpts.sshColin ++ fsOpts.noauto;
+      noCheck = true;
+    };
+    sane.fs."/mnt/${host}-home" = sane-lib.fs.wantedDir;
+  };
 in
-{
+lib.mkMerge [
+  {
     # some services which use private directories error if the parent (/var/lib/private) isn't 700.
     sane.fs."/var/lib/private".dir.acl.mode = "0700";
 
@@ -108,22 +119,6 @@ in
     # };
     sane.fs."/mnt/servo-media" = sane-lib.fs.wantedSymlinkTo "/mnt/servo-nfs/media";
 
-  fileSystems."/mnt/desko-home" = {
-    device = "colin@desko:/home/colin";
-    fsType = "fuse.sshfs";
-    options = fsOpts.sshColin ++ fsOpts.noauto;
-    noCheck = true;
-  };
-  sane.fs."/mnt/desko-home" = sane-lib.fs.wantedDir;
-
-  fileSystems."/mnt/moby-home" = {
-    device = "colin@moby-hn:/home/colin";
-    fsType = "fuse.sshfs";
-    options = fsOpts.sshColin ++ fsOpts.noauto;
-    noCheck = true;
-  };
-  sane.fs."/mnt/moby-home" = sane-lib.fs.wantedDir;
-
     environment.pathsToLink = [
       # needed to achieve superuser access for user-mounted filesystems (see optionsRoot above)
       # we can only link whole directories here, even though we're only interested in pkgs.openssh
@@ -133,5 +128,9 @@ in
     environment.systemPackages = [
       pkgs.sshfs-fuse
     ];
-}
+  }
+
+  (remoteHome "desko")
+  (remoteHome "moby")
+]