scripts/deploy: add --build flag

useful as e.g. deploy --pre --build, to only *build* all variants/hosts, but don't actually copy

scripts/deploy

@@ -8,6 +8,7 @@ usage() {
   echo ""
   echo "usage: deploy [options] [host] [host2 ...]"
   echo "options:"
+  echo "- --build: only build; don't copy or deploy"
   echo "- --copy: only build + copy files, nothing more"
   echo "- --switch  (default)"
   echo "- --test: switch to the new configuration, but do not make it bootable"
@@ -68,7 +69,7 @@ parseArgs() {
     local arg=$1
     shift
     case "$arg" in
-      (--copy|--switch|--test)
+      (--build|--copy|--switch|--test)
         action=${arg/--/}
         ;;
       (--deriv)
@@ -221,6 +222,8 @@ deployOneHost() {
 
   local netHost=$(resolveHost "$host")
 
+  case "$action" in
+    (copy|switch|test)
       if [ -n "$host" ] && [ "$host" != "$SELF" ]; then
         if [ -e /run/secrets/nix_signing_key ]; then
           info "signing store paths ..."
@@ -233,8 +236,11 @@ deployOneHost() {
         #   we already have all paths here, and the remote substitution is slow to check and SERIOUSLY flaky on moby in particular.
         ECHO_CMD=1 destructive timeout "$timeout" nix copy -vv --option builders-use-substitutes false --to "ssh-ng://$netHost" "$myStorePath" || return 1
       fi
+      ;;
+  esac
 
-  if [ -n "$action" ] && [ "$action" != "copy" ]; then
+  case "$action" in
+    (switch|test)
       info "activating profile... "
       destructive runOnTarget "$netHost" sudo nix-env -p /nix/var/nix/profiles/system --set "$myStorePath" || return 1
       destructive runOnTarget "$netHost" sudo "$myStorePath/bin/switch-to-configuration" "$action"
@@ -244,7 +250,8 @@ deployOneHost() {
         destructive runOnTarget "$netHost" sane-reboot "$host" || return 1
       fi
       return $rc
-  fi
+      ;;
+  esac
 }
 
 failedDeploys=()