nixos-rebuild: add --no-ssh-tty flag (#339388)

pkgs/os-specific/linux/nixos-rebuild/_nixos-rebuild

@@ -36,6 +36,7 @@ _nixos-rebuild() {
     --rollback
     --specialisation -c # name
     --use-remote-sudo
+    --no-ssh-tty
     --build-host # host
     --target-host # host
     # Used with list-generations

pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.8

@@ -37,6 +37,7 @@
 .Op Fl -build-host Va host
 .Op Fl -target-host Va host
 .Op Fl -use-remote-sudo
+.Op Fl -no-ssh-tty
 .br
 .Op Fl -verbose | v
 .Op Fl -quiet
@@ -392,6 +393,16 @@ system with
 .Ic sudo Ns
 \&. Setting this option allows deploying as a non-root user.
 .
+.It Fl -no-ssh-tty
+When set, nixos-rebuild will not request a tty when executing commands on the
+.Fl -target-host
+system with
+.Ic ssh Ns
+\&. This may help avoid corrupted terminal output when running multiple
+nixos-rebuild commands in parallel, but may also prevent the remote
+.Ic sudo
+from working properly.
+.
 .It Fl -file Ar path , Fl f Ar path
 Enable and build the NixOS system from the specified file. The file must
 evaluate to an attribute set, and it must contain a valid NixOS configuration

pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh

@@ -32,6 +32,7 @@ specialisation=
 buildHost=
 targetHost=
 remoteSudo=
+noSSHTTY=
 verboseScript=
 noFlake=
 attr=
@@ -163,6 +164,9 @@ while [ "$#" -gt 0 ]; do
       --use-remote-sudo)
         remoteSudo=1
         ;;
+      --no-ssh-tty)
+        noSSHTTY=1
+        ;;
       --flake)
         flake="$1"
         shift 1
@@ -238,12 +242,18 @@ targetHostCmd() {
 }
 
 targetHostSudoCmd() {
+    local t=
+    if [[ ! "${noSSHTTY:-x}" = 1 ]]; then
+        t="-t"
+    fi
+
     if [ -n "$remoteSudo" ]; then
-        useSudo=1 SSHOPTS="$SSHOPTS -t" targetHostCmd "$@"
+        useSudo=1 SSHOPTS="$SSHOPTS $t" targetHostCmd "$@"
     else
         # While a tty might not be necessary, we apply it to be consistent with
         # sudo usage, and an experience that is more consistent with local deployment.
-        SSHOPTS="$SSHOPTS -t" targetHostCmd "$@"
+        # But if the user really doesn't want it, don't do it.
+        SSHOPTS="$SSHOPTS $t" targetHostCmd "$@"
     fi
 }