Make node deploy support --dry-run and --ephemeral

Author: hgl

pkgs/nixverse/nixverse.sh

@@ -287,19 +287,21 @@ Deploy one or more nodes.
 
 Options:
   -p, --parallel <num>      number of nodes to deploy in parallel (default: 10)
+  -n, --dry-run             use {nixos,darwin}-rebuild build
+  --ephemeral               use nixos-rebuild test
   --reboot                  deploy with nixos-rebuild boot, then reboot
   -h, --help                show this help
 EOF
 }
 cmd_node_deploy() {
 	local args
-	args=$(getopt -n nixverse -o 'hp:' --long 'help,parallel:,no-activate,no-boot,reboot' -- "$@")
+	args=$(getopt -n nixverse -o 'hnp:' --long 'help,dry-run,parallel:,ephemeral,reboot' -- "$@")
 	eval set -- "$args"
 	unset args
 
 	local parallel=$default_parallel
-	local activate=true
-	local boot=true
+	local dryRun=false
+	local ephemeral=false
 	local reboot=false
 	while true; do
 		case $1 in
@@ -311,12 +313,12 @@ cmd_node_deploy() {
 			fi
 			shift 2
 			;;
-		--no-activate)
-			activate=false
+		-n | --dry-run)
+			dryRun=true
 			shift
 			;;
-		--no-boot)
-			boot=false
+		--ephemeral)
+			ephemeral=true
 			shift
 			;;
 		--reboot)
@@ -338,6 +340,21 @@ cmd_node_deploy() {
 		esac
 	done
 
+	local deployModes=0
+	if [[ $dryRun = true ]]; then
+		deployModes=$((deployModes + 1))
+	fi
+	if [[ $ephemeral = true ]]; then
+		deployModes=$((deployModes + 1))
+	fi
+	if [[ $reboot = true ]]; then
+		deployModes=$((deployModes + 1))
+	fi
+	if ((deployModes > 1)); then
+		echo >&2 "--dry-run, --ephemeral, and --reboot are mutually exclusive"
+		return 1
+	fi
+
 	if [[ $# = 0 ]]; then
 		cmd help node deploy >&2
 		return 1
@@ -380,8 +397,8 @@ in
       inherit nodeNames;
       userFlakeSourcePath = "$flake";
       nixversePath = "@out@";
-      activate = $activate;
-      boot = $boot;
+      dryRun = $dryRun;
+      ephemeral = $ephemeral;
       reboot = $reboot;
     }
   );

pkgs/nixverse/output.nix

@@ -222,8 +222,8 @@
       nodeNames,
       userFlakeSourcePath,
       nixversePath,
-      activate,
-      boot,
+      dryRun,
+      ephemeral,
       reboot,
     }:
     let
@@ -247,16 +247,18 @@
         sshOpts = map (opt: "-o ${lib.escapeShellArg opt}") node.deploy.sshOpts;
         common = "--flake '${userFlakePath}#${nodeName}' --show-trace";
         rebuildAction =
-          if reboot then
+          if dryRun then
+            "build"
+          else if ephemeral then
+            "test"
+          else if reboot then
             "boot"
-          else if activate then
-            if boot then "switch" else "test"
           else
-            "build";
+            "switch";
         rebuild =
           {
             nixos = "NIX_SSHOPTS=${lib.escapeShellArg sshOpts} nixos-rebuild ${rebuildAction} ${targetHost} ${buildHost} ${useSubstitutes} ${useRemoteSudo} ${common}";
-            darwin = "sudo darwin-rebuild ${if activate then "switch" else "build"} ${common}";
+            darwin = "sudo darwin-rebuild ${if dryRun then "build" else "switch"} ${common}";
           }
           .${node.os};
         rebootCommand =
@@ -266,8 +268,11 @@
             "reboot";
       in
       assert lib.assertMsg (
-        !reboot || node.os == "nixos"
-      ) "--reboot is only supported for NixOS node ${nodeName}";
+        reboot -> node.os == "nixos"
+      ) "--reboot is only supported for a NixOS node, which ${nodeName} is not";
+      assert lib.assertMsg (
+        ephemeral -> node.os == "nixos"
+      ) "--ephemeral is only supported for a NixOS node, which ${nodeName} is not";
       {
         name = nodeName;
         command = lib.concatLines (