add confirmation prompt when installing

checks/installation/flake-module.nix

@@ -107,7 +107,7 @@ in
                 client.succeed("${pkgs.coreutils}/bin/install -Dm 600 ${../lib/ssh/privkey} /root/.ssh/id_ed25519")
                 client.wait_until_succeeds("ssh -o StrictHostKeyChecking=accept-new -v root@target hostname")
 
-                client.succeed("clan --debug --flake ${../..} machines install test_install_machine root@target >&2")
+                client.succeed("clan --debug --flake ${../..} machines install --yes test_install_machine root@target >&2")
                 try:
                   target.shutdown()
                 except BrokenPipeError:

pkgs/clan-cli/clan_cli/machines/install.py

@@ -63,6 +63,7 @@ class InstallOptions:
     machine: str
     target_host: str
     kexec: str | None
+    confirm: bool
 
 
 def install_command(args: argparse.Namespace) -> None:
@@ -71,10 +72,16 @@ def install_command(args: argparse.Namespace) -> None:
         machine=args.machine,
         target_host=args.target_host,
         kexec=args.kexec,
+        confirm=not args.yes,
     )
     machine = Machine(opts.machine, flake=opts.flake)
     machine.target_host_address = opts.target_host
 
+    if opts.confirm:
+        ask = input(f"Install {machine.name} to {opts.target_host}? [y/N] ")
+        if ask != "y":
+            return
+
     install_nixos(machine, kexec=opts.kexec)
 
 
@@ -84,6 +91,12 @@ def register_install_parser(parser: argparse.ArgumentParser) -> None:
         type=str,
         help="use another kexec tarball to bootstrap NixOS",
     )
+    parser.add_argument(
+        "--yes",
+        action="store_true",
+        help="do not ask for confirmation",
+        default=False,
+    )
     parser.add_argument(
         "machine",
         type=str,