darwin.builder: auto-login as the `builder` user (#208772)

… as suggested by @NiklasGollenstede in:

https://github.com/NixOS/nixpkgs/pull/206951#issuecomment-1369020601

This simplifies the user experience for logging into and
debugging the machine and also simplifies the instructions for
shutting down the machine gracefully.

1 files changed, 7 insertions, 5 deletions

diff --git a/doc/builders/special/darwin-builder.section.md b/doc/builders/special/darwin-builder.section.md
index af9de5751b2c..3913b692498d 100644
--- a/doc/builders/special/darwin-builder.section.md
+++ b/doc/builders/special/darwin-builder.section.md
@@ -28,19 +28,21 @@ Password:
 ```
 
 … so that it can install a private key used to `ssh` into the build server.
-After that the script will launch the virtual machine:
+After that the script will launch the virtual machine and automatically log you
+in as the `builder` user:
 
 ```
 <<< Welcome to NixOS 22.11.20220901.1bd8d11 (aarch64) - ttyAMA0 >>>
 
 Run 'nixos-help' for the NixOS manual.
 
-nixos login:
+nixos login: builder (automatic login)
+
+
+[builder@nixos:~]$
 ```
 
-> Note: When you need to stop the VM, type `Ctrl`-`a` + `c` to open the `qemu`
-> prompt and then type `system_powerdown` followed by `Enter`, or run `shutdown now`
-> as the `builder` user (e.g. `ssh -i keys/builder_ed25519 builder@localhost shutdown now`)
+> Note: When you need to stop the VM, run `shutdown now` as the `builder` user.
 
 To delegate builds to the remote builder, add the following options to your
 `nix.conf` file: