depot/third_party/nixpkgs/doc/builders/special/darwin-builder.section.md

darwin.builder

darwin.builder provides a way to bootstrap a Linux builder on a macOS machine.

This requires macOS version 12.4 or later.

This also requires that port 22 on your machine is free (since Nix does not permit specifying a non-default SSH port for builders).

You will also need to be a trusted user for your Nix installation. In other words, your /etc/nix/nix.conf should have something like:

extra-trusted-users = <your username goes here>

To launch the builder, run the following flake:

$ nix run nixpkgs#darwin.builder

That will prompt you to enter your sudo password:

+ sudo --reset-timestamp /nix/store/…-install-credentials.sh ./keys
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 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: builder (automatic login)


[builder@nixos:~]$

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:

# - Replace ${ARCH} with either aarch64 or x86_64 to match your host machine
# - Replace ${MAX_JOBS} with the maximum number of builds (pick 4 if you're not sure)
builders = ssh-ng://builder@localhost ${ARCH}-linux /etc/nix/builder_ed25519 ${MAX_JOBS} - - - c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUpCV2N4Yi9CbGFxdDFhdU90RStGOFFVV3JVb3RpQzVxQkorVXVFV2RWQ2Igcm9vdEBuaXhvcwo=

# Not strictly necessary, but this will reduce your disk utilization
builders-use-substitutes = true

… and then restart your Nix daemon to apply the change:

$ sudo launchctl kickstart -k system/org.nixos.nix-daemon