Building for NixOS

Install Nix, the package manager. The easiest way is to use the installer, with either the multi-user or single-user installation (your choice).
Tell mach to use Nix: export MACH_USE_NIX=
Type nix-shell to enter a shell with all of the necessary tools and dependencies.
Install the other dependencies: ./mach bootstrap
Build servoshell: ./mach build

Troubleshooting

Be sure to look at the General Troubleshooting section if you have trouble with your build and your problem is not listed below.

error: getting status of /nix/var/nix/daemon-socket/socket: Permission denied

If you get this error and you’ve installed Nix with your system package manager:

Add yourself to the nix-users group
Log out and log back in

error: file 'nixpkgs' was not found in the Nix search path (add it using $NIX_PATH or -I)

This error is harmless, but you can fix it as follows:

Run sudo nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs
Run sudo nix-channel --update