Whether to execute builds inside cgroups.

Cgroups are required and enabled automatically for derivations that require the uid-range system feature.

Cgroups requires a cgroup delegation according to https://systemd.io/CGROUP_DELEGATION/, i.e. the Nix process (nix-daemon or any single user command) should run in a cgroup tree of a parent cgroup which possess the user.delegate=1 extended attribute.

In this scenario, Nix will run builds in a sibling cgroup named nix-build-uid-<build user uid>.

Be aware that this option is incompatible with various nix-build, nix-store, nix store, and nix verify sub-commands when using a local store which will need the option explicitely turned off with the argument --no-use-cgroups.