In the past, it tried direct access if it *could* [1] perform direct
access.
This solves a bunch of errors people had when they tried the cgroup
feature and their scripts did not pass NIX_REMOTE=daemon manually
(nixos-rebuild-ng, home-manager activation from a root systemd unit,
etc.)
To avoid looping infinitely while receiving daemon connections, we
forcibly change the store URI when forking for a subdaemon to do direct
access automatically, this doesn't break forward usecases where you
point a daemon to another socket because we only change NIX_REMOTE="",
NIX_REMOTE=daemon, NIX_REMOTE=auto to a local and direct access.
All these usecases would end up infinitely looping no matter what
settings are set, because we are also responsible for creating the
daemon socket.
[1]: this happened all the time if you were `root`.
Related: https://github.com/NixOS/nixpkgs/pull/415701
Change-Id: I783fc795a9c2ee25b3d9f44f453f8f94b063371f
Signed-off-by: Raito Bezarius <raito@lix.systems>
When Ctrl-C is sent to the workload, even across remote builds, the
whole process possess a global flag `_isInterrupted` which is checked in
certain filesystem operations, cancelling them, e.g. writeFile will
write nothing under interruption unwinding.
In addition, if any operation throws an exception before we `rmdir` the
cgroup, we may leave it hanging while we remove the state record.
Therefore, we put the final cleanup in a block.
In practice, reading statistics could lead to failures.
Control groups cleanups are critical though and should always be
performed.
Change-Id: I48fa87317b6a9f6663559bc8fa5f8a897f37011e
Signed-off-by: Raito Bezarius <raito@lix.systems>
We offer full cgroup delegation to our sandbox now, required for running
containers inside the sandbox.
To run systemd-nspawn or containers managers inside the sandbox, there
is a need for one extra ingredient now: control over your own cgroup
subtree inside the sandbox.
If, in addition, you need multiple UIDs, for e.g. rootless usecases, you
need to run with the `uid-range` system feature.
Therefore, when the daemon or Nix runs under the right condition, e.g.
systemd-style delegation of the cgroup subtree while placing the
nix-daemon in a supervisor sub-cgroup, we create a new sub-cgroup for
each build based on the build UID and delegate that sub-cgroup to the
builder's process.
Additionally, `uid-range` always request the `cgroups` feature now, as
`uid-range` builds would probably always benefit from having cgroups
delegated, but the converse is not true.
Inspired from https://github.com/NixOS/nix/pull/11412 with a different
design that does not use function-local statics to derive the root
cgroup.
Co-authored-by: Linus Heckemann <git@sphalerite.org>
Co-authored-by: Parker Hoyes <contact@parkerhoyes.com>
Change-Id: Ic8947c5adaf4b5bbd153386e05fad65a935274fa
Signed-off-by: Raito Bezarius <raito@lix.systems>
