This option behaves exactly like `boot.extraModprobeConfig`, except that it also includes the generated modprobe.d file in the initrd.
Many years ago, someone tried to include the normal modprobe.d/nixos.conf file generated by `boot.extraModprobeConfig` in the initrd: 0aa2c1dc46. This file contains a reference to a directory with firmware files inside. Including firmware in the initrd made it too big, so the commit was reverted again in 4a4c051a95.
The `boot.extraModprobeConfig` option not changing the initrd caused me much confusion because I tried to set the maximum cache size for ZFS and it didn't work.
Closes https://github.com/NixOS/nixpkgs/issues/25456.
This solves the problem that modprobe does not know about $MODULE_DIR
when run via sudo, and instead wrongly tries to read /lib/modules/:
$ sudo strace -efile modprobe foo |& grep modules
open("/lib/modules/3.14.37/modules.softdep", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/lib/modules/3.14.37/modules.dep.bin", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/lib/modules/3.14.37/modules.dep.bin", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/lib/modules/3.14.37/modules.alias.bin", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
Without this patch, one would have to use sudo -E (preserves environment
vars). But that option is reserved for sudo users with extra rights
(SETENV), so it's not a solution.
environment.sessionVariables are set by PAM, so they are included in the
environment used by sudo.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
You can now say:
systemd.containers.foo.config =
{ services.openssh.enable = true;
services.openssh.ports = [ 2022 ];
users.extraUsers.root.openssh.authorizedKeys.keys = [ "ssh-dss ..." ];
};
which defines a NixOS instance with the given configuration running
inside a lightweight container.
You can also manage the configuration of the container independently
from the host:
systemd.containers.foo.path = "/nix/var/nix/profiles/containers/foo";
where "path" is a NixOS system profile. It can be created/updated by
doing:
$ nix-env --set -p /nix/var/nix/profiles/containers/foo \
-f '<nixos>' -A system -I nixos-config=foo.nix
The container configuration (foo.nix) should define
boot.isContainer = true;
to optimise away the building of a kernel and initrd. This is done
automatically when using the "config" route.
On the host, a lightweight container appears as the service
"container-<name>.service". The container is like a regular NixOS
(virtual) machine, except that it doesn't have its own kernel. It has
its own root file system (by default /var/lib/containers/<name>), but
shares the Nix store of the host (as a read-only bind mount). It also
has access to the network devices of the host.
Currently, if the configuration of the container changes, running
"nixos-rebuild switch" on the host will cause the container to be
rebooted. In the future we may want to send some message to the
container so that it can activate the new container configuration
without rebooting.
Containers are not perfectly isolated yet. In particular, the host's
/sys/fs/cgroup is mounted (writable!) in the guest.
