nixpkgs/nixos/modules/services/hardware/udev.nix
Eelco Dolstra 9ee30cd9b5 Add support for lightweight NixOS containers
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.
2013-11-27 17:14:10 +01:00

248 lines
7.9 KiB
Nix

{ config, pkgs, ... }:
with pkgs.lib;
let
inherit (pkgs) stdenv writeText procps;
udev = config.systemd.package;
cfg = config.services.udev;
extraUdevRules = pkgs.writeTextFile {
name = "extra-udev-rules";
text = cfg.extraRules;
destination = "/etc/udev/rules.d/10-local.rules";
};
nixosRules = ''
# Miscellaneous devices.
KERNEL=="kvm", MODE="0666"
KERNEL=="kqemu", MODE="0666"
'';
# Perform substitutions in all udev rules files.
udevRules = stdenv.mkDerivation {
name = "udev-rules";
buildCommand = ''
mkdir -p $out
shopt -s nullglob
# Set a reasonable $PATH for programs called by udev rules.
echo 'ENV{PATH}="${udevPath}/bin:${udevPath}/sbin"' > $out/00-path.rules
# Add the udev rules from other packages.
for i in ${toString cfg.packages}; do
echo "Adding rules for package $i"
for j in $i/{etc,lib}/udev/rules.d/*; do
echo "Copying $j to $out/$(basename $j)"
cat $j > $out/$(basename $j)
done
done
# Fix some paths in the standard udev rules. Hacky.
for i in $out/*.rules; do
substituteInPlace $i \
--replace \"/sbin/modprobe \"${config.system.sbin.modprobe}/sbin/modprobe \
--replace \"/sbin/mdadm \"${pkgs.mdadm}/sbin/mdadm \
--replace \"/sbin/blkid \"${pkgs.utillinux}/sbin/blkid \
--replace \"/bin/mount \"${pkgs.utillinux}/bin/mount
done
echo -n "Checking that all programs called by relative paths in udev rules exist in ${udev}/lib/udev... "
import_progs=$(grep 'IMPORT{program}="[^/$]' $out/* |
sed -e 's/.*IMPORT{program}="\([^ "]*\)[ "].*/\1/' | uniq)
run_progs=$(grep -v '^[[:space:]]*#' $out/* | grep 'RUN+="[^/$]' |
sed -e 's/.*RUN+="\([^ "]*\)[ "].*/\1/' | uniq)
for i in $import_progs $run_progs; do
if [[ ! -x ${pkgs.udev}/lib/udev/$i && ! $i =~ socket:.* ]]; then
echo "FAIL"
echo "$i is called in udev rules but not installed by udev"
exit 1
fi
done
echo "OK"
echo -n "Checking that all programs called by absolute paths in udev rules exist... "
import_progs=$(grep 'IMPORT{program}="\/' $out/* |
sed -e 's/.*IMPORT{program}="\([^ "]*\)[ "].*/\1/' | uniq)
run_progs=$(grep -v '^[[:space:]]*#' $out/* | grep 'RUN+="/' |
sed -e 's/.*RUN+="\([^ "]*\)[ "].*/\1/' | uniq)
for i in $import_progs $run_progs; do
if [[ ! -x $i ]]; then
echo "FAIL"
echo "$i is called in udev rules but not installed by udev"
exit 1
fi
done
echo "OK"
echo "Consider fixing the following udev rules:"
for i in ${toString cfg.packages}; do
grep -l '\(RUN+\|IMPORT{program}\)="\(/usr\)\?/s\?bin' $i/*/udev/rules.d/* || true
done
${optionalString (!config.networking.usePredictableInterfaceNames) ''
ln -s /dev/null $out/80-net-name-slot.rules
''}
# If auto-configuration is disabled, then remove
# udev's 80-drivers.rules file, which contains rules for
# automatically calling modprobe.
${optionalString (!config.boot.hardwareScan) ''
ln -s /dev/null $out/80-drivers.rules
''}
''; # */
};
# Udev has a 512-character limit for ENV{PATH}, so create a symlink
# tree to work around this.
udevPath = pkgs.buildEnv {
name = "udev-path";
paths = cfg.path;
pathsToLink = [ "/bin" "/sbin" ];
ignoreCollisions = true;
};
in
{
###### interface
options = {
boot.hardwareScan = mkOption {
type = types.bool;
default = true;
description = ''
Whether to try to load kernel modules for all detected hardware.
Usually this does a good job of providing you with the modules
you need, but sometimes it can crash the system or cause other
nasty effects.
'';
};
services.udev = {
packages = mkOption {
type = types.listOf types.path;
default = [];
description = ''
List of packages containing <command>udev</command> rules.
All files found in
<filename><replaceable>pkg</replaceable>/etc/udev/rules.d</filename> and
<filename><replaceable>pkg</replaceable>/lib/udev/rules.d</filename>
will be included.
'';
};
path = mkOption {
type = types.listOf types.path;
default = [];
description = ''
Packages added to the <envar>PATH</envar> environment variable when
executing programs from Udev rules.
'';
};
extraRules = mkOption {
default = "";
example = ''
KERNEL=="eth*", ATTR{address}=="00:1D:60:B9:6D:4F", NAME="my_fast_network_card"
'';
type = types.lines;
description = ''
Additional <command>udev</command> rules. They'll be written
into file <filename>10-local.rules</filename>. Thus they are
read before all other rules.
'';
};
};
hardware.firmware = mkOption {
type = types.listOf types.path;
default = [];
example = [ "/root/my-firmware" ];
description = ''
List of directories containing firmware files. Such files
will be loaded automatically if the kernel asks for them
(i.e., when it has detected specific hardware that requires
firmware to function). If more than one path contains a
firmware file with the same name, the first path in the list
takes precedence. Note that you must rebuild your system if
you add files to any of these directories. For quick testing,
put firmware files in /root/test-firmware and add that
directory to the list.
Note that you can also add firmware packages to this
list as these are directories in the nix store.
'';
apply = list: pkgs.buildEnv {
name = "firmware";
paths = list;
pathsToLink = [ "/" ];
ignoreCollisions = true;
};
};
networking.usePredictableInterfaceNames = mkOption {
default = true;
type = types.bool;
description = ''
Whether to assign <link
xlink:href='http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames'>predictable
names to network interfaces</link>. If enabled, interfaces
are assigned names that contain topology information
(e.g. <literal>wlp3s0</literal>) and thus should be stable
across reboots. If disabled, names depend on the order in
which interfaces are discovered by the kernel, which may
change randomly across reboots; for instance, you may find
<literal>eth0</literal> and <literal>eth1</literal> flipping
unpredictably.
'';
};
};
###### implementation
config = mkIf (!config.boot.isContainer) {
services.udev.extraRules = nixosRules;
services.udev.packages = [ extraUdevRules ];
services.udev.path = [ pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.utillinux udev ];
environment.etc =
[ { source = udevRules;
target = "udev/rules.d";
}
];
system.requiredKernelConfig = with config.lib.kernelConfig; [
(isEnabled "UNIX")
(isYes "INOTIFY_USER")
(isYes "NET")
];
boot.extraModprobeConfig = "options firmware_class path=${config.hardware.firmware}";
system.activationScripts.udevd =
''
echo "" > /proc/sys/kernel/hotplug
# Regenerate the hardware database /var/lib/udev/hwdb.bin
# whenever systemd changes.
if [ ! -e /var/lib/udev/prev-systemd -o "$(readlink /var/lib/udev/prev-systemd)" != ${config.systemd.package} ]; then
echo "regenerating udev hardware database..."
${config.systemd.package}/bin/udevadm hwdb --update && ln -sfn ${config.systemd.package} /var/lib/udev/prev-systemd
fi
'';
};
}