nixpkgs/nixos/modules/virtualisation/containers.nix
Eelco Dolstra 333bfe16c4 Containers: Support setting up macvlan interfaces
By setting a line like

  MACVLANS="eno1"

in /etc/containers/<name>.conf, the container will get an Ethernet
interface named mv-eno1, which represents an additional MAC address on
the physical eno1 interface. Thus the container has direct access to
the physical network. You can specify multiple interfaces in MACVLANS.

Unfortunately, you can't do this with wireless interfaces.

Note that dhcpcd is disabled in containers by default, so you'll
probably want to set

  networking.useDHCP = true;

in the container, or configure a static IP address.

To do: add a containers.* option for this, and a flag for
"nixos-container create".
2014-05-07 17:53:57 +02:00

295 lines
9.4 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
nixos-container = pkgs.substituteAll {
name = "nixos-container";
dir = "bin";
isExecutable = true;
src = ./nixos-container.pl;
perl = "${pkgs.perl}/bin/perl -I${pkgs.perlPackages.FileSlurp}/lib/perl5/site_perl";
inherit (pkgs) socat;
};
# The container's init script, a small wrapper around the regular
# NixOS stage-2 init script.
containerInit = pkgs.writeScript "container-init"
''
#! ${pkgs.stdenv.shell} -e
# Initialise the container side of the veth pair.
if [ "$PRIVATE_NETWORK" = 1 ]; then
ip link set host0 name eth0
ip link set dev eth0 up
if [ -n "$HOST_ADDRESS" ]; then
ip route add $HOST_ADDRESS dev eth0
ip route add default via $HOST_ADDRESS
fi
if [ -n "$LOCAL_ADDRESS" ]; then
ip addr add $LOCAL_ADDRESS dev eth0
fi
fi
exec "$1"
'';
system = config.nixpkgs.system;
in
{
options = {
boot.isContainer = mkOption {
type = types.bool;
default = false;
description = ''
Whether this NixOS machine is a lightweight container running
in another NixOS system.
'';
};
containers = mkOption {
type = types.attrsOf (types.submodule (
{ config, options, name, ... }:
{
options = {
config = mkOption {
description = ''
A specification of the desired configuration of this
container, as a NixOS module.
'';
};
path = mkOption {
type = types.path;
example = "/nix/var/nix/profiles/containers/webserver";
description = ''
As an alternative to specifying
<option>config</option>, you can specify the path to
the evaluated NixOS system configuration, typically a
symlink to a system profile.
'';
};
privateNetwork = mkOption {
type = types.bool;
default = false;
description = ''
Whether to give the container its own private virtual
Ethernet interface. The interface is called
<literal>eth0</literal>, and is hooked up to the interface
<literal>ve-<replaceable>container-name</replaceable></literal>
on the host. If this option is not set, then the
container shares the network interfaces of the host,
and can bind to any port on any interface.
'';
};
hostAddress = mkOption {
type = types.nullOr types.string;
default = null;
example = "10.231.136.1";
description = ''
The IPv4 address assigned to the host interface.
'';
};
localAddress = mkOption {
type = types.nullOr types.string;
default = null;
example = "10.231.136.2";
description = ''
The IPv4 address assigned to <literal>eth0</literal>
in the container.
'';
};
};
config = mkMerge
[ (mkIf options.config.isDefined {
path = (import ../../lib/eval-config.nix {
inherit system;
modules =
let extraConfig =
{ boot.isContainer = true;
security.initialRootPassword = mkDefault "!";
networking.hostName = mkDefault name;
networking.useDHCP = false;
};
in [ extraConfig config.config ];
prefix = [ "containers" name ];
}).config.system.build.toplevel;
})
];
}));
default = {};
example = literalExample
''
{ webserver =
{ path = "/nix/var/nix/profiles/webserver";
};
database =
{ config =
{ config, pkgs, ... }:
{ services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql92;
};
};
}
'';
description = ''
A set of NixOS system configurations to be run as lightweight
containers. Each container appears as a service
<literal>container-<replaceable>name</replaceable></literal>
on the host system, allowing it to be started and stopped via
<command>systemctl</command> .
'';
};
};
config = mkIf (!config.boot.isContainer) {
systemd.services."container@" =
{ description = "Container '%i'";
unitConfig.RequiresMountsFor = [ "/var/lib/containers/%i" ];
path = [ pkgs.iproute ];
environment.INSTANCE = "%i";
environment.root = "/var/lib/containers/%i";
preStart =
''
mkdir -p -m 0755 $root/var/lib
# Create a named pipe to get a signal when the container
# has finished booting.
rm -f $root/var/lib/startup-done
mkfifo -m 0600 $root/var/lib/startup-done
'';
script =
''
mkdir -p -m 0755 "$root/etc" "$root/var/lib"
if ! [ -e "$root/etc/os-release" ]; then
touch "$root/etc/os-release"
fi
mkdir -p -m 0755 \
"/nix/var/nix/profiles/per-container/$INSTANCE" \
"/nix/var/nix/gcroots/per-container/$INSTANCE"
if [ "$PRIVATE_NETWORK" = 1 ]; then
extraFlags+=" --network-veth"
fi
for iface in $MACVLANS; do
extraFlags+=" --network-macvlan=$iface"
done
# If the host is 64-bit and the container is 32-bit, add a
# --personality flag.
${optionalString (config.nixpkgs.system == "x86_64-linux") ''
if [ "$(< ''${SYSTEM_PATH:-/nix/var/nix/profiles/per-container/$INSTANCE/system}/system)" = i686-linux ]; then
extraFlags+=" --personality=x86"
fi
''}
exec ${config.systemd.package}/bin/systemd-nspawn \
--keep-unit \
-M "$INSTANCE" -D "$root" $extraFlags \
--bind-ro=/nix/store \
--bind-ro=/nix/var/nix/db \
--bind-ro=/nix/var/nix/daemon-socket \
--bind="/nix/var/nix/profiles/per-container/$INSTANCE:/nix/var/nix/profiles" \
--bind="/nix/var/nix/gcroots/per-container/$INSTANCE:/nix/var/nix/gcroots" \
--setenv PRIVATE_NETWORK="$PRIVATE_NETWORK" \
--setenv HOST_ADDRESS="$HOST_ADDRESS" \
--setenv LOCAL_ADDRESS="$LOCAL_ADDRESS" \
--setenv PATH="$PATH" \
${containerInit} "''${SYSTEM_PATH:-/nix/var/nix/profiles/system}/init"
'';
postStart =
''
# This blocks until the container-startup-done service
# writes something to this pipe. FIXME: it also hangs
# until the start timeout expires if systemd-nspawn exits.
read x < $root/var/lib/startup-done
rm -f $root/var/lib/startup-done
if [ "$PRIVATE_NETWORK" = 1 ]; then
ifaceHost=ve-$INSTANCE
ip link set dev $ifaceHost up
if [ -n "$HOST_ADDRESS" ]; then
ip addr add $HOST_ADDRESS dev $ifaceHost
fi
if [ -n "$LOCAL_ADDRESS" ]; then
ip route add $LOCAL_ADDRESS dev $ifaceHost
fi
fi
'';
preStop =
''
machinectl poweroff "$INSTANCE"
'';
restartIfChanged = false;
#reloadIfChanged = true; # FIXME
serviceConfig.ExecReload = pkgs.writeScript "reload-container"
''
#! ${pkgs.stdenv.shell} -e
SYSTEM_PATH=/nix/var/nix/profiles/system
echo $SYSTEM_PATH/bin/switch-to-configuration test | \
${pkgs.socat}/bin/socat unix:$root/var/lib/run-command.socket -
'';
serviceConfig.SyslogIdentifier = "container %i";
serviceConfig.EnvironmentFile = "-/etc/containers/%i.conf";
};
# Generate a configuration file in /etc/containers for each
# container so that container@.target can get the container
# configuration.
environment.etc = mapAttrs' (name: cfg: nameValuePair "containers/${name}.conf"
{ text =
''
SYSTEM_PATH=${cfg.path}
${optionalString cfg.privateNetwork ''
PRIVATE_NETWORK=1
${optionalString (cfg.hostAddress != null) ''
HOST_ADDRESS=${cfg.hostAddress}
''}
${optionalString (cfg.localAddress != null) ''
LOCAL_ADDRESS=${cfg.localAddress}
''}
''}
'';
}) config.containers;
# FIXME: auto-start containers.
# Generate /etc/hosts entries for the containers.
networking.extraHosts = concatStrings (mapAttrsToList (name: cfg: optionalString (cfg.localAddress != null)
''
${cfg.localAddress} ${name}.containers
'') config.containers);
networking.dhcpcd.denyInterfaces = [ "ve-*" ];
environment.systemPackages = [ nixos-container ];
};
}