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|
{ config, pkgs, ... }:
with pkgs.lib;
{
options = {
boot.isContainer = mkOption {
type = types.bool;
default = false;
description = ''
Whether this NixOS machine is a lightweight container running
in another NixOS system.
'';
};
systemd.containers = mkOption {
type = types.attrsOf (types.submodule (
{ config, options, name, ... }:
{
options = {
root = mkOption {
type = types.path;
description = ''
The root directory of the container.
'';
};
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.
'';
};
};
config = mkMerge
[ { root = mkDefault "/var/lib/containers/${name}";
}
(mkIf options.config.isDefined {
path = (import ../../lib/eval-config.nix {
modules =
let extraConfig =
{ boot.isContainer = true;
security.initialRootPassword = mkDefault "!";
networking.hostName = mkDefault name;
imports = [ ./container-login.nix ];
};
in [ extraConfig config.config ];
prefix = [ "systemd" "containers" name ];
}).config.system.build.toplevel;
})
];
}));
default = {};
example = literalExample
''
{ webserver =
{ root = "/containers/webserver";
path = "/nix/var/nix/profiles/webserver";
};
database =
{ root = "/containers/database";
config =
{ config, pkgs, ... }:
{ services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql92;
};
};
}
'';
description = ''
A set of NixOS system configurations to be run as lightweight
containers. Each container appears as a service
<literal>container-<replaceable>name</replaceable></literal>
on the host system, allowing it to be started and stopped via
<command>systemctl</command> .
'';
};
};
config = {
systemd.services = mapAttrs' (name: container: nameValuePair "container-${name}"
{ description = "Container '${name}'";
wantedBy = [ "multi-user.target" ];
unitConfig.RequiresMountsFor = [ container.root ];
preStart =
''
mkdir -p -m 0755 ${container.root}/etc
if ! [ -e ${container.root}/etc/os-release ]; then
touch ${container.root}/etc/os-release
fi
mkdir -p -m 0755 \
/nix/var/nix/profiles/per-container/${name} \
/nix/var/nix/gcroots/per-container/${name}
'';
serviceConfig.ExecStart =
"${config.systemd.package}/bin/systemd-nspawn"
+ " -M ${name} -D ${container.root}"
+ " --bind-ro=/nix/store --bind-ro=/nix/var/nix/db --bind-ro=/nix/var/nix/daemon-socket"
+ " --bind=/nix/var/nix/profiles/per-container/${name}:/nix/var/nix/profiles"
+ " --bind=/nix/var/nix/gcroots/per-container/${name}:/nix/var/nix/gcroots"
+ " ${container.path}/init";
preStop =
''
pid="$(cat /sys/fs/cgroup/systemd/machine/${name}.nspawn/system/tasks 2> /dev/null)"
if [ -n "$pid" ]; then
# Send the RTMIN+3 signal, which causes the container
# systemd to start halt.target.
echo "killing container systemd, PID = $pid"
kill -RTMIN+3 $pid
# Wait for the container to exit. We can't let systemd
# do this because it will send a signal to the entire
# cgroup.
for ((n = 0; n < 180; n++)); do
if ! kill -0 $pid 2> /dev/null; then break; fi
sleep 1
done
fi
'';
reloadIfChanged = true;
serviceConfig.ExecReload =
"${pkgs.bash}/bin/bash -c '"
+ "echo ${container.path}/bin/switch-to-configuration test "
+ "| ${pkgs.socat}/bin/socat unix:${container.root}/var/lib/root-shell.socket -'";
}) config.systemd.containers;
};
}
|