nixpkgs/nixos/modules/virtualisation/docker.nix
Bjørn Forsman 5f17aeb403 nixos/docker: default storageDriver to "devicemapper"
Commit 9bfe92ecee ("docker: Minor improvements, fix failing test") added
the services.docker.storageDriver option, made it mandatory but didn't
give it a default value. This results in an ugly traceback when users
enable docker, if they don't pay enough attention to also set the
storageDriver option. (An attempt was made to add an assertion, but it
didn't work, possibly because of how "mkMerge" works.)

The arguments against a default value were that the optimal value
depends on the filesystem on the host. This is, AFAICT, only in part
true. (It seems some backends are filesystem agnostic.) Also, docker
itself uses a default storage driver, "devicemapper", when no
--storage-driver=x options are given. Hence, we use the same value as
default.

Add a FIXME comment that 'devicemapper' breaks NixOS VM tests (for yet
unknown reasons), so we still run those with the 'overlay' driver.

Closes #10100 and #10217.
2015-10-04 14:34:38 +02:00

142 lines
4.2 KiB
Nix

# Systemd services for docker.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.virtualisation.docker;
pro = config.networking.proxy.default;
proxy_env = optionalAttrs (pro != null) { Environment = "\"http_proxy=${pro}\""; };
in
{
###### interface
options.virtualisation.docker = {
enable =
mkOption {
type = types.bool;
default = false;
description =
''
This option enables docker, a daemon that manages
linux containers. Users in the "docker" group can interact with
the daemon (e.g. to start or stop containers) using the
<command>docker</command> command line tool.
'';
};
socketActivation =
mkOption {
type = types.bool;
default = false;
description =
''
This option enables docker with socket activation. I.e. docker will
start when first called by client.
Note: This is false by default because systemd lower than 214 that
nixos uses so far, doesn't support SocketGroup option, so socket
created by docker has root group now. This will likely be changed
in future. So set this option explicitly to false if you wish.
'';
};
storageDriver =
mkOption {
type = types.enum ["aufs" "btrfs" "devicemapper" "overlay" "zfs"];
default = "devicemapper";
description =
''
This option determines which Docker storage driver to use.
'';
};
extraOptions =
mkOption {
type = types.separatedString " ";
default = "";
description =
''
The extra command-line options to pass to
<command>docker</command> daemon.
'';
};
postStart =
mkOption {
type = types.lines;
default = ''
while ! [ -e /var/run/docker.sock ]; do
sleep 0.1
done
'';
description = ''
The postStart phase of the systemd service. You may need to
override this if you are passing in flags to docker which
don't cause the socket file to be created.
'';
};
};
###### implementation
config = mkIf cfg.enable (mkMerge [
{ environment.systemPackages = [ pkgs.docker ];
users.extraGroups.docker.gid = config.ids.gids.docker;
}
(mkIf cfg.socketActivation {
systemd.services.docker = {
description = "Docker Application Container Engine";
after = [ "network.target" "docker.socket" ];
requires = [ "docker.socket" ];
serviceConfig = {
ExecStart = "${pkgs.docker}/bin/docker daemon --host=fd:// --group=docker --storage-driver=${cfg.storageDriver} ${cfg.extraOptions}";
# I'm not sure if that limits aren't too high, but it's what
# goes in config bundled with docker itself
LimitNOFILE = 1048576;
LimitNPROC = 1048576;
} // proxy_env;
};
systemd.sockets.docker = {
description = "Docker Socket for the API";
wantedBy = [ "sockets.target" ];
socketConfig = {
ListenStream = "/var/run/docker.sock";
SocketMode = "0660";
SocketUser = "root";
SocketGroup = "docker";
};
};
})
(mkIf (!cfg.socketActivation) {
systemd.services.docker = {
description = "Docker Application Container Engine";
wantedBy = [ "multi-user.target" ];
after = [ "network.target" ];
serviceConfig = {
ExecStart = "${pkgs.docker}/bin/docker daemon --group=docker --storage-driver=${cfg.storageDriver} ${cfg.extraOptions}";
# I'm not sure if that limits aren't too high, but it's what
# goes in config bundled with docker itself
LimitNOFILE = 1048576;
LimitNPROC = 1048576;
} // proxy_env;
path = [ pkgs.kmod ] ++ (optional (cfg.storageDriver == "zfs") pkgs.zfs);
environment.MODULE_DIR = "/run/current-system/kernel-modules/lib/modules";
postStart = cfg.postStart;
# Presumably some containers are running we don't want to interrupt
restartIfChanged = false;
};
})
]);
}