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Add support for imperative container management

The command nixos-container can now create containers.  For instance,
the following creates and starts a container named ‘database’:

  $ nixos-container create database

The configuration of the container is stored in
/var/lib/containers/<name>/etc/nixos/configuration.nix.  After editing
the configuration, you can make the changes take effect by doing

  $ nixos-container update database

The container can also be destroyed:

  $ nixos-container destroy database

Containers are now executed using a template unit,
‘container@.service’, so the unit in this example would be
‘container@database.service’.
This commit is contained in:
Eelco Dolstra 2014-03-19 19:55:05 +01:00
parent 0cca0f477f
commit ba88db3cd3
2 changed files with 184 additions and 86 deletions

View file

@ -42,13 +42,6 @@ in
{
options = {
root = mkOption {
type = types.path;
description = ''
The root directory of the container.
'';
};
config = mkOption {
description = ''
A specification of the desired configuration of this
@ -103,9 +96,7 @@ in
};
config = mkMerge
[ { root = mkDefault "/var/lib/containers/${name}";
}
(mkIf options.config.isDefined {
[ (mkIf options.config.isDefined {
path = (import ../../lib/eval-config.nix {
modules =
let extraConfig =
@ -126,12 +117,10 @@ in
example = literalExample
''
{ webserver =
{ root = "/containers/webserver";
path = "/nix/var/nix/profiles/webserver";
{ path = "/nix/var/nix/profiles/webserver";
};
database =
{ root = "/containers/database";
config =
{ config =
{ config, pkgs, ... }:
{ services.postgresql.enable = true;
services.postgresql.package = pkgs.postgresql92;
@ -153,78 +142,76 @@ in
config = {
systemd.services = mapAttrs' (name: cfg:
let
# FIXME: interface names have a maximum length.
ifaceHost = "c-${name}";
ifaceCont = "ctmp-${name}";
ns = "net-${name}";
in
nameValuePair "container-${name}" {
description = "Container '${name}'";
systemd.services."container@" =
{ description = "Container '%I'";
wantedBy = [ "multi-user.target" ];
unitConfig.RequiresMountsFor = [ cfg.root ];
unitConfig.RequiresMountsFor = [ "/var/lib/containers/%I" ];
path = [ pkgs.iproute ];
preStart =
environment.INSTANCE = "%I";
script =
''
mkdir -p -m 0755 ${cfg.root}/etc
if ! [ -e ${cfg.root}/etc/os-release ]; then
touch ${cfg.root}/etc/os-release
root="/var/lib/containers/$INSTANCE"
mkdir -p -m 0755 "$root/etc"
if ! [ -e "$root/etc/os-release" ]; then
touch "$root/etc/os-release"
fi
mkdir -p -m 0755 \
/nix/var/nix/profiles/per-container/${name} \
/nix/var/nix/gcroots/per-container/${name}
''
"/nix/var/nix/profiles/per-container/$INSTANCE" \
"/nix/var/nix/gcroots/per-container/$INSTANCE"
+ optionalString (cfg.root != "/var/lib/containers/${name}") ''
ln -sfn "${cfg.root}" "/var/lib/containers/${name}"
''
SYSTEM_PATH=/nix/var/nix/profiles/system
if [ -f "/etc/containers/$INSTANCE.conf" ]; then
. "/etc/containers/$INSTANCE.conf"
fi
+ optionalString cfg.privateNetwork ''
# Cleanup from last time.
ip netns del ${ns} 2> /dev/null || true
ip link del ${ifaceHost} 2> /dev/null || true
ip link del ${ifaceCont} 2> /dev/null || true
ifaceHost=c-$INSTANCE
ifaceCont=ctmp-$INSTANCE
ns=net-$INSTANCE
ip netns del $ns 2> /dev/null || true
ip link del $ifaceHost 2> /dev/null || true
ip link del $ifaceCont 2> /dev/null || true
# Create a pair of virtual ethernet devices. On the host,
# we get c-<container-name, and on the guest, we get
# eth0.
set -x
ip link add ${ifaceHost} type veth peer name ${ifaceCont}
ip netns add ${ns}
ip link set ${ifaceCont} netns ${ns}
ip netns exec ${ns} ip link set ${ifaceCont} name eth0
ip netns exec ${ns} ip link set dev eth0 up
ip link set dev ${ifaceHost} up
${optionalString (cfg.hostAddress != null) ''
ip addr add ${cfg.hostAddress} dev ${ifaceHost}
ip netns exec ${ns} ip route add ${cfg.hostAddress} dev eth0
ip netns exec ${ns} ip route add default via ${cfg.hostAddress}
''}
${optionalString (cfg.localAddress != null) ''
ip netns exec ${ns} ip addr add ${cfg.localAddress} dev eth0
ip route add ${cfg.localAddress} dev ${ifaceHost}
''}
if [ "$PRIVATE_NETWORK" = 1 ]; then
# Create a pair of virtual ethernet devices. On the host,
# we get c-<container-name, and on the guest, we get
# eth0.
ip link add $ifaceHost type veth peer name $ifaceCont
ip netns add $ns
ip link set $ifaceCont netns $ns
ip netns exec $ns ip link set $ifaceCont name eth0
ip netns exec $ns ip link set dev eth0 up
ip link set dev $ifaceHost up
if [ -n "$HOST_ADDRESS" ]; then
ip addr add $HOST_ADDRESS dev $ifaceHost
ip netns exec $ns ip route add $HOST_ADDRESS dev eth0
ip netns exec $ns ip route add default via $HOST_ADDRESS
fi
if [ -n "$LOCAL_ADDRESS" ]; then
ip netns exec $ns ip addr add $LOCAL_ADDRESS dev eth0
ip route add $LOCAL_ADDRESS dev $ifaceHost
fi
runInNetNs="${runInNetns}/bin/run-in-netns $ns"
extraFlags="--capability=CAP_NET_ADMIN"
fi
exec $runInNetNs ${config.systemd.package}/bin/systemd-nspawn \
-M "$INSTANCE" -D "/var/lib/containers/$INSTANCE" $extraFlags \
--bind-ro=/nix/store \
--bind-ro=/nix/var/nix/db \
--bind-ro=/nix/var/nix/daemon-socket \
--bind="/nix/var/nix/profiles/per-container/$INSTANCE:/nix/var/nix/profiles" \
--bind="/nix/var/nix/gcroots/per-container/$INSTANCE:/nix/var/nix/gcroots" \
"$SYSTEM_PATH/init"
'';
serviceConfig.ExecStart =
(optionalString cfg.privateNetwork "${runInNetns}/bin/run-in-netns ${ns} ")
+ "${config.systemd.package}/bin/systemd-nspawn"
+ (optionalString cfg.privateNetwork " --capability=CAP_NET_ADMIN")
+ " -M ${name} -D ${cfg.root}"
+ " --bind-ro=/nix/store --bind-ro=/nix/var/nix/db --bind-ro=/nix/var/nix/daemon-socket"
+ " --bind=/nix/var/nix/profiles/per-container/${name}:/nix/var/nix/profiles"
+ " --bind=/nix/var/nix/gcroots/per-container/${name}:/nix/var/nix/gcroots"
+ " ${cfg.path}/init";
preStop =
''
pid="$(cat /sys/fs/cgroup/systemd/machine/${name}.nspawn/system/tasks 2> /dev/null)"
pid="$(cat /sys/fs/cgroup/systemd/machine/$INSTANCE.nspawn/system/tasks 2> /dev/null)"
if [ -n "$pid" ]; then
# Send the RTMIN+3 signal, which causes the container
# systemd to start halt.target.
@ -240,13 +227,38 @@ in
fi
'';
reloadIfChanged = true;
restartIfChanged = false;
#reloadIfChanged = true; # FIXME
serviceConfig.ExecReload =
"${pkgs.bash}/bin/bash -c '"
+ "echo ${cfg.path}/bin/switch-to-configuration test "
+ "| ${pkgs.socat}/bin/socat unix:${cfg.root}/var/lib/root-shell.socket -'";
serviceConfig.ExecReload = pkgs.writeScript "reload-container"
''
#! ${pkgs.stdenv.shell} -e
SYSTEM_PATH=/nix/var/nix/profiles/system
if [ -f "/etc/containers/$INSTANCE.conf" ]; then
. "/etc/containers/$INSTANCE.conf"
fi
echo $SYSTEM_PATH/bin/switch-to-configuration test | \
${pkgs.socat}/bin/socat unix:/var/lib/containers/$INSTANCE/var/lib/root-shell.socket -
'';
};
# 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;
# Generate /etc/hosts entries for the containers.
@ -257,5 +269,7 @@ in
environment.systemPackages = optional (config.containers != {}) nixos-container;
system.build.foo = nixos-container;
};
}

View file

@ -1,15 +1,21 @@
#! @bash@/bin/sh -e
usage() {
echo "Usage: $0 login <container-name>" >&2
echo "Usage: $0 create <container-name> [--config <filename>]" >&2
echo " $0 update <container-name>" >&2
echo " $0 destroy <container-name>" >&2
echo " $0 login <container-name>" >&2
echo " $0 root-shell <container-name>" >&2
echo " $0 set-root-password <container-name> <password>" >&2
}
args="`getopt --options '' -l help -- "$@"`"
args="`getopt --options '' -l help -l config: -- "$@"`"
eval "set -- $args"
extraConfigFile=
while [ $# -gt 0 ]; do
case "$1" in
(--help) usage; exit 0;;
(--config) shift; extraConfigFile=$1;;
(--) shift; break;;
(*) break;;
esac
@ -28,26 +34,104 @@ getContainerRoot() {
fi
}
if [ $action = login ]; then
container="$1"
if [ -z "$container" ]; then usage; exit 1; fi
shift
container="$1"
if [ -z "$container" ]; then usage; exit 1; fi
shift
if [ $action = create ]; then
confFile="/etc/containers/$container.conf"
root="/var/lib/containers/$container"
if [ -e "$confFile" -o -e "$root/nix" ]; then
echo "$0: container $container already exists" >&2
exit 1
fi
profileDir="/nix/var/nix/profiles/per-container/$container"
mkdir -m 0755 -p "$root/etc/nixos" "$profileDir"
config="
{ config, pkgs, ... }:
with pkgs.lib;
{ boot.isContainer = true;
security.initialRootPassword = mkDefault \"!\";
networking.hostName = mkDefault \"$container\";
networking.useDHCP = false;
imports = [ <nixpkgs/nixos/modules/virtualisation/container-login.nix> $extraConfigFile ];
}"
configFile="$root/etc/nixos/configuration.nix"
echo "$config" > "$configFile"
nix-env -p "$profileDir/system" -I "nixos-config=$configFile" -f '<nixpkgs/nixos>' --set -A system
# Allocate a new /8 network in the 10.233.* range.
network="$(sed -e 's/.*_ADDRESS=10\.233\.\(.*\)\..*/\1/; t; d' /etc/containers/*.conf | sort -n | tail -n1)"
if [ -z "$network" ]; then network=0; else : $((network++)); fi
hostAddress="10.233.$network.1"
localAddress="10.233.$network.2"
echo "host IP is $hostAddress, container IP is $localAddress" >&2
cat > "$confFile" <<EOF
PRIVATE_NETWORK=1
HOST_ADDRESS=$hostAddress
LOCAL_ADDRESS=$localAddress
EOF
echo "starting container@$container.service..." >&2
systemctl start "container@$container.service"
elif [ $action = update ]; then
getContainerRoot
configFile="$root/etc/nixos/configuration.nix"
profileDir="/nix/var/nix/profiles/per-container/$container"
nix-env -p "$profileDir/system" -I "nixos-config=$configFile" -f '<nixpkgs/nixos>' --set -A system
echo "reloading container@$container.service..." >&2
systemctl reload "container@$container.service"
elif [ $action = destroy ]; then
getContainerRoot
confFile="/etc/containers/$container.conf"
if [ ! -w "$confFile" ]; then
echo "$0: cannot destroy declarative container (remove it from your configuration.nix instead)"
exit 1
fi
if systemctl show "container@$container.service" | grep -q ActiveState=active; then
echo "stopping container@$container.service..." >&2
systemctl stop "container@$container.service"
fi
rm -f "$confFile"
elif [ $action = login ]; then
getContainerRoot
exec @socat@/bin/socat "unix:$root/var/lib/login.socket" -,echo=0,raw
elif [ $action = root-shell ]; then
container="$1"
if [ -z "$container" ]; then usage; exit 1; fi
shift
getContainerRoot
exec @socat@/bin/socat "unix:$root/var/lib/root-shell.socket" -
elif [ $action = set-root-password ]; then
password="$1"
if [ -z "$password" ]; then usage; exit 1; fi
# FIXME: not very secure.
getContainerRoot
(echo "passwd"; echo "$password"; echo "$password") | @socat@/bin/socat "unix:$root/var/lib/root-shell.socket" -
else
echo "$0: unknown action $action" >&2
exit 1