stockholm/krebs/3modules/sync-containers3.nix

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{ config, lib, pkgs, ... }: let
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cfg = config.krebs.sync-containers3;
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slib = pkgs.stockholm.lib;
in {
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options.krebs.sync-containers3 = {
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inContainer = {
enable = lib.mkEnableOption "container config for syncing";
pubkey = lib.mkOption {
type = lib.types.str; # TODO ssh key
};
};
containers = lib.mkOption {
default = {};
type = lib.types.attrsOf (lib.types.submodule ({ config, ... }: {
options = {
name = lib.mkOption {
type = lib.types.str;
default = config._module.args.name;
};
sshKey = lib.mkOption {
type = slib.types.absolute-pathname;
};
luksKey = lib.mkOption {
type = slib.types.absolute-pathname;
default = config.sshKey;
};
ephemeral = lib.mkOption {
type = lib.types.bool;
default = false;
};
runContainer = lib.mkOption {
type = lib.types.bool;
default = true;
};
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};
}));
};
};
config = lib.mkMerge [
(lib.mkIf (cfg.containers != {}) {
containers = lib.mapAttrs' (n: ctr: lib.nameValuePair ctr.name {
config = {
environment.systemPackages = [
pkgs.dhcpcd
pkgs.git
pkgs.jq
];
networking.useDHCP = lib.mkForce true;
systemd.services.autoswitch = {
environment = {
NIX_REMOTE = "daemon";
};
wantedBy = [ "multi-user.target" ];
serviceConfig.ExecStart = pkgs.writers.writeDash "autoswitch" ''
set -efu
mkdir -p /var/state/var_src
ln -Tfrs /var/state/var_src /var/src
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if test -e /var/src/nixos-config; then
/run/current-system/sw/bin/nixos-rebuild -I /var/src switch || :
fi
'';
unitConfig.X-StopOnRemoval = false;
};
};
autoStart = false;
enableTun = true;
ephemeral = ctr.ephemeral;
privateNetwork = true;
hostBridge = "ctr0";
bindMounts = {
"/var/lib/self/disk" = {
hostPath = "/var/lib/sync-containers3/${ctr.name}/disk";
isReadOnly = false;
};
"/var/state" = {
hostPath = "/var/lib/sync-containers3/${ctr.name}/state";
isReadOnly = false;
};
};
}) (lib.filterAttrs (_: ctr: ctr.runContainer) cfg.containers);
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systemd.services = lib.foldr lib.recursiveUpdate {} (lib.flatten (map (ctr: [
{ "${ctr.name}_syncer" = {
path = with pkgs; [
coreutils
consul
rsync
openssh
systemd
];
startAt = "*:0/1";
serviceConfig = {
User = "${ctr.name}_container";
LoadCredential = [
"ssh_key:${ctr.sshKey}"
];
ExecCondition = pkgs.writers.writeDash "${ctr.name}_checker" ''
set -efu
! systemctl is-active --quiet container@${ctr.name}.service
'';
ExecStart = pkgs.writers.writeDash "${ctr.name}_syncer" ''
set -efux
consul lock sync_${ctr.name} ${pkgs.writers.writeDash "${ctr.name}-sync" ''
set -efux
if /run/wrappers/bin/ping -c 1 ${ctr.name}.r; then
nice --adjustment=30 rsync -a -e "ssh -i $CREDENTIALS_DIRECTORY/ssh_key" --timeout=30 --inplace --sparse container_sync@${ctr.name}.r:disk "$HOME"/disk.rsync
touch "$HOME"/incomplete
nice --adjustment=30 rsync --inplace "$HOME"/disk.rsync "$HOME"/disk
rm -f "$HOME"/incomplete
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fi
''}
'';
};
}; }
{ "${ctr.name}_watcher" = lib.mkIf ctr.runContainer {
path = with pkgs; [
coreutils
consul
cryptsetup
curl
mount
util-linux
jq
retry
];
serviceConfig = {
ExecStart = pkgs.writers.writeDash "${ctr.name}_watcher" ''
set -efux
while sleep 5; do
# get the payload
# check if the host reacted recently
case $(curl -s -o /dev/null --retry 10 --retry-delay 10 -w '%{http_code}' http://127.0.0.1:8500/v1/kv/containers/${ctr.name}) in
404)
echo 'got 404 from kv, should kill the container'
break
;;
500)
echo 'got 500 from kv, will kill container'
break
;;
200)
# echo 'got 200 from kv, will check payload'
payload=$(consul kv get containers/${ctr.name}) || continue
export payload
if [ "$(jq -rn 'env.payload | fromjson.host')" = '${config.networking.hostName}' ]; then
# echo 'we are the host, trying to reach container'
if $(retry -t 10 -d 10 -- /run/wrappers/bin/ping -q -c 1 ${ctr.name}.r > /dev/null); then
# echo 'container is reachable, continueing'
continue
else
# echo 'container seems dead, killing'
break
fi
else
echo 'we are not host, killing container'
break
fi
;;
*)
echo 'unknown state, continuing'
continue
;;
esac
done
/run/current-system/sw/bin/nixos-container stop ${ctr.name} || :
umount /var/lib/sync-containers3/${ctr.name}/state || :
cryptsetup luksClose ${ctr.name} || :
'';
};
}; }
{ "${ctr.name}_scheduler" = lib.mkIf ctr.runContainer {
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wantedBy = [ "multi-user.target" ];
path = with pkgs; [
coreutils
consul
cryptsetup
mount
util-linux
curl
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systemd
jq
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retry
bc
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];
serviceConfig = {
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Restart = "always";
RestartSec = "30s";
ExecStart = pkgs.writers.writeDash "${ctr.name}_scheduler" ''
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set -efux
# get the payload
# check if the host reacted recently
case $(curl -s -o /dev/null --retry 10 -w '%{http_code}' http://127.0.0.1:8500/v1/kv/containers/${ctr.name}) in
404)
# echo 'got 404 from kv, will create container'
;;
500)
# echo 'got 500 from kv, retrying again'
exit 0
;;
200)
# echo 'got 200 from kv, will check payload'
export payload=$(consul kv get containers/${ctr.name})
if [ "$(jq -rn 'env.payload | fromjson.host')" = '${config.networking.hostName}' ]; then
echo 'we are the host, starting container'
else
# echo 'we are not host, checking timestamp'
# if [ $(echo "$(date +%s) - $(jq -rn 'env.payload | fromjson.time') > 100" | bc) -eq 1 ]; then
if [ "$(jq -rn 'env.payload | fromjson.time | now - tonumber > 100')" = 'true' ]; then
echo 'last beacon is more than 100s ago, taking over'
else
# echo 'last beacon was recent. trying again'
exit 0
fi
fi
;;
*)
echo 'unknown state, bailing out'
exit 0
;;
esac
consul kv put containers/${ctr.name} "$(jq -cn '{host: "${config.networking.hostName}", time: now}')" >/dev/null
consul lock -verbose -monitor-retry=100 -timeout 30s -name container_${ctr.name} container_${ctr.name} ${pkgs.writers.writeBash "${ctr.name}-start" ''
set -efu
cryptsetup luksOpen --key-file ${ctr.luksKey} /var/lib/sync-containers3/${ctr.name}/disk ${ctr.name} || :
mkdir -p /var/lib/sync-containers3/${ctr.name}/state
mountpoint /var/lib/sync-containers3/${ctr.name}/state || mount /dev/mapper/${ctr.name} /var/lib/sync-containers3/${ctr.name}/state
/run/current-system/sw/bin/nixos-container start ${ctr.name}
# wait for system to become reachable for the first time
systemctl start ${ctr.name}_watcher.service
retry -t 10 -d 10 -- /run/wrappers/bin/ping -q -c 1 ${ctr.name}.r > /dev/null
while systemctl is-active container@${ctr.name}.service >/devnull && /run/wrappers/bin/ping -q -c 3 ${ctr.name}.r >/dev/null; do
consul kv put containers/${ctr.name} "$(jq -cn '{host: "${config.networking.hostName}", time: now}')" >/dev/null
sleep 10
done
''}
'';
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};
}; }
{ "container@${ctr.name}" = lib.mkIf ctr.runContainer {
serviceConfig = {
ExecStop = pkgs.writers.writeDash "remove_interface" ''
${pkgs.iproute2}/bin/ip link del vb-${ctr.name}
'';
};
}; }
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]) (lib.attrValues cfg.containers)));
systemd.timers = lib.mapAttrs' (n: ctr: lib.nameValuePair "${ctr.name}_syncer" {
timerConfig = {
RandomizedDelaySec = 100;
};
}) cfg.containers;
users.groups = lib.mapAttrs' (_: ctr: lib.nameValuePair "${ctr.name}_container" {
}) cfg.containers;
users.users = lib.mapAttrs' (_: ctr: lib.nameValuePair "${ctr.name}_container" ({
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group = "${ctr.name}_container";
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isNormalUser = true;
uid = slib.genid_uint31 "container_${ctr.name}";
home = "/var/lib/sync-containers3/${ctr.name}";
createHome = true;
homeMode = "705";
})) cfg.containers;
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environment.systemPackages = lib.mapAttrsToList (_: ctr: (pkgs.writers.writeDashBin "${ctr.name}_init" ''
set -efux
export PATH=${lib.makeBinPath [
pkgs.coreutils
pkgs.cryptsetup
pkgs.libxfs.bin
]}:$PATH
truncate -s 5G /var/lib/sync-containers3/${ctr.name}/disk
cryptsetup luksFormat /var/lib/sync-containers3/${ctr.name}/disk ${ctr.luksKey}
cryptsetup luksOpen --key-file ${ctr.luksKey} /var/lib/sync-containers3/${ctr.name}/disk ${ctr.name}
mkfs.xfs /dev/mapper/${ctr.name}
mkdir -p /var/lib/sync-containers3/${ctr.name}/state
mountpoint /var/lib/sync-containers3/${ctr.name}/state || mount /dev/mapper/${ctr.name} /var/lib/sync-containers3/${ctr.name}/state
/run/current-system/sw/bin/nixos-container start ${ctr.name}
/run/current-system/sw/bin/nixos-container run ${ctr.name} -- ${pkgs.writeDash "init" ''
mkdir -p /var/state
''}
'')) cfg.containers;
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})
(lib.mkIf (cfg.containers != {}) {
# networking
# needed because otherwise we lose local dns
environment.etc."resolv.conf".source = lib.mkForce "/run/systemd/resolve/resolv.conf";
boot.kernel.sysctl."net.ipv4.ip_forward" = lib.mkForce 1;
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systemd.network.networks.ctr0 = {
name = "ctr0";
address = [
"10.233.0.1/24"
];
networkConfig = {
# IPForward = "yes";
# IPMasquerade = "both";
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ConfigureWithoutCarrier = true;
DHCPServer = "yes";
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};
};
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systemd.network.netdevs.ctr0.netdevConfig = {
Kind = "bridge";
Name = "ctr0";
};
networking.networkmanager.unmanaged = [ "ctr0" ];
krebs.iptables.tables.filter.INPUT.rules = [
{ predicate = "-i ctr0"; target = "ACCEPT"; }
];
krebs.iptables.tables.filter.FORWARD.rules = [
{ predicate = "-i ctr0"; target = "ACCEPT"; }
{ predicate = "-o ctr0"; target = "ACCEPT"; }
];
krebs.iptables.tables.nat.POSTROUTING.rules = [
{ v6 = false; predicate = "-s 10.233.0.0/24"; target = "MASQUERADE"; }
];
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})
(lib.mkIf cfg.inContainer.enable {
users.groups.container_sync = {};
users.users.container_sync = {
group = "container_sync";
uid = slib.genid_uint31 "container_sync";
isNormalUser = true;
home = "/var/lib/self";
createHome = true;
openssh.authorizedKeys.keys = [
cfg.inContainer.pubkey
];
};
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networking.useHostResolvConf = false;
networking.useNetworkd = true;
systemd.network = {
enable = true;
networks.eth0 = {
matchConfig.Name = "eth0";
DHCP = "yes";
dhcpV4Config.UseDNS = true;
};
};
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})
];
}