stockholm/krebs/3modules/backup.nix

316 lines
9.4 KiB
Nix
Raw Normal View History

2015-12-28 18:43:31 +00:00
{ config, lib, pkgs, ... }:
with lib;
let
out = {
options.krebs.backup = api;
config = mkIf cfg.enable imp;
};
cfg = config.krebs.backup;
api = {
enable = mkEnableOption "krebs.backup" // { default = true; };
plans = mkOption {
default = {};
type = types.attrsOf (types.submodule ({ config, ... }: {
2015-12-28 18:43:31 +00:00
# TODO enable = mkEnableOption "TODO" // { default = true; };
options = {
method = mkOption {
type = types.enum ["pull" "push"];
};
name = mkOption {
type = types.str;
default = config._module.args.name;
2015-12-28 18:43:31 +00:00
};
src = mkOption {
type = types.krebs.file-location;
};
dst = mkOption {
type = types.krebs.file-location;
};
startAt = mkOption {
default = "hourly";
type = types.str; # TODO systemd.time(7)'s calendar event
2015-12-28 18:43:31 +00:00
};
snapshots = mkOption {
default = {
hourly = { format = "%Y-%m-%dT%H"; retain = 4; };
daily = { format = "%Y-%m-%d"; retain = 7; };
weekly = { format = "%YW%W"; retain = 4; };
monthly = { format = "%Y-%m"; retain = 12; };
yearly = { format = "%Y"; };
};
2015-12-28 18:43:31 +00:00
type = types.attrsOf (types.submodule {
options = {
format = mkOption {
type = types.str; # TODO date's +FORMAT
};
retain = mkOption {
type = types.nullOr types.int;
default = null; # null = retain all snapshots
};
};
});
};
};
}));
};
};
imp = {
users.groups.backup.gid = genid "backup";
users.users = {}
// {
root.openssh.authorizedKeys.keys =
map (plan: plan.dst.host.ssh.pubkey)
(filter isPullSrc (attrValues cfg.plans))
++
map (plan: plan.src.host.ssh.pubkey)
(filter isPushDst (attrValues cfg.plans))
;
}
;
systemd.services =
flip mapAttrs' (filterAttrs (_:isPullDst) cfg.plans) (name: plan: {
name = "backup.${name}.pull";
value = makePullService plan;
})
//
flip mapAttrs' (filterAttrs (_:isPushSrc) cfg.plans) (name: plan: {
name = "backup.${name}.push";
value = makePushService plan;
})
;
};
isPushSrc = plan:
plan.method == "push" &&
plan.src.host.name == config.krebs.build.host.name;
isPullSrc = plan:
plan.method == "pull" &&
plan.src.host.name == config.krebs.build.host.name;
isPushDst = plan:
plan.method == "push" &&
plan.dst.host.name == config.krebs.build.host.name;
isPullDst = plan:
plan.method == "pull" &&
plan.dst.host.name == config.krebs.build.host.name;
# TODO push destination needs this in the dst.user's PATH
service-path = [
pkgs.coreutils
pkgs.gnused
pkgs.openssh
pkgs.rsync
pkgs.utillinux
];
# TODO if there is plan.user, then use its privkey
makePushService = plan: assert isPushSrc plan; {
path = service-path;
serviceConfig = {
ExecStart = push plan;
Type = "oneshot";
};
startAt = plan.startAt;
};
makePullService = plan: assert isPullDst plan; {
path = service-path;
serviceConfig = {
ExecStart = pull plan;
Type = "oneshot";
};
startAt = plan.startAt;
};
push = plan: let
2016-02-07 04:32:03 +00:00
# We use pkgs.writeDashBin and return the absolute path so systemd will
# produce nice names in the log, i.e. without the Nix store hash.
2015-12-28 18:43:31 +00:00
out = "${main}/bin/${main.name}";
2016-02-07 04:32:03 +00:00
main = pkgs.writeDashBin "backup.${plan.name}.push" ''
2015-12-28 18:43:31 +00:00
set -efu
dst=${shell.escape plan.dst.path}
mkdir -m 0700 -p "$dst"
exec flock -n "$dst" ${critical-section}
'';
2016-02-07 04:32:03 +00:00
critical-section = pkgs.writeDash "backup.${plan.name}.push.critical-section" ''
2015-12-28 18:43:31 +00:00
# TODO check if there is a previous
set -efu
identity=${shell.escape plan.src.host.ssh.privkey.path}
src=${shell.escape plan.src.path}
dst_user=root
dst_host=$(${fastest-address plan.dst.host})
dst_port=$(${network-ssh-port plan.dst.host "$dst_host"})
2015-12-28 18:43:31 +00:00
dst_path=${shell.escape plan.dst.path}
dst=$dst_user@$dst_host:$dst_path
2015-12-28 18:43:31 +00:00
# Export NOW so runtime of rsync doesn't influence snapshot naming.
export NOW
NOW=$(date +%s)
echo >&2 "update snapshot: current; $src -> $dst"
rsync >&2 \
-aAXF --delete \
-e "ssh -F /dev/null -i $identity ''${dst_port:+-p $dst_port}" \
2015-12-28 18:43:31 +00:00
--rsync-path ${shell.escape
2016-02-07 05:22:56 +00:00
"mkdir -m 0700 -p ${shell.escape plan.dst.path}/current && rsync"} \
2015-12-28 18:43:31 +00:00
--link-dest="$dst_path/current" \
"$src/" \
"$dst/.partial"
exec ssh -F /dev/null \
-i "$identity" \
''${dst_port:+-p $dst_port} \
"$dst_user@$dst_host" \
2015-12-28 18:43:31 +00:00
-T \
env NOW="$NOW" /bin/sh < ${remote-snapshot}
'';
2016-02-07 04:32:03 +00:00
remote-snapshot = pkgs.writeDash "backup.${plan.name}.push.remote-snapshot" ''
2015-12-28 18:43:31 +00:00
set -efu
dst=${shell.escape plan.dst.path}
if test -e "$dst/current"; then
mv "$dst/current" "$dst/.previous"
fi
mv "$dst/.partial" "$dst/current"
rm -fR "$dst/.previous"
echo >&2
(${(take-snapshots plan).text})
'';
in out;
# TODO admit plan.dst.user and its ssh identity
pull = plan: let
2016-02-07 04:32:03 +00:00
# We use pkgs.writeDashBin and return the absolute path so systemd will
# produce nice names in the log, i.e. without the Nix store hash.
2015-12-28 18:43:31 +00:00
out = "${main}/bin/${main.name}";
2016-02-07 04:32:03 +00:00
main = pkgs.writeDashBin "backup.${plan.name}.pull" ''
2015-12-28 18:43:31 +00:00
set -efu
dst=${shell.escape plan.dst.path}
mkdir -m 0700 -p "$dst"
exec flock -n "$dst" ${critical-section}
'';
2016-02-07 04:32:03 +00:00
critical-section = pkgs.writeDash "backup.${plan.name}.pull.critical-section" ''
2015-12-28 18:43:31 +00:00
# TODO check if there is a previous
set -efu
identity=${shell.escape plan.dst.host.ssh.privkey.path}
src_user=root
src_host=$(${fastest-address plan.src.host})
src_port=$(${network-ssh-port plan.src.host "$src_host"})
src_path=${shell.escape plan.src.path}
src=$src_user@$src_host:$src_path
2015-12-28 18:43:31 +00:00
dst=${shell.escape plan.dst.path}
# Export NOW so runtime of rsync doesn't influence snapshot naming.
export NOW
NOW=$(date +%s)
echo >&2 "update snapshot: current; $dst <- $src"
mkdir -m 0700 -p ${shell.escape plan.dst.path}
rsync >&2 \
-aAXF --delete \
-e "ssh -F /dev/null -i $identity ''${src_port:+-p $src_port}" \
2015-12-28 18:43:31 +00:00
--link-dest="$dst/current" \
"$src/" \
"$dst/.partial"
mv "$dst/current" "$dst/.previous"
mv "$dst/.partial" "$dst/current"
rm -fR "$dst/.previous"
echo >&2
exec ${take-snapshots plan}
'';
in out;
2016-02-07 04:32:03 +00:00
take-snapshots = plan: pkgs.writeDash "backup.${plan.name}.take-snapshots" ''
2015-12-28 18:43:31 +00:00
set -efu
NOW=''${NOW-$(date +%s)}
dst=${shell.escape plan.dst.path}
snapshot() {(
: $ns $format $retain
name=$(date --date="@$NOW" +"$format")
if ! test -e "$dst/$ns/$name"; then
echo >&2 "create snapshot: $ns/$name"
mkdir -m 0700 -p "$dst/$ns"
rsync >&2 \
-aAXF --delete \
--link-dest="$dst/current" \
"$dst/current/" \
"$dst/$ns/.partial.$name"
mv "$dst/$ns/.partial.$name" "$dst/$ns/$name"
echo >&2
fi
case $retain in
([0-9]*)
delete_from=$(($retain + 1))
ls -r "$dst/$ns" \
| sed -n "$delete_from,\$p" \
| while read old_name; do
echo >&2 "delete snapshot: $ns/$old_name"
rm -fR "$dst/$ns/$old_name"
done
;;
(ALL)
:
;;
esac
)}
${concatStringsSep "\n" (mapAttrsToList (ns: { format, retain ? null, ... }:
toString (map shell.escape [
"ns=${ns}"
"format=${format}"
"retain=${if retain == null then "ALL" else toString retain}"
"snapshot"
]))
plan.snapshots)}
'';
# XXX Is one ping enough to determine fastest address?
# Note that we're using net.addrs4 instead of net.aliases because we define
# ports only for addresses. See krebs/3modules/default.nix
fastest-address = host: ''
{ ${pkgs.fping}/bin/fping </dev/null -a \
${concatMapStringsSep " " shell.escape
(mapAttrsToList (_: net: head net.addrs4) host.nets)} \
| ${pkgs.coreutils}/bin/head -1; }
'';
# Note that we don't escape word on purpose, so we deref shell vars.
# TODO type word
network-ssh-port = host: word: ''
case ${word} in
${concatStringsSep ";;\n" (mapAttrsToList
(_: net: "(${head net.addrs4}) echo ${toString net.ssh.port}")
host.nets)};;
esac
'';
2015-12-28 18:43:31 +00:00
in out
2016-01-05 21:57:16 +00:00
# TODO ionice
# TODO mail on failed push, pull
# TODO mail on missing push
# TODO don't cancel plans on activation
# also, don't hang while deploying at:
# starting the following units: backup.wu-home-xu.push.service, backup.wu-home-xu.push.timer
# TODO make sure /bku is properly mounted
# TODO make sure that secure hosts cannot backup to insecure ones
# TODO optionally only backup when src and dst are near enough :)
# TODO try using btrfs for snapshots (configurable)
# TODO warn if partial snapshots are found
# TODO warn if unknown stuff is found in dst path