summaryrefslogtreecommitdiff
path: root/src/Propellor/Property/Borg.hs
blob: c02c5fb53f6e686815af915e2cb6b87df601d8f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
-- | Maintainer: Félix Sipma <felix+propellor@gueux.org>
--
-- Support for the Borg backup tool <https://github.com/borgbackup>

module Propellor.Property.Borg
	( installed
	, repoExists
	, init
	, restored
	, backup
	, KeepPolicy (..)
	) where

import Propellor.Base hiding (init)
import Prelude hiding (init)
import qualified Propellor.Property.Apt as Apt
import qualified Propellor.Property.Cron as Cron
import Data.List (intercalate)

type BorgParam = String

type BorgRepo = FilePath

installed :: Property DebianLike
installed = withOS desc $ \w o -> case o of
	(Just (System (Debian _ (Stable "jessie")) _)) -> ensureProperty w $
		Apt.installedBackport ["borgbackup"]
	_ -> ensureProperty w $
		Apt.installed ["borgbackup"]
  where
        desc = "installed borgbackup"

repoExists :: BorgRepo -> IO Bool
repoExists repo = boolSystem "borg" [Param "list", File repo]

-- | Inits a new borg repository
init :: BorgRepo -> Property DebianLike
init backupdir = check (not <$> repoExists backupdir) (cmdProperty "borg" initargs)
	`requires` installed
  where
	initargs =
		[ "init"
		, backupdir
		]

-- | Restores a directory from an borg backup.
--
-- Only does anything if the directory does not exist, or exists,
-- but is completely empty.
--
-- The restore is performed atomically; restoring to a temp directory
-- and then moving it to the directory.
restored :: FilePath -> BorgRepo -> Property DebianLike
restored dir backupdir = go `requires` installed
  where
	go :: Property DebianLike
	go = property (dir ++ " restored by borg") $ ifM (liftIO needsRestore)
		( do
			warningMessage $ dir ++ " is empty/missing; restoring from backup ..."
			liftIO restore
		, noChange
		)

	needsRestore = null <$> catchDefaultIO [] (dirContents dir)

	restore = withTmpDirIn (takeDirectory dir) "borg-restore" $ \tmpdir -> do
		ok <- boolSystem "borg" $
			[ Param "extract"
			, Param backupdir
			, Param tmpdir
			]
		let restoreddir = tmpdir ++ "/" ++ dir
		ifM (pure ok <&&> doesDirectoryExist restoreddir)
			( do
				void $ tryIO $ removeDirectory dir
				renameDirectory restoreddir dir
				return MadeChange
			, return FailedChange
			)

-- | Installs a cron job that causes a given directory to be backed
-- up, by running borg with some parameters.
--
-- If the directory does not exist, or exists but is completely empty,
-- this Property will immediately restore it from an existing backup.
--
-- So, this property can be used to deploy a directory of content
-- to a host, while also ensuring any changes made to it get backed up.
-- For example:
--
-- >	& Borg.backup "/srv/git" "root@myserver:/mnt/backup/git.borg" Cron.Daily
-- >		["--exclude=/srv/git/tobeignored"]
-- >		[Borg.KeepDays 7, Borg.KeepWeeks 4, Borg.KeepMonths 6, Borg.KeepYears 1]
--
-- Note that this property does not initialize the backup repository,
-- so that will need to be done once, before-hand.
--
-- Since borg uses a fair amount of system resources, only one borg
-- backup job will be run at a time. Other jobs will wait their turns to
-- run.
backup :: FilePath -> BorgRepo -> Cron.Times -> [BorgParam] -> [KeepPolicy] -> Property DebianLike
backup dir backupdir crontimes extraargs kp = backup' dir backupdir crontimes extraargs kp
	`requires` restored dir backupdir

-- | Does a backup, but does not automatically restore.
backup' :: FilePath -> BorgRepo -> Cron.Times -> [BorgParam] -> [KeepPolicy] -> Property DebianLike
backup' dir backupdir crontimes extraargs kp = cronjob
	`describe` desc
	`requires` installed
  where
	desc = backupdir ++ " borg backup"
	cronjob = Cron.niceJob ("borg_backup" ++ dir) crontimes (User "root") "/" $
		"flock " ++ shellEscape lockfile ++ " sh -c " ++ backupcmd
	lockfile = "/var/lock/propellor-borg.lock"
	backupcmd = intercalate ";" $
		createCommand
		: if null kp then [] else [pruneCommand]
	createCommand = unwords $
		[ "borg"
		, "create"
		, "--stats"
		]
		++ map shellEscape extraargs ++
		[ shellEscape backupdir ++ "::" ++ "$(date --iso-8601=ns --utc)"
		, shellEscape dir
		]
	pruneCommand = unwords $
		[ "borg"
		, "prune"
		, shellEscape backupdir
		]
		++
		map keepParam kp

-- | Constructs an BorgParam that specifies which old backup generations to
-- keep. By default, all generations are kept. However, when this parameter is
-- passed to the `backup` property, they will run borg prune to clean out
-- generations not specified here.
keepParam :: KeepPolicy -> BorgParam
keepParam (KeepHours n) = "--keep-hourly=" ++ val n
keepParam (KeepDays n) = "--keep-daily=" ++ val n
keepParam (KeepWeeks n) = "--keep-daily=" ++ val n
keepParam (KeepMonths n) = "--keep-monthly=" ++ val n
keepParam (KeepYears n) = "--keep-yearly=" ++ val n

-- | Policy for backup generations to keep. For example, KeepDays 30 will
-- keep the latest backup for each day when a backup was made, and keep the
-- last 30 such backups. When multiple KeepPolicies are combined together,
-- backups meeting any policy are kept. See borg's man page for details.
data KeepPolicy
	= KeepHours Int
	| KeepDays Int
	| KeepWeeks Int
	| KeepMonths Int
	| KeepYears Int