Bug fixes after testing.

1 files changed, 234 insertions, 234 deletions

diff --git a/byteback-snapshot b/byteback-snapshot
index 4e1be92..c59aa18 100755
--- a/byteback-snapshot
+++ b/byteback-snapshot
@@ -1,234 +1,234 @@
-#!/usr/bin/ruby

-#

-# Program to create a snapshot and/or rotate a directory of backup snapshots 

-# using btrfs subvolume commands.

-

-require 'trollop'

-require 'time'

-

-def error(message)

-	STDERR.print "*** #{message}\n"

-	exit 1

-end

-

-def verbose(message)

-	print "#{Time.now}: #{message}\n" if @verbose

-end

-

-# Icky way to find out free disc space on our mount

-#

-class DiskFree

-	def initialize(mount)

-		@mount = mount

-	end

-

-	def total

-		all[2]

-	end

-

-	def used

-		all[3]

-	end

-

-	def available

-		all[4]

-	end

-

-	def fraction_used

-		disk_device, disk_fs, disk_total, disk_used, disk_available, *rest = all

-		disk_used.to_f / disk_available

-	end

-

-	protected

-

-	def all

-		disk_device, disk_fs, disk_total, disk_used, disk_available, *rest = 

-			df.

-			split("\n")[1].

-			split(/\s+/).

-			map { |i| /^[0-9]+$/.match(i) ? i.to_i : i }

-	end

-

-	def df

-		`/bin/df -T -P -B1 #{@mount}`

-	end

-end

-

-# Represent a directory full of backups where "current"  is a subvolume

-# which is snapshotted to frozen backup directories called e.g. 

-# "yyyy-mm-ddThh:mm".

-#

-class BackupDirectory

-	attr_reader :dir

-

-	def initialize(dir)

-		@dir = Dir.new(dir)

-		current

-	end

-

-	# Return total amount of free space in backup directory (bytes)

-	#

-	def free

-		df = DiskFree.new(@dir.path)

-		df.total - df.used

-	end

-

-	# Return an array of Times representing the current list of 

-	# snapshots.

-	#

-	def snapshot_times

-		@dir.entries.map do |entry|

-			begin

-				Time.parse(entry)

-			rescue ArgumentError => error

-				nil

-			end

-		end.

-		compact.

-		sort

-	end

-

-	# What order to remove snapshots in to regain disk space?

-	#

-	# Order backups by their closeness to defined backup times, which are

-	# listed in a set order (i.e. today's backup is more important than yesterday's).

-	#

-	BACKUP_IMPORTANCE = [0, 1, 2, 3, 7, 14, 21, 28, 56, 112]

-	def snapshot_times_by_importance

-		now = Time.now

-		snapshot_times_unsorted = snapshot_times

-		snapshot_times_sorted = []

-		while !snapshot_times_unsorted.empty?

-			BACKUP_IMPORTANCE.each do |days|

-				target_time = now + (days*86400)

-				closest = snapshot_times_unsorted.inject(nil) do |best, time|

-					if best.nil? || (time-target_time).abs < (best-target_time).abs

-						time

-					else

-						best

-					end

-				end

-				break unless closest

-				snapshot_times_sorted << snapshot_times_unsorted.delete(closest)

-			end

-		end

-		snapshot_times_sorted

-	end

-

-	# Returns the size of the given snapshot (runs du, may be slow)

-	#

-	# Would much prefer to take advantage of this feature:

-	#   http://dustymabe.com/2013/09/22/btrfs-how-big-are-my-snapshots/

-	# but it's not currently in Debian/wheezy.

-	#

-	def snapshot_size(time=snapshot_times.latest)

-		`du -s -b #{snapshot_path(time)}`.to_i

-	end

-

-	def average_snapshot_size(number=10)

-		snapshot_times.sort[0..number].inject(0) { |time, total| snapshot_size(time) } / number

-	end

-

-	# Create a new snapshot of 'current'

-	#

-	def new_snapshot!

-		system_no_error("btrfs subvolume snapshot -r #{current.path} #{snapshot_path}")

-	end

-

-	def delete_snapshot!(time)

-		system_no_error("btrfs subvolume delete #{snapshot_path(time)}")

-	end

-

-	def current

-		Dir.new("#{dir.path}/current")

-	end

-

-	def snapshot_path(time=Time.now)

-		"#{dir.path}/#{time.strftime("%Y-%m-%dT%H:%M")}"

-	end

-

-	protected

-

-	def system_no_error(*args)

-		raise RuntimeError.new("Command failed: "+args.join(" ")) unless

-		  system(*args)

-	end

-end

-

-opts = Trollop::options do

-

-    opt :root, "Backups directory (must be a btrfs subvolume)",

-    	:type => :string

-

-    opt :snapshot, "Take a new snapshot"

-

-    opt :prune, "Prune old backups"

-    	:type => :string

-

-    opt :list, "List backups (by 'age' or 'importance')",

-    	:type => :string

-

-    opt :verbose, "Print diagnostics"

-

-end

-

-@root = opts[:root]

-@verbose = opts[:verbose]

-@do_snapshot = opts[:snapshot]

-@do_list = opts[:list]

-@do_prune = opts[:prune]

-

-error("Must specify snapshot, prune or list") unless @do_snapshot || @do_prune || @do_list

-

-error("--root not readable") unless File.directory?(@root)

-

-@backups = BackupDirectory.new(@root)

-

-def get_snapshots_by(method)

-	if method == 'importance'

-		@backups.snapshot_times_by_importance.reverse # least important first

-	elsif method == 'age'

-		@backups.snapshot_times

-	else

-		raise ArgumentError.new("Unknown snapshot sort method #{method}")

-	end

-end

-

-if @do_snapshot

-	last_snapshot_time = @backups.snapshots.last

-	error("Last snapshot was less than six hours ago") unless 

-		!last_snapshot_time || 

-		Time.now - @backups.snapshots.last >= 6*60*60 # FIXME: make configurable

-

-	verbose "Making new snapshot"

-	@backups.new_snapshot! 

-end

-

-if @do_list

-	list = get_snapshots_by(@do_list)

-	print "Backups in #{@root} by #{@do_list}:\n"

-	list.each_with_index do |time, index|

-		print "#{sprintf('% 3d',index)}: #{time}\n"

-	end

-end

-

-if @do_prune

-	verbose "Counting last 10 backups"

-	target_free_space = 1.5 * @backups.average_snapshot_size(10)

-	verbose "Want to ensure we have #{target_free_space}"

-

-	if @backups.free >= target_free_space

-		verbose "(we have #{@backups.free} so no action needed)"

-	else

-		list = get_snapshots_by(@do_prune)

-

-		while @backups.free < target_free_space && !list.empty?

-			to_delete = list.pop

-			verbose "Deleting #{to_delete}"

-			@backups.delete_snapshot!(to_delete)

-			verbose "Leaves us with #{@backups.free}"

-		end

-	end

-end

-

-verbose "Finished"

+#!/usr/bin/ruby
+#
+# Program to create a snapshot and/or rotate a directory of backup snapshots 
+# using btrfs subvolume commands.
+
+require 'trollop'
+require 'time'
+
+def error(message)
+	STDERR.print "*** #{message}\n"
+	exit 1
+end
+
+def verbose(message)
+	print "#{Time.now}: #{message}\n" if @verbose
+end
+
+# Icky way to find out free disc space on our mount
+#
+class DiskFree
+	def initialize(mount)
+		@mount = mount
+	end
+
+	def total
+		all[2]
+	end
+
+	def used
+		all[3]
+	end
+
+	def available
+		all[4]
+	end
+
+	def fraction_used
+		disk_device, disk_fs, disk_total, disk_used, disk_available, *rest = all
+		disk_used.to_f / disk_available
+	end
+
+	protected
+
+	def all
+		disk_device, disk_fs, disk_total, disk_used, disk_available, *rest = 
+			df.
+			split("\n")[1].
+			split(/\s+/).
+			map { |i| /^[0-9]+$/.match(i) ? i.to_i : i }
+	end
+
+	def df
+		`/bin/df -T -P -B1 #{@mount}`
+	end
+end
+
+# Represent a directory full of backups where "current"  is a subvolume
+# which is snapshotted to frozen backup directories called e.g. 
+# "yyyy-mm-ddThh:mm".
+#
+class BackupDirectory
+	attr_reader :dir
+
+	def initialize(dir)
+		@dir = Dir.new(dir)
+		current
+	end
+
+	# Return total amount of free space in backup directory (bytes)
+	#
+	def free
+		df = DiskFree.new(@dir.path)
+		df.total - df.used
+	end
+
+	# Return an array of Times representing the current list of 
+	# snapshots.
+	#
+	def snapshot_times
+		@dir.entries.map do |entry|
+			begin
+				Time.parse(entry)
+			rescue ArgumentError => error
+				nil
+			end
+		end.
+		compact.
+		sort
+	end
+
+	# What order to remove snapshots in to regain disk space?
+	#
+	# Order backups by their closeness to defined backup times, which are
+	# listed in a set order (i.e. today's backup is more important than yesterday's).
+	#
+	BACKUP_IMPORTANCE = [0, 1, 2, 3, 7, 14, 21, 28, 56, 112]
+	def snapshot_times_by_importance
+		now = Time.now
+		snapshot_times_unsorted = snapshot_times
+		snapshot_times_sorted = []
+		while !snapshot_times_unsorted.empty?
+			BACKUP_IMPORTANCE.each do |days|
+				target_time = now + (days*86400)
+				closest = snapshot_times_unsorted.inject(nil) do |best, time|
+					if best.nil? || (time-target_time).abs < (best-target_time).abs
+						time
+					else
+						best
+					end
+				end
+				break unless closest
+				snapshot_times_sorted << snapshot_times_unsorted.delete(closest)
+			end
+		end
+		snapshot_times_sorted
+	end
+
+	# Returns the size of the given snapshot (runs du, may be slow)
+	#
+	# Would much prefer to take advantage of this feature:
+	#   http://dustymabe.com/2013/09/22/btrfs-how-big-are-my-snapshots/
+	# but it's not currently in Debian/wheezy.
+	#
+	def snapshot_size(time=snapshot_times.latest)
+		`du -s -b #{snapshot_path(time)}`.to_i
+	end
+
+	def average_snapshot_size(number=10)
+		snapshot_times.sort[0..number].inject(0) { |time, total| snapshot_size(time) } / number
+	end
+
+	# Create a new snapshot of 'current'
+	#
+	def new_snapshot!
+		system_no_error("btrfs subvolume snapshot -r #{current.path} #{snapshot_path}")
+	end
+
+	def delete_snapshot!(time)
+		system_no_error("btrfs subvolume delete #{snapshot_path(time)}")
+	end
+
+	def current
+		Dir.new("#{dir.path}/current")
+	end
+
+	def snapshot_path(time=Time.now)
+		"#{dir.path}/#{time.strftime("%Y-%m-%dT%H:%M")}"
+	end
+
+	protected
+
+	def system_no_error(*args)
+		raise RuntimeError.new("Command failed: "+args.join(" ")) unless
+		  system(*args)
+	end
+end
+
+opts = Trollop::options do
+
+    opt :root, "Backups directory (must be a btrfs subvolume)",
+    	:type => :string
+
+    opt :snapshot, "Take a new snapshot"
+
+    opt :prune, "Prune old backups",
+    	:type => :string
+
+    opt :list, "List backups (by 'age' or 'importance')",
+    	:type => :string
+
+    opt :verbose, "Print diagnostics"
+
+end
+
+@root = opts[:root]
+@verbose = opts[:verbose]
+@do_snapshot = opts[:snapshot]
+@do_list = opts[:list]
+@do_prune = opts[:prune]
+
+error("Must specify snapshot, prune or list") unless @do_snapshot || @do_prune || @do_list
+
+error("--root not readable") unless File.directory?(@root)
+
+@backups = BackupDirectory.new(@root)
+
+def get_snapshots_by(method)
+	if method == 'importance'
+		@backups.snapshot_times_by_importance.reverse # least important first
+	elsif method == 'age'
+		@backups.snapshot_times
+	else
+		raise ArgumentError.new("Unknown snapshot sort method #{method}")
+	end
+end
+
+if @do_snapshot
+	last_snapshot_time = @backups.snapshot_times.last
+	error("Last snapshot was less than six hours ago") unless 
+		!last_snapshot_time || 
+		Time.now - @backups.snapshot_times.last >= 6*60*60 # FIXME: make configurable
+
+	verbose "Making new snapshot"
+	@backups.new_snapshot! 
+end
+
+if @do_list
+	list = get_snapshots_by(@do_list)
+	print "Backups in #{@root} by #{@do_list}:\n"
+	list.each_with_index do |time, index|
+		print "#{sprintf('% 3d',index)}: #{time}\n"
+	end
+end
+
+if @do_prune
+	verbose "Counting last 10 backups"
+	target_free_space = 1.5 * @backups.average_snapshot_size(10)
+	verbose "Want to ensure we have #{target_free_space}"
+
+	if @backups.free >= target_free_space
+		verbose "(we have #{@backups.free} so no action needed)"
+	else
+		list = get_snapshots_by(@do_prune)
+
+		while @backups.free < target_free_space && !list.empty?
+			to_delete = list.pop
+			verbose "Deleting #{to_delete}"
+			@backups.delete_snapshot!(to_delete)
+			verbose "Leaves us with #{@backups.free}"
+		end
+	end
+end
+
+verbose "Finished"