1 files changed, 140 insertions, 0 deletions
diff --git a/bin/byteback-prune b/bin/byteback-prune
new file mode 100755
index 0000000..d005289
--- /dev/null
+++ b/bin/byteback-prune
@@ -0,0 +1,140 @@
+#!/usr/bin/ruby
+#
+# Program to free up space on the backup-storage volume, by removing
+# backups (whether by age, or importance).
+#
+
+$LOAD_PATH.unshift('/usr/lib/byteback')
+
+require 'trollop'
+require 'byteback'
+require 'sys/filesystem'
+include Byteback
+include Byteback::Log
+include Byteback::Util
+
+opts = Trollop.options do
+  banner "Prune old backup directories to ensure there's enough space"
+
+  opt :minpercent, 'Start prune when disk has less than this %age free',
+      type: :integer,
+      default: 5
+
+  opt :maxpercent, 'Stop prune when disk has more than this %age free',
+      type: :integer,
+      default: 10
+
+  opt :list, 'List backups in pruning order, no other action'
+
+  opt :prune, 'Prune the next backup if necessary'
+
+  opt :prune_force, 'Prune the next backup regardless'
+
+  opt :order, "Order backups by 'age' or 'importance'",
+      type: :string,
+      default: 'importance'
+
+  opt :verbose, 'Show debugging messages'
+end
+
+@order = opts[:order]
+@verbose = opts[:verbose]
+@do_list = opts[:list]
+@do_prune = opts[:prune]
+@do_prune_force = opts[:prune_force]
+@minpercent = opts[:minpercent]
+@maxpercent = opts[:maxpercent]
+
+@do_prune = true if @do_prune_force
+
+fatal('Must specify one of --prune or --list') unless
+  (@do_prune || @do_list) &&
+  !(@do_prune && @do_list)
+
+fatal("Must specify --order as 'age' or 'importance'") unless
+  @order == 'age' || @order == 'importance'
+
+if BackupDirectory.all.empty?
+  fatal('No backup directories found, need to run byteback-snapshot')
+end
+
+lock_out_other_processes('byteback-prune')
+
+@df_history = DiskFreeHistory.new(ENV['HOME'])
+begin
+  @df_history.new_reading!
+rescue Errno::ENOSPC
+  if @do_list
+    warn("Couldn't write disk history file due to lack of space, ignoring")
+  else
+    warn("Couldn't write disk history file due to lack of space, going to --prune-force")
+    @do_prune = @do_prune_force = true
+  end
+rescue => anything_else
+  error("Couldn't record disk history of #{@df_history.mountpoint} in #{@df_history.history_file}, installation problem?")
+  raise
+end
+
+gradient_30m = @df_history.gradient(1800)
+
+# Check whether we should still be pruning
+#
+@free = @df_history.list.last.percent_free
+PRUNING_FLAG = "#{ENV['HOME']}/.byteback.pruning"
+
+if @do_prune_force
+  info('Forcing prune')
+elsif @free <= @minpercent && !File.exist?(PRUNING_FLAG)
+  info("Starting prune #{@free}% -> #{@maxpercent} free")
+  File.write(PRUNING_FLAG, '')
+elsif @free >= @maxpercent && File.exist?(PRUNING_FLAG)
+  info("Stopping prune, reached #{@free}% free")
+  File.unlink(PRUNING_FLAG)
+elsif File.exist?(PRUNING_FLAG)
+  info("Continuing prune #{@free}% -> #{@maxpercent}, gradient = #{gradient_30m}")
+end
+
+debug("Disc free #{@free}%, 30m gradient = #{gradient_30m}")
+
+def snapshots_in_order
+  list = BackupDirectory.all_snapshots
+  if @order == 'importance'
+    Snapshot.sort_by_importance(list)
+  elsif @order == 'age'
+    list.sort.reverse
+  else
+    fail ArgumentError.new("Unknown snapshot sort method #{method}")
+  end
+end
+
+snapshots = snapshots_in_order
+
+if @do_list
+  print "Backups by #{@order}:\n"
+  snapshots.each_with_index do |snapshot, index|
+    print "#{sprintf('% 3d', index)}: #{snapshot.path}\n"
+  end
+end
+
+# Don't do anything if we've not got two hours of readings
+#
+unless @do_prune_force
+  if @df_history.list.last.time - @df_history.list.first.time < 1800
+    warn('Not enough disc space history to make a decision')
+    exit 0
+  end
+end
+
+exit 0 unless
+  (@do_prune && File.exist?(PRUNING_FLAG)) ||
+  @do_prune_force
+
+exit 0 unless @do_prune_force || gradient_30m == 0
+
+if snapshots.empty?
+  error('No snapshots to delete, is there enough disc space?')
+  exit 1
+end
+
+info("Deleting #{snapshots.last.path}")
+log_system("/sbin/btrfs subvolume delete #{snapshots.last.path}")