Class: OsCtl::Lib::Exporter::Zfs

Inherits:
Base
  • Object
show all
Includes:
Utils::Log, Utils::System
Defined in:
lib/libosctl/exporter/zfs.rb

Overview

Handles dumping containers as ZFS streams into tar archives

Usage:

exporter.dump_rootfs do
  # Create a snapshot a dump it
  exporter.dump_base

  # Create another snapshot and dump it as an incremental stream
  # from the base snapshot
  exporter.dump_incremental
end

Constant Summary

Constants inherited from Base

Base::BLOCK_SIZE, Base::DIR_MODE, Base::FILE_MODE

Instance Attribute Summary collapse

Attributes inherited from Base

#ct, #datasets, #opts, #tar

Instance Method Summary collapse

Methods included from Utils::System

#find_executable!, #read_process_output, #repeat_on_failure, #syscmd, #syscmd_argv, #write_stdin, #zfs

Methods included from Utils::Log

included

Methods inherited from Base

#add_file_from_disk, #close, #dump_configs, #dump_metadata, #dump_user_hook_scripts

Constructor Details

#initialize(*_) ⇒ Zfs

Returns a new instance of Zfs.



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# File 'lib/libosctl/exporter/zfs.rb', line 20

def initialize(*_)
  super

  @datasets = ct.datasets[1..] # skip the root dataset
  @snapshots = []
end

Instance Attribute Details

#base_snap ⇒ Object (readonly, protected)

Returns the value of attribute base_snap.



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# File 'lib/libosctl/exporter/zfs.rb', line 78

def base_snap
  @base_snap
end

#snapshots ⇒ Object (readonly, protected)

Returns the value of attribute snapshots.



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# File 'lib/libosctl/exporter/zfs.rb', line 78

def snapshots
  @snapshots
end

Instance Method Details

#dump_base ⇒ Object

Dump initial data stream

Should be called from within the block given to #dump_rootfs.



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# File 'lib/libosctl/exporter/zfs.rb', line 53

def dump_base
  @base_snap = snapshot(ct.dataset, 'base')

  each_dataset_file('base') do |ds, file|
    dump_stream(file, ds, base_snap)
  end
end

#dump_file_name(compression, name) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 187

def dump_file_name(compression, name)
  base = File.join('rootfs', "#{name}.dat")

  case compression
  when :gzip
    "#{base}.gz"

  else
    base
  end
end

#dump_incremental(from_snap: nil) ⇒ Object

Dump incremental data stream from the base stream

Should be called from within the block given to #dump_rootfs.



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# File 'lib/libosctl/exporter/zfs.rb', line 64

def dump_incremental(from_snap: nil)
  snap = snapshot(ct.dataset, 'incr')

  each_dataset_file('incremental') do |ds, file|
    dump_stream(file, ds, snap, from_snap || base_snap)
  end
end

#dump_rootfs { ... } ⇒ Object

Method used to wrap dumping of base and incremental data streams of rootfs

Yields:



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# File 'lib/libosctl/exporter/zfs.rb', line 30

def dump_rootfs
  tar.mkdir('rootfs', DIR_MODE)

  each_dataset_dir do |_ds, dir|
    tar.mkdir(File.join('rootfs', dir), DIR_MODE)
  end

  yield

  tar.add_file('snapshots.yml', FILE_MODE) do |tf|
    tf.write(ConfigFile.dump_yaml(snapshots.reverse))
  end
ensure
  each_dataset do |ds|
    snapshots.reverse_each do |snap|
      zfs(:destroy, '', "#{ds}@#{snap}")
    end
  end
end

#dump_stream(name, dataset, snap, from_snap = nil) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 121

def dump_stream(name, dataset, snap, from_snap = nil)
  compression = get_compression(dataset)
  status = nil

  cmd = if from_snap
          "#{zfs_send} -I @#{from_snap} #{dataset}@#{snap}"
        else
          "#{zfs_send} #{dataset}@#{snap}"
        end

  tar.add_file(dump_file_name(compression, name), FILE_MODE) do |tf|
    IO.popen("exec #{cmd}") do |io|
      process_stream(compression, io, tf)
    end

    status = $?
  end

  raise "zfs send failed with exit status #{status.exitstatus}" if status.exitstatus != 0
end

#each_dataset {|ds| ... } ⇒ Object (protected)

Iterate over all datasets

Yield Parameters:



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# File 'lib/libosctl/exporter/zfs.rb', line 82

def each_dataset(&block)
  block.call(ct.dataset)
  datasets.each(&block)
end

#each_dataset_dir {|ds, dir_name| ... } ⇒ Object (protected)

Iterate over all datasets and yield the dataset along with directory name for the tar archive, where its streams will be stored.

Yield Parameters:

  • ds (Zfs::Dataset)
  • dir_name (String) —

    directory name within the archive



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# File 'lib/libosctl/exporter/zfs.rb', line 92

def each_dataset_dir
  each_dataset do |ds|
    yield(ds, ds.relative_name)
  end
end

#each_dataset_file(name) {|ds, fname| ... } ⇒ Object (protected)

Iterate over all datasets and yield the dataset along with file name for the archive.

Parameters:

  • name (String) —

    base/incremental

Yield Parameters:

  • ds (Zfs::Dataset)
  • fname (String) —

    file name within the archive



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# File 'lib/libosctl/exporter/zfs.rb', line 104

def each_dataset_file(name)
  each_dataset_dir do |ds, dir|
    yield(ds, File.join(dir, name))
  end
end

#format ⇒ Object 



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# File 'lib/libosctl/exporter/zfs.rb', line 72

def format
  :zfs
end

#get_compression(dataset) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 173

def get_compression(dataset)
  case opts[:compression]
  when :auto
    if !opts[:compressed_send] || zfs(:get, '-H -o value compression', dataset).output.strip == 'off'
      :gzip
    else
      :off
    end

  else
    opts[:compression].to_sym
  end
end

#process_stream(compression, stream, tf) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 142

def process_stream(compression, stream, tf)
  case compression
  when :gzip
    gz = Zlib::GzipWriter.new(tf)
    attempts = 0

    until stream.eof?
      data = stream.read(BLOCK_SIZE)

      begin
        gz.write(data)
        attempts = 0
      rescue Zlib::BufError
        attempts += 1
        raise if attempts > 5

        sleep(0.1)
        retry
      end
    end

    gz.close

  when :off
    tf.write(stream.read(BLOCK_SIZE)) until stream.eof?

  else
    raise "unexpected compression type '#{compression}'"
  end
end

#snapshot(dataset, type) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 114

def snapshot(dataset, type)
  snap = snapshot_name(type)
  zfs(:snapshot, '-r', "#{dataset}@#{snap}")
  snapshots << snap
  snap
end

#snapshot_name(type) ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 110

def snapshot_name(type)
  "osctl-#{type}-#{Time.now.to_i}"
end

#zfs_send ⇒ Object (protected) 



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# File 'lib/libosctl/exporter/zfs.rb', line 199

def zfs_send
  if opts[:compressed_send]
    'zfs send -c'

  else
    'zfs send'
  end
end