gluster volfile parser / extractor

glusterconf.rb

#!/usr/bin/env ruby

module GlusterConf
extend self

  class GlusterConfError < Exception
  end

  def assert x, *bool
    bool.each { |b| raise GlusterConfError, "#{$.}: #{x}" unless bool }
  end

  LOGSEP = /\A\+---/
  IDP = proc {|x| x}

  # extract conf from logs
  def preparse src
    vols = []
    in_vol = nil
    is_log = nil
    preprocess = nil
    src.each { |l|
      (preprocess || IDP)[l] =~ /\A\s*\Z/ and next
      if in_vol
        if is_log and l =~ LOGSEP
          in_vol = false
        else
          vols.last << preprocess[l]
        end
      else
        if l =~ /\A\s*(volume|type|option|subvolumes|end-volume)(\s|\Z)/
          in_vol == false and raise "mixed source"
          in_vol = true
          preprocess = IDP
          is_log = false
          vols << [l]
        else
          is_log = true
          preprocess ||= proc { |x| x.sub /\A\s*\d+: /, "" }
          if l =~ LOGSEP
            in_vol = true
            vols << []
          end
        end
      end
    }

    vols
  end

  def parse src
    volh = {}
    vol = {}

    src.each { |l|
      ls = l.split
      case ls[0]
      when "volume"
        assert l, ls.size == 2, vol.empty?
        vol["name"] = ls[1]
      when "type"
        assert l, ls.size == 2, vol["name"], !vol["type"]
        vol["type"] = ls[1]
      when "option"
        assert l, ls.size == 3, vol["name"]
        (vol["option"] ||= {})[ls[1]] = case ls[2]
        when /\A\d+\Z/
          Integer ls[2]
        when /\Aon|yes|true|enable\Z/i
          true
        when /\Aoff|no|false|disable\Z/i
          false
        else
          ls[2]
        end
      when "subvolumes"
        assert l, ls.size > 1, vol["name"], !vol["subvolumes"]
        vol["subvolumes"] = ls[1..-1]
      when "end-volume"
        assert l, ls.size == 1, vol["name"], vol["type"]
        volh[vol["name"]] = vol
        vol = {}
      when nil
      else
        assert l, false
      end
    }

    # XXX we could have more proper check to see if graph is a tree
    subvolumes = []
    volh.each_value { |vol| subvolumes.concat(vol["subvolumes"] || []) }
    topvols = volh.keys - subvolumes
    assert "ambiguous toplevel volume: #{topvols.join(", ")}", topvols.size == 1
    topvol = volh[topvols[0]]

    volh.each_value { |vol| (vol["subvolumes"] || []).map! { |w| volh.fetch w } }

    topvol
  end

end

if __FILE__ == $0
  require 'yaml'

  $*.each { |f|
    GlusterConf.module_eval {
      preparse(f == "-" ? STDIN : IO.readlines(f)).each { |v|
        print parse(v).to_yaml
      }
    }
  }
end