nodeset-loop

#!/usr/bin/env ruby
#
# Copyright 2015 Victor Penso
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

require 'ostruct'
require 'getoptlong' 
require 'logger'

class System 
  
  def self.exec(command)
    command + ' 2>&1'
    $logger.debug "Exec [#{command}]"
    # Execute command as subprocess and return the exit code
    pipe = IO.popen(command)
    # Get the process ID from the child
    pid = pipe.pid
    # Read the output from the stream
    output = pipe.read
    # Wait for successful return and pass back the code to the caller
    Process.wait(pid)
    state=$?
    $logger.debug "Returned with #{state}"
    if state == 0
      return output
    else
      $logger.warn "Failed to execute [#{command}]"
      return nil
    end
  end

end

exec_name = File.split(__FILE__)[-1]
HELP = <<EOF
Iterate over a nodeset and exectue a command for each node

#{exec_name} [-dhv] COMMAND

  COMMAND
    Command to execute on all nodes "{}" is replaced by the
    node name.

Options
-------

  --debug, -d
    Show stacktraces in case of errors.
  --help, -h
    Show this help information.
  --nodes, -w NODESET
    Nodeset to execute the command on.
  --prefix, -p
    Print node name infront of command output.
  --version, -v
    Print version number.

Environment
-----------

NODES: Nodeset to execute the command on (overwrite with
       options -w).
EOF

begin

  stdin = $stdin.tty? ? String.new : $stdin.read

  options = OpenStruct.new
  options.debug = false
  options.nodeset = String.new
  options.prefix = false
  options.space = false

  $logger = Logger.new($stderr)
  # Adjust the time format used for the logger
  $logger.datetime_format = "%Y-%m-%d %H:%M:%S "
  $logger.formatter = proc do |severity, datetime, progname, message|
    "[#{datetime.strftime($logger.datetime_format)}] #{severity} -- #{message}\n"
  end
  $logger.level = Logger::INFO

  GetoptLong.new(
    ['--debug','-d',GetoptLong::NO_ARGUMENT],
    ['--help','-h',GetoptLong::NO_ARGUMENT],
    ['--log-level','-L',GetoptLong::REQUIRED_ARGUMENT],
    ['--nodes','-w',GetoptLong::REQUIRED_ARGUMENT],
    ['--prefix','-p',GetoptLong::NO_ARGUMENT],
    ['--space','-s',GetoptLong::NO_ARGUMENT],
    ['--version','-v',GetoptLong::NO_ARGUMENT]
  ).each do |opt,arg|
    case opt
    when '--debug'
      options.debug = true
      $logger.level = Logger::DEBUG
    when '--help'
      $stdout.puts HELP
      exit 0
    when '--log-level'
      $logger.level = case arg
      when 'warn'
        Logger::WARN
      when 'debug'
        Logger::DEBUG
      when 'fatal'
        Logger::FATAL
      else
        Logger::INFO
       end
    when '--nodes'
      options.nodeset = arg
    when '--prefix'
      options.prefix = true
    when '--space'
      options.space = true
    when '--version'
      $stdout.puts 0.1
      exit 0
    end
  end

  if options.nodeset.empty?
    if not stdin.empty?
      options.nodeset = stdin
    elsif ENV.has_key? 'NODES'
      options.nodeset = ENV['NODES']
    else
      raise 'No nodeset defined!'
    end
  end

  $logger.debug "Options:\n #{options.inspect}"

  # Expand the nodeset and transform it into an array
  nodeset = `nodeset -e #{options.nodeset}`.split(' ') 

  $logger.debug "Expanded nodeset:\n #{nodeset.inspect}"

  commands = ARGV.join(' ')

  nodeset.each do |node|
    command = commands.gsub(/\{\}/, node)
    $stdout.print "#{node}: " if options.prefix
    $stdout.print "-- #{node} --\n" if options.space
    $stdout.puts System::exec(command)
  end

rescue => exc
  $stderr.puts "ERROR: #{exc.message}"
  $stderr.puts " use -h for detailed instructions"
  if options.debug
    $stderr.puts '-- Stack Trace --'
    $stderr.puts exc.backtrace
  else
    $stderr.puts 'You may want run this in debug mode with \'-d\''
  end
  exit 1
end

exit 0