Module: ZTK::Command::Exec

Included in:
ZTK::Command
Defined in:
lib/ztk/command/exec.rb

Overview

Command Exec Functionality

Instance Method Summary (collapse)

Instance Method Details

- (OpenStruct#output, OpenStruct#exit_code) exec(command, options = {})

Execute Command

Examples:

Execute a command:

cmd = ZTK::Command.new(:silence => true)
puts cmd.exec("hostname", :silence => false).inspect

Parameters:

  • command (String) —

    The command to execute.

  • options (Hash) (defaults to: {}) —

    The options hash for executing the command.

Options Hash (options):

  • :timeout (Integer) — default: 600 —

    How long in seconds before the command will timeout.

  • :ignore_exit_status (Boolean) — default: false —

    Whether or not we should ignore the exit status of the the process we spawn. By default we do not ignore the exit status and throw an exception if it is non-zero.

  • :exit_code (Integer) — default: 0 —

    The exit code we expect the process to return. This is ignore if ignore_exit_status is true.

  • :silence (Boolean) — default: false —

    Whether or not we should squelch the output of the process. The output will always go to the logging device supplied in the ZTK::UI object. The output is always available in the return value from the method additionally.

Returns:

  • (OpenStruct#output) —

    The output of the command, both STDOUT and STDERR combined.

  • (OpenStruct#exit_code) —

    The exit code of the process.



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# File 'lib/ztk/command/exec.rb', line 31

def exec(command, options={})
  options = OpenStruct.new(config.send(:table).merge(options))

  options.ui.logger.debug { "config=#{options.send(:table).inspect}" }
  options.ui.logger.debug { "options=#{options.send(:table).inspect}" }
  options.ui.logger.info { "command(#{command.inspect})" }

  if options.replace_current_process
    options.ui.logger.fatal { "REPLACING CURRENT PROCESS - GOODBYE!" }
    Kernel.exec(command)
  end

  output = ""
  exit_code = -1
  stdout_header = false
  stderr_header = false

  parent_stdout_reader, child_stdout_writer = IO.pipe
  parent_stderr_reader, child_stderr_writer = IO.pipe

  start_time = Time.now.utc

  pid = Process.fork do
    parent_stdout_reader.close
    parent_stderr_reader.close

    STDOUT.reopen(child_stdout_writer)
    STDERR.reopen(child_stderr_writer)
    STDIN.reopen("/dev/null")

    child_stdout_writer.close
    child_stderr_writer.close

    Kernel.exec(command)
  end
  child_stdout_writer.close
  child_stderr_writer.close

  reader_writer_key = {parent_stdout_reader => :stdout, parent_stderr_reader => :stderr}
  reader_writer_map = {parent_stdout_reader => options.ui.stdout, parent_stderr_reader => options.ui.stderr}

  direct_log(:info) { log_header("COMMAND") }
  direct_log(:info) { "#{command.inspect}\n" }
  direct_log(:info) { log_header("STARTED", "-") }

  begin
    Timeout.timeout(options.timeout) do
      loop do
        read_pipes, error_pipes = IO.select(reader_writer_map.keys, [], reader_writer_map.keys, 1)
        [read_pipes].flatten.compact.each do |pipe|
          data = nil
          begin
            data = pipe.read_nonblock(4096)
          rescue Errno::EWOULDBLOCK, Errno::EAGAIN, EOFError => e
            config.ui.logger.debug { e.inspect }
          end

          if (data.nil? || data.empty?)
            next
          end

          case reader_writer_key[pipe]
          when :stdout then
            if !stdout_header
              direct_log(:info) { log_header("STDOUT", "-") }
              stdout_header = true
              stderr_header = false
            end
            reader_writer_map[pipe].write(data) unless options.silence
            direct_log(:info) { data }

          when :stderr then
            if !stderr_header
              direct_log(:warn) { log_header("STDERR", "-") }
              stderr_header = true
              stdout_header = false
            end
            reader_writer_map[pipe].write(data) unless options.silence
            direct_log(:warn) { data }
          end

          output += data

          options.on_progress.nil? or options.on_progress.call
        end

        if !(Process.waitpid(pid, Process::WNOHANG) rescue nil).nil?
          break
        end
      end

    end
  rescue Timeout::Error => e
    direct_log(:fatal) { log_header("TIMEOUT") }
    log_and_raise(CommandError, "Process timed out after #{options.timeout} seconds!")
  end

  exit_code = $?.exitstatus
  direct_log(:info) { log_header("STOPPED") }

  parent_stdout_reader.close
  parent_stderr_reader.close

  options.ui.logger.debug { "exit_code(#{exit_code})" }

  if !options.ignore_exit_status && (exit_code != options.exit_code)
    log_and_raise(CommandError, "exec(#{command.inspect}, #{options.inspect}) failed! [#{exit_code}]")
  end
  OpenStruct.new(:command => command, :output => output, :exit_code => exit_code)
end