module ZTK::SSH::Exec

SSH Command Execution Functionality

Public Instance Methods

exec(command, options={}) click to toggle source

Executes a command on the remote host.

@param [String] command The command to execute. @param [Hash] options The options hash for executing the command. @option options [Integer] :timeout (600) How long in seconds before

the command will timeout.

@option options [Boolean] :ignore_exit_status (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.

@option options [Integer] :exit_code (0) The exit code we expect the

process to return.  This is ignore if *ignore_exit_status* is true.

@option options [Boolean] :silence (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.

@return [OpenStruct#output] The output of the command, both STDOUT and

STDERR.

@return [OpenStruct#exit] The exit status (i.e. $?).

@example Execute a command:

ssh = ZTK::SSH.new
ssh.config do |config|
  config.user = ENV["USER"]
  config.host_name = "127.0.0.1"
end
puts ssh.exec("hostname").inspect
# File lib/ztk/ssh/exec.rb, line 36
def exec(command, options={})
  options = OpenStruct.new(config.send(:table).merge(options))

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

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

  begin
    raise_on_exceptions = [Timeout::Error]
    defined?(Resque) and raise_on_exceptions << Resque::TermException

    ZTK::RescueRetry.try(
      :ui => config.ui,
      :tries => ZTK::SSH::RESCUE_RETRY_ATTEMPTS,
      :raise => raise_on_exceptions,
      :on_retry => method(:on_retry)
    ) do
      Timeout.timeout(options.timeout) do

        channel = ssh.open_channel do |chan|
          options.ui.logger.debug { "Channel opened." }

          (options.request_pty == true) and chan.request_pty do |ch, success|
            if success
              options.ui.logger.debug { "PTY obtained." }
            else
              options.ui.logger.warn { "Could not obtain PTY." }
            end
          end

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

          chan.exec(command) do |ch, success|
            success or log_and_raise(SSHError, "Could not execute '#{command}'.")

            ch.on_data do |c, data|
              if !stdout_header
                direct_log(:info) { log_header("STDOUT", "-") }
                stdout_header = true
                stderr_header = false
              end
              direct_log(:info) { data }

              options.ui.stdout.print(data) unless options.silence
              output += data

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

            ch.on_extended_data do |c, type, data|
              if !stderr_header
                direct_log(:warn) { log_header("STDERR", "-") }
                stderr_header = true
                stdout_header = false
              end
              direct_log(:warn) { data }

              options.ui.stderr.print(data) unless options.silence
              output += data

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

            ch.on_request("exit-status") do |c, data|
              exit_code = data.read_long
            end

            ch.on_request("exit-signal") do |c, data|
              exit_signal = data.read_long
            end

            ch.on_open_failed do |c, code, desc|
              options.ui.logger.fatal { "Open failed! (#{code.inspect} - #{desc.inspect})" }
            end

          end
        end
        channel.wait

        direct_log(:info) { log_header("CLOSED") }
        options.ui.logger.debug { "Channel closed." }
      end
    end

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

  message = [
    "exit_code=#{exit_code}",
    (exit_signal.nil? ? nil : "exit_signal=#{exit_signal} (#{EXIT_SIGNALS[exit_signal]})")
  ].compact.join(", ")

  options.ui.logger.debug { message }

  if !options.ignore_exit_status && (exit_code != options.exit_code)
    log_and_raise(SSHError, message)
  end
  OpenStruct.new(:command => command, :output => output, :exit_code => exit_code, :exit_signal => exit_signal)
end