Module: ZTK::SSH::Exec

Included in:
ZTK::SSH
Defined in:
lib/ztk/ssh/exec.rb

Overview

SSH Command Execution Functionality

Instance Method Summary (collapse)

Instance Method Details

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

Executes a command on the remote host.

Examples:

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

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.

  • (OpenStruct#exit) —

    The exit status (i.e. $?).



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# 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