Class: Weave::LazyConnection

Inherits:
Object
  • Object
show all
Defined in:
lib/weave.rb

Overview

An SSH connection which isn't established until it's needed.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(host_string) ⇒ LazyConnection

Returns a new instance of LazyConnection.

Parameters:

  • host_string (String) —

    the host of the form user@host



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# File 'lib/weave.rb', line 122

def initialize(host_string)
  @user, @host = self.class.user_and_host(host_string)
  @connection = nil
  @mutex = NilMutex
end

Instance Attribute Details

#host ⇒ Object (readonly)

The hostname for the ssh connection



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# File 'lib/weave.rb', line 119

def host
  @host
end

#user ⇒ Object (readonly)

The username for the ssh connection



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# File 'lib/weave.rb', line 117

def user
  @user
end

Instance Method Details

#disconnect ⇒ Object

Disconnect, if connected.



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# File 'lib/weave.rb', line 225

def disconnect()
  @connection.close if @connection
  @connection = nil
end

#puts(*args) ⇒ Object

A thread-safe wrapper around Kernel.puts.



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# File 'lib/weave.rb', line 129

def puts(*args) @mutex.synchronize { Kernel.puts(*args) } end

#run(command, options = {}) ⇒ Object

Run a command on this connection. This will open a connection if it's not already connected. The way the output is presented is determined by the option :output. The default, :output => :pretty, prints each line of output with the name of the host and whether the output is stderr or stdout. If :output => :raw, then the output will be passed as is directly back to STDERR or STDOUT as appropriate. If :output => :capture, then this method puts the output into the result hash as { :stdout => "...", :stderr => "..." }.

The result of this method is a hash containing either :exit_code (if the command exited normally) or :exit_signal (if the command exited due to a signal). It also has :stdout and :stderr strings, if option[:output] was set to :capture.

If the option :continue_on_failure is set to true, then this method will continue as normal if the command terminated via a signal or with a non-zero exit status. Otherwise (the default), these will cause a Weave::Error to be raised.

Parameters:

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

    the output options

Options Hash (options):

  • :output (Symbol) —

    the output format



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# File 'lib/weave.rb', line 148

def run(command, options = {})
  options[:output] ||= :pretty
  @connection ||= Net::SSH.start(@host, @user)
  result = options[:output] == :capture ? { :stdout => "", :stderr => "" } : {}
  @connection.open_channel do |channel|
    channel.exec(command) do |_, success|
      unless success
        raise Error, "Could not run ssh command: #{command}"
      end

      channel.on_data do |_, data|
        append_or_print_output(result, data, :stdout, options)
      end

      channel.on_extended_data do |_, type, data|
        next unless type == 1
        append_or_print_output(result, data, :stderr, options)
      end

      channel.on_request("exit-status") do |_, data|
        code = data.read_long
        unless code.zero? || options[:continue_on_failure]
          raise Error, "[#{@host}] command finished with exit status #{code}: #{command}"
        end
        result[:exit_code] = code
      end

      channel.on_request("exit-signal") do |_, data|
        signal = data.read_long
        unless options[:continue_on_failure]
          signal_name = Signal.list.invert[signal]
          signal_message = signal_name ? "#{signal} (#{signal_name})" : "#{signal}"
          raise Error, "[#{@host}] command received signal #{signal_message}: #{command}"
        end
        result[:exit_signal] = signal
      end
    end
  end
  @connection.loop(0.05)
  result
end