module Net::SSH::Multi::SessionActions

Returns true if any server in the current container has an open SSH session that is currently processing any channels. If include_invisible is false (the default) then invisible channels (such as those created by port forwarding) will not be counted; otherwise, they will be.

# File lib/net/ssh/multi/session_actions.rb, line 29
def busy?(include_invisible=false)
  servers.any? { |server| server.busy?(include_invisible) }
end

Connections are normally established lazily, as soon as they are needed. This method forces all servers in the current container to have their connections established immediately, blocking until the connections have been made.

# File lib/net/ssh/multi/session_actions.rb, line 20
def connect!
  sessions
  self
end

A convenience method for executing a command on multiple hosts and either displaying or capturing the output. It opens a channel on all active sessions (see open_channel and active_sessions), and then executes a command on each channel (Net::SSH::Connection::Channel#exec).

If a block is given, it will be invoked whenever data is received across the channel, with three arguments: the channel object, a symbol identifying which output stream the data was received on (:stdout or :stderr) and a string containing the data that was received:

session.exec("command") do |ch, stream, data|
  puts "[#{ch[:host]} : #{stream}] #{data}"
end

If no block is given, all output will be written to +$stdout+ or +$stderr+, as appropriate.

Note that exec will also capture the exit status of the process in the :exit_status property of each channel. Since exec returns all of the channels in a Net::SSH::Multi::Channel object, you can check for the exit status like this:

channel = session.exec("command") { ... }
channel.wait
if channel.any? { |c| c[:exit_status] != 0 }
  puts "executing failed on at least one host!"
end

# File lib/net/ssh/multi/session_actions.rb, line 119
def exec(command, &block)
  open_channel do |channel|
    channel.exec(command) do |ch, success|
      raise "could not execute command: #{command.inspect} (#{ch[:host]})" unless success

      channel.on_data do |ch, data|
        if block
          block.call(ch, :stdout, data)
        else
          data.chomp.each_line do |line|
            $stdout.puts("[#{ch[:host]}] #{line}")
          end
        end
      end

      channel.on_extended_data do |ch, type, data|
        if block
          block.call(ch, :stderr, data)
        else
          data.chomp.each_line do |line|
            $stderr.puts("[#{ch[:host]}] #{line}")
          end
        end
      end

      channel.on_request("exit-status") do |ch, data|
        ch[:exit_status] = data.read_long
      end
    end
  end
end

Returns the session that is the "master". This defaults to self, but classes that include this module may wish to change this if they are subsessions that depend on a master session.

# File lib/net/ssh/multi/session_actions.rb, line 12
def master
  self
end

Asks all sessions for all contained servers (see sessions) to open a new channel. When each server responds, the on_confirm block will be invoked with a single argument, the channel object for that server. This means that the block will be invoked one time for each session.

All new channels will be collected and returned, aggregated into a new Net::SSH::Multi::Channel instance.

Note that the channels are "enhanced" slightly--they have two properties set on them automatically, to make dealing with them in a multi-session environment slightly easier:

• :server => the Net::SSH::Multi::Server instance that spawned the channel

• :host => the host name of the server

Having access to these things lets you more easily report which host (e.g.) data was received from:

session.open_channel do |channel|
  channel.exec "command" do |ch, success|
    ch.on_data do |ch, data|
      puts "got data #{data} from #{ch[:host]}"
    end
  end
end

# File lib/net/ssh/multi/session_actions.rb, line 80
def open_channel(type="session", *extra, &on_confirm)
  channels = sessions.map do |ssh|
    ssh.open_channel(type, *extra) do |c|
      c[:server] = c.connection[:server]
      c[:host] = c.connection[:server].host
      on_confirm[c] if on_confirm
    end
  end
  Multi::Channel.new(master, channels)
end

Sends a global request to the sessions for all contained servers (see sessions). This can be used to (e.g.) ping the remote servers to prevent them from timing out.

session.send_global_request("keep-alive@openssh.com")

If a block is given, it will be invoked when the server responds, with two arguments: the Net::SSH connection that is responding, and a boolean indicating whether the request succeeded or not.

# File lib/net/ssh/multi/session_actions.rb, line 50
def send_global_request(type, *extra, &callback)
  sessions.each { |ssh| ssh.send_global_request(type, *extra, &callback) }
  self
end

Returns an array of all SSH sessions, blocking until all sessions have connected.

# File lib/net/ssh/multi/session_actions.rb, line 35
def sessions
  threads = servers.map { |server| Thread.new { server.session(true) } if server.session.nil? }
  threads.each { |thread| thread.join if thread }
  servers.map { |server| server.session }.compact
end