Net::SSH::Multi is a library for controlling multiple Net::SSH connections via a single interface. It exposes an API similar to that of Net::SSH::Connection::Session and Net::SSH::Connection::Channel, making it simpler to adapt programs designed for single connections to be used with multiple connections.

This library is particularly useful for automating repetitive tasks that must be performed on multiple machines. It executes the commands in parallel, and allows commands to be executed on subsets of servers (defined by groups).

  require 'net/ssh/multi'

  Net::SSH::Multi.start do |session|
    # access servers via a gateway
    session.via 'gateway', 'gateway-user'

    # define the servers we want to use
    session.use 'user1@host1'
    session.use 'user2@host2'

    # define servers in groups for more granular access
    session.group :app do
      session.use 'user@app1'
      session.use 'user@app2'
    end

    # execute commands on all servers
    session.exec "uptime"

    # execute commands on a subset of servers
    session.with(:app).exec "hostname"

    # run the aggregated event loop
    session.loop
  end

See Net::SSH::Multi::Session for more documentation.