capture_ssh.rb

#!/usr/bin/env ruby

require 'pry'


servers = {
  "MAIN_SERVER_1" => "192.168.1.1" # <<-- SERVER IP HERE
}
user = 'user'
command = "tail -F /path/to/log.log | grep 'text here'"



thrs = []
servers.each do |server, ip|
  thrs << Thread.new do
    puts "Starting Monitor for #{server} @ #{ip}"
    call = "ssh #{user}@#{ip} #{command}"
    puts "Making following ssh call: #{call}"


    # This seems to output to STDOUT
    # Comment this out to test the IO capture block below
    system(call)



    # My attempt to wrap this call in a popen call and handle the IO stream with select
    IO.popen(call) do |stream|
      while true
        r, w, e = IO.select([stream], [], [], 1)
        puts "Select fired / timed out"

        # I would expect r (the readable IO array) to have data since stdout has data?
        # But it always ends up returning nil
        p r
        unless r.nil?
          puts r.first.gets
        end

        # If you enable this line, it will drop into the pry shell
        # Oddly, keystrokes seem to be interruped while in this mode...
        # But more interestingly, if I perform a stream.gets I see the line return...?
        # binding.pry
      end
    end

  end
end


thrs.each { |thr| thr.join }