Ruby, net-ssh, running an application on remote systems

ruby-talk
1

ok, I have a server with a dozen systems attached to it. there are
commands that I need to run on each system one at a time. i can
connect to each system with the admin script, i can launch basic
commands i can even launch the script i need to but when that script
tries to launch the partimage application to backup the windows
partitions (this is all being done from linux) it doesn't, i don't get
any good errors it just dies closes the connection an moves onto the
next system.

==admin.rb==
#!/usr/bin/ruby
require 'net/ssh'
Username='root'
Password='{plain_text_password}'
Hosts = (101..112).collect {|x| "192.168.0.#{x}"}
def classroom_pc(host, command)
  Net::SSH.start( host, Username, Password) do |session|
    session.open_channel do |channel|
      channel.on_success do
        puts "Connected to #{host}"
      end
      channel.on_close do
        puts "Connection Closed to #{host}"
      end
      #channel.on_data do |ch, data|
      # puts "\trecieved #{data}"
      # puts "\tfrom #{host}"
      #end

      channel.send_request "shell", nil, true
      channel.send_data "#{command}\n"
      channel.send_data "exit\n"
    end
    session.loop
  end
end
if $0 == __FILE__
        Hosts.length.times do |i|
                classroom_pc(Hosts[i], "/mnt/backup/partimage.rb
save")
        end
end

==/mnt/backup/partimage.rb==
#!/usr/bin/ruby
Win_drive = "/dev/hda1"
Location = "/mnt/backup/classroom/"
File_type = "partimag.gz"
def help_message
        puts "Usage:"
        puts "\tsave to save the image"
        puts "\tload to restore an image"
        puts "\thelp prints this message"
end
def hostname
        `hostname`.chomp
end
def save_image
        system("rm #{Location}#{hostname}*")
        system("partimage -odb -f3 -z1 save #{Win_drive} \
        #{Location}#{hostname}.#{File_type}")
end
def load_image
        system("partimage -eb -f3 restore #{Win_drive} \
        #{Location}#{hostname}.#{File_type}.000")
end

if $0 == __FILE__
        unless ARGV.length == 1
                help_message
        end
        if ARGV.length == 1
                help_message if ARGV[0].downcase == "help"
                save_image if ARGV[0].downcase == "save"
                load_image if ARGV[0].downcase == "load"
        end
end

2

I don't have an answer for your specific question, but you might look into capistrano. It's meant for exactly this, although it runs each request in parallel, not sequentially, which may or may not be a good thing for you...

-philip

···

On Thu, 15 Mar 2007, lance.sanchez@gmail.com wrote:

ok, I have a server with a dozen systems attached to it. there are
commands that I need to run on each system one at a time. i can
connect to each system with the admin script, i can launch basic
commands i can even launch the script i need to but when that script
tries to launch the partimage application to backup the windows
partitions (this is all being done from linux) it doesn't, i don't get
any good errors it just dies closes the connection an moves onto the
next system.

==admin.rb==
#!/usr/bin/ruby
require 'net/ssh'
Username='root'
Password='{plain_text_password}'
Hosts = (101..112).collect {|x| "192.168.0.#{x}"}
def classroom_pc(host, command)
Net::SSH.start( host, Username, Password) do |session|
   session.open_channel do |channel|
     channel.on_success do
       puts "Connected to #{host}"
     end
     channel.on_close do
       puts "Connection Closed to #{host}"
     end
     #channel.on_data do |ch, data|
     # puts "\trecieved #{data}"
     # puts "\tfrom #{host}"
     #end

     channel.send_request "shell", nil, true
     channel.send_data "#{command}\n"
     channel.send_data "exit\n"
   end
   session.loop
end
end
if $0 == __FILE__
       Hosts.length.times do |i|
               classroom_pc(Hosts[i], "/mnt/backup/partimage.rb
save")
       end
end

==/mnt/backup/partimage.rb==
#!/usr/bin/ruby
Win_drive = "/dev/hda1"
Location = "/mnt/backup/classroom/"
File_type = "partimag.gz"
def help_message
       puts "Usage:"
       puts "\tsave to save the image"
       puts "\tload to restore an image"
       puts "\thelp prints this message"
end
def hostname
       `hostname`.chomp
end
def save_image
       system("rm #{Location}#{hostname}*")
       system("partimage -odb -f3 -z1 save #{Win_drive} \
       #{Location}#{hostname}.#{File_type}")
end
def load_image
       system("partimage -eb -f3 restore #{Win_drive} \
       #{Location}#{hostname}.#{File_type}.000")
end

if $0 == __FILE__
       unless ARGV.length == 1
               help_message
       end
       if ARGV.length == 1
               help_message if ARGV[0].downcase == "help"
               save_image if ARGV[0].downcase == "save"
               load_image if ARGV[0].downcase == "load"
       end
end

3

Maybe you would be better off using the net/ssh shell instead of
launching a shell over the channel.
http://net-ssh.rubyforge.org/chapter-5.html

Alternatively you might use channel.exec instead of channel.request
and channel.send_data that do not seem to be the right hammer for this
nail if I recall correctly.
http://net-ssh.rubyforge.org/chapter-4.html

HTH
Robert

···

On 3/14/07, lance.sanchez@gmail.com <lance.sanchez@gmail.com> wrote:

<snip>

--
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw