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

[lance.sanchez]

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, "/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

 

[Philip Hallstrom]

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

 

[Robert Dober]

<snip>

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