We assume that there are machines organized like below.

• Admin machine: 1 host
  • The sample code is executed on this machine
• Managed machine: 3 host
  • sunagimo01: 192.168.2.1
  • sunagimo02: 192.168.2.2
  • sunagimo03: 192.168.2.3
    • #all managed machines can be logined as user "bob" whose password is "bar"
    • #Requirements for managed machines are accessibility through SSH and file transfer with SFTP

Here, we perform operations below to all managed machines.

• 1.Installation of some packages
• 2.Editing of configuration file
• 3.Execution of experiment program
  • Transfer /home/taro/scenario.sh on admin machine to managed machines and executes them
    • echo "hostname: Hello svengali!!"
• #each step is executed serial

Code for above operations can be written like below.

#! /bin/ruby

require "rubygems"
require "svengali"

user_name = "bob"
password = "bar"
# use IP addres due to access by sequence number
IPADDR_BASE = CLibIPAddr.new("192.168.2.1")

MACHINE_NUM = 3
nodes = Array.new(MACHINE_NUM)

tmp_ipaddr = IPADDR_BASE.dup()
MACHINE_NUM.times{ |n|
  # FQDN machine name can be also passed
  nodes[n] = Machine.new(tmp_ipaddr)
  nodes[n].set_auth_info(user_name,password)
  # establishes a transport for command execution via SSH
  nodes[n].establish_session() 
  # install package
  # package system used is default one(yum)
  puts nodes[n].install_package("openmpi") 
  tmp_ipaddr.inc!()
}

nodes.each{ |a_node|
    # edit configuration file( sshd_config )
    sshd_conf = a_node.get_config_file("/etc/ssh/sshd_config")
    sshd_conf.replace_col("X11Forwarding yes","X11Forwarding no") 
    sshd_conf.save()
}

# start experiment
nodes.each{ |a_node|
   # bonus
   puts a_node.exec!("uname -a")
   # executes experiment script
   puts a_node.exec_script_on("/home/taro/scenario.sh","","/home/taro")
}

Execution result

$ruby test_svengali.rb
( --- omitted yum outputs --- )


Linux sunagimo01 2.6.32-22-generic #33-Ubuntu SMP Wed Jan 21 10:44:23 EST 2009
sunagimo01: Hello svengali!!
Linux sunagimo02 2.6.32-22-generic #33-Ubuntu SMP Wed Jan 21 10:44:35 EST 2009
sunagimo02: Hello svengali!!
Linux sunagimo03 2.6.32-22-generic #33-Ubuntu SMP Wed Jan 21 10:44:47 EST 2009
sunagimo03: Hello svengali!!

Operation of network configuration can be written like below.

( --- codes same as former sample code are omitted --- )


gateway_addr = CLibIPAddr.new("xxx.xxx.xxx.xxx")
dns_addr = CLibIPAddr.new("xxx.xxx.xxx.xxx")
netmask_addr = CLibIPAddr.new("xxx.xxx.xxx.xxx")

CHANGED_IPADDR_BASE = CLibIPAddr.new("xxx.xxx.xxx.xxx")
tmp_ipaddr = CHANGED_IPADDR_BASE.dup()
nodes.each{ |a_node|
   # set a IP address in sequence
   a_node.config_nw_interface(:ipaddr => tmp_ipaddr , :interface => "eth0", :netmask => netmask_addr, :gateway => gateway_addr, :onboot => "yes")
   a_node.set_resolver(:primary_ip => dns_addr)

   # reload network configuration of each machine
   # returns after 10 seconds ( use timeout due to avoid implementation problem of Machine class around SSH connection)
   a_node.exec!("/sbin/service network restart", 10)
   tmp_ipaddr.inc!()
}

# reestablish connection with using new addresses
tmp_ipaddr = CHANGED_IPADDR_BASE.dup()
nodes_changed = Array.new(MACHINE_NUM)
nodes_changed.each{ |a_node|
 a_node = Machine.new(tmp_ipaddr.to_s)
 a_node.set_auth_info(user_name,password)
 a_node.establish_session()
 tmp_ipaddr.inc!()

 puts a_node.exec!("/sbin/ifconfig eth0")
}