Creating a virtual grid with libvirt + debian preseeds + puppet + IceGrid

DebianIce

This recipe explain how to build a grid composed by 6 debian virtual machines running IceGrid. Once the setup is done, the whole process may be executed with absolutelly no user interaction. The process takes advantage from libvirt (for virtual machine installation), debian preseds (for unattended installation) and puppet (for configuration management).

The resulting virtual grid is suitable to make tesing and continuous integration for distributed applications (using ZeroC IceGrid in this case).

WARNING: there is pending work in this post.

ingredients

Install next packages:

  • libvirt-bin
  • virtinst
  • icegrid-gui
  • libguestfs-tools
  • guestfish

guestfs

Some scripts need guestfs. This requires a supermin appliance. To build it execute:

# update-guestfs-appliance 

virtual network

We will use the next network definition. Write it in a file named net-grid.xml:

[ net-grid.xml ]

<network>
  <name>grid</name>
  <forward mode='nat'/>
  <bridge name='virbr1' stp='on' delay='0'/>
  <mac address='52:54:00:6F:5E:D8'/>
  <dns>
    <host ip='192.168.1.1'>
      <hostname>node0</hostname>
      <hostname>puppet</hostname>
    </host>
  </dns>
  <ip address='192.168.1.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.1.2' end='192.168.1.254'/>
      <host mac="00:AA:00:00:00:11" name="node1" ip='192.168.1.11'/>
      <host mac="00:AA:00:00:00:12" name="node2" ip='192.168.1.12'/>
      <host mac="00:AA:00:00:00:13" name="node3" ip='192.168.1.13'/>
      <host mac="00:AA:00:00:00:14" name="node4" ip='192.168.1.14'/>
      <host mac="00:AA:00:00:00:15" name="node5" ip='192.168.1.15'/>
      <host mac="00:AA:00:00:00:16" name="node6" ip='192.168.1.16'/>
    </dhcp>
  </ip>
</network>

# virsh net-define net-grid.xml
# virsh net-start grid

node1 instalation

We make a minimal debian installation and then we will make 5 clones. Next script automates the installation process. Remember you need the preseed.cfg file in current directory (the script web-servers it using Python).

[ install.sh ]

#!/bin/bash --
export LIBVIRT_DEFAULT_URI=qemu:///system
 
name=node1
 
virsh destroy $name
virsh undefine $name
 
python -m SimpleHTTPServer 80 &
 
virt-install \
  --debug \
  --name=$name \
  --ram=512 \
  --disk ./$name.img,size=1.2,sparse=true \
  --location=http://babel.esi.uclm.es/debian/dists/testing/main/installer-i386 \
  --network=network=grid,mac=00:AA:00:00:00:11 \
  --extra-args="\
    auto=true priority=critical vga=normal hostname=$name \
    url=http://192.168.122.1/preseed.cfg"

clonning nodes

Once the installation has finished, we can make clones. To build clean clones is required to remove some settings established during installation. Thanks to guestfs it is easy to remove than settings using libguestfs-tools:

# export LIBVIRT_DEFAULT_URI=qemu:///system
# virt-sysprep -d node1 --enable udev-persistent-net

This is a good moment to set the puppet agent execution using cron. To make this just copy a crontab file in the guest fs:

# export LIBVIRT_DEFAULT_URI=qemu:///system
# guestfish --rw -i -d node1 copy-in puppet/puppet /etc/cron.d/

You need the puppet directory.

It is time to clone:

export LIBVIRT_DEFAULT_URI=qemu:///system
for i in $(seq 2 6); do
    virt-clone --original node1 --name node$i --file ./node$i.img --mac 00:AA:00:00:00:1$i
    virt-sysprep -d node$i --enable hostname --hostname node$i
done

The script set the mac address and hostname in the range node2 to node6. Due the network specification, these hosts will get predefined IP addresses.

starting nodes

export LIBVIRT_DEFAULT_URI=qemu:///system
 
for dom in $(virsh list --all --name); do
    virsh start $dom
done

puppetmaster

You need to install puppetmaster in the host machine. The next command configure master to autosign agent certificates. That is obviously not secure, but convenient for our purposes here. As soon as nodes send cert request, master will sign them and then all of them are ready to apply the manifest.

# hostname puppet
# apt-get install puppetmaster
# echo '*' > /etc/puppet/autosign.conf
# service puppetmaster restart

writing the puppet manifest

Our initial manifest is pretty simple. We want to install some packages: ice34-services, psmisc and configure the icegrid-node service. You must copy next file in /etc/puppet/manifests/site.pp

package {'ice34-services':
  ensure => present,
}
 
package {'psmisc':
  ensure => present,
}
 
file {'/etc/icegrid':
  ensure => 'directory',
  mode => 755,
  owner => root,
}
 
file {['/var/icegrid', '/var/icegrid/db']:
  ensure => 'directory',
  mode => 755,
  owner => root,
}
 
file {'/etc/icegrid/node.config':
  mode => 644,
  owner => root,
  content => "
Ice.Default.Locator=IceGrid/Locator -t:tcp -h node0 -p 4061
IceGrid.Node.Name=${hostname}
IceGrid.Node.Data=/var/icegrid/db
IceGrid.Node.Endpoints=tcp
"
}
 
service {'icegridnode':
  provider => 'base',
  ensure => running,
  start => '/usr/bin/icegridnode --Ice.Config=/etc/icegrid/node.config &',
  stop  => 'killall icegridnode',
  status => 'pgrep icegridnode',
  require => Package['ice34-services', 'psmisc']
}

This is very rough manifest, but enough for this case.

IceGrid configuration

You can see in the sites.pp manifest that we are configuring icegrid nodes to connect to the IceGrid Registry in node0. node0 is an alias for the host computer private IP address (see net-grid.xml). The manifest create required directories and files to get icegridnode running. Note this is not the right way to execute the icegridnode service. It should have a init.d script to get easily managed with puppet.

You must execute an IceGrid Registry in the host computer. You will need the file registry.config.

$ icegrid-node --Ice.Config=icegrid/registry.config

Then, you may connect to the registry with:

$ icegrid-gui --Ice.Config=icegrid/locator.config

If all is working fine, you will see the 6 nodes in the “live deployment” tab of icegrid-gui.

references

  • Thanks to magmax for its puppet support.

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If you got lost or the

If you got lost or the installation process failed, the simplest way to write a preseed file is to install a system by hand. Then "debconf-get-selections --installer > file" will provide the answers concerning the installer in the file "file". You will need to install the "debconf-utils" package.