Virtual Infrastructure

Virtual Infrastructure:
kvm, uvb + libvirt

Bryan McLellan
http://loftninjas.org
btm@loftninjas.org
Senior Systems Administrator
Widemile

Widemile is awesome

I work there, and thus the world is a better place for all
of humanity.

What I got for “free”

•Identical Blades
•Running non identical Debian installs (etch/sid, i386/amd64)
•Running different versions of vmware-server
• OS, software, installed by hand
• Configure using notes in an outlook public folder
•Host database tracked with DNS
vm04-something.test.widemile.com

Problems

• Lack of Homogeneity

• Monkey configuration sucks

• Documentation offensive

http://www.flickr.com/photos/annebuzz/2666654754/

What I did
• Lack of Homogeneity
– debian pxe install with preseeds
• Monkey configuration sucks
– puppify (configuration management)
– capistrano (ruby scripting over ssh)
– iclassify (node classification)
• Documentation offensive
– Configuration management is self documenting
– Wikify the notes

We can always do better

http://www.flickr.com/photos/jpasden/67513019/

What upset me (nobody else cares)
• PXE installs take soooooo long
• Backporting too many packages to debian
• Interacting with VMware programmatically
too much work.
• VMware UIs cost $$
• Dreams: cpu/ram hotplug, live migration

How I Learned to Stop Worrying and
Love the Bomb
• PXE installs take soooooo long
– deb-bootstrap with ubuntu-vm-builder (2.5min)
• Backporting too many packages to debian
– switch to Ubuntu!
• Interacting with VMware programmatically too much
work.
– libvirt is much easier and cleaner
• VMware UIs cost $$
– Libvirt is free
• Dreams: cpu/ram hotplug, live migration
– Word on the street is that kvm + libvirt support these
– I don’t think they’re there yet though.

libvirt – virtualization API

Started at Redhat ‘s Emerging Technology Group
Was Xen focused, but Redhat recently bought Qumranet, makers of KVM
Ubuntu/Canonical picked KVM as virtualization platform of choice
libvirt doesn’t really support all that
Provides CLI management (virsh)
Provides GUI management (virt-manager)

ubuntu-vm-builder
Bash script wrapper for deb-bootstrap + qemu
apt-get install ubuntu-vm-builder
capistrano script:
vmware: 102 lines
uvb: 12 lines

ubuntu-vm-builder kvm hardy
--addpkg openssh-server
-d /srv/kvm/#{hostname}
--domain #{domain}
--hostname #{hostname}
--mem #{memory}
--mirror http://ubuntu.widemile.com/ubuntu
--libvirt qemu:///system
--bridge #{eth0}

ubuntu-vm-builder
Bash script wrapper for deb-bootstrap + qemu
apt-get install ubuntu-vm-builder
capistrano script:
vmware: 102 lines
uvb: 12 lines
Not a lot of enterprise features yet
ubuntu-vm-builder kvm Bridging vs NAT
hardy
--addpkg openssh-server / creates user
Root password
-d /srv/kvm/#{hostname}
--domain #{domain}
--hostname #{hostname}
--mem #{memory}
--mirror http://ubuntu.widemile.com/ubuntu
--libvirt qemu:///system
--bridge #{eth0}

kvm
The cool hypervisor on the block (ubuntu, redhat)
•
Kernel modifications are mainlined (unlike xen)
•
Super fast / lightweight (feel the wind in your hair)
•
Growing fast
•

class kvm {
case $lsbdistid {
quot;Ubuntuquot;: {
# Only Ubuntu releases are new enough for this

package {
quot;kvmquot;:
ensure => present;
quot;libvirt-binquot;:
ensure => present;
quot;ubuntu-vm-builderquot;:
ensure => latest;
}

file { quot;/srv/kvmquot;:
ensure => directory,
group => admins,
mode => 0775,
}

# Permissions required for remote access
# Puppet doesn't support managing the libvirtd group members through the
group type
file {
quot;/var/run/libvirt/libvirt-sockquot;:
group => admins,
require => Service[quot;libvirt-binquot;];
quot;/var/run/libvirt/libvirt-sock-roquot;:
group => admins,
require => Service[quot;libvirt-binquot;];
}

service { quot;libvirt-binquot;:
ensure => running,
hasstatus => true,
require => Package[quot;libvirt-binquot;],
}

# required by u-v-b
exec { quot;devmapper-autoloadquot;:
command => quot;/bin/echo dm_mod >> /etc/modulesquot;,
onlyif => quot;/usr/bin/test `grep -c '^dm_mod' /etc/modules` -lt 1quot;,
}
exec { quot;devmapper-loadquot;:
command => quot;/sbin/modprobe dm_modquot;,
onlyif => quot;/usr/bin/test `/bin/lsmod | grep -c '^dm_mod'` -lt 1quot;,
}
realize Group[quot;libvirtdquot;]
}
}
}

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