Event flow when a cloud instance is provisioned in Openstack

Many people think that cloud is alike virtualizastion or other way around. Both technologies have a lot of things in common and with a sophisticated virtualization manager or orchestration tool (example can be a VMware vCenter or vCloud) we get a look and feel that cloud promise but in essence cloud is not the same like virtualization.

In this post instead to polemize who is right or not I would like to rather take a look at the events that are happening when we provision a cloud server, either in cloud or VMware. The inside view is only for the Openstack although.

Problem

What is happening in the Openstack cluster when a cloud server is provisioned and booted.

Solution

Before a VM can be marked as booted and fully provisioned there are number or messages and requests exchanged between the core openstack components[4].

This slides show event after event what is happening: Openstack cloud request flow [2].
This diagram [3] below is an additional visualization of interaction between the components.

References

1. Python Code level analyse
   http://www.laurentluce.com/posts/openstack-nova-internals-of-instance-launching/
2. http://www.slideshare.net/mirantis/openstack-cloud-request-flow
3. Slides on Technical Architecture of Quantum (9/12) from the http://wiki.openstack.org/Quantum
4. http://www.openstack.org/software