Working with nova-schedulers

When you launch an instance with OpenStack, the job of the nova-schedulers is to determine which Compute Host (hypervisor) the instance will be created on. The scheduler can be configured to make some basic decisions, such as whether or not RAM exists or not to run the instance and whether enough cores are available. It can also be configured to be more complex and make decisions based on environmental factors and metadata, so that instances can be grouped together on hosts or spread across different hosts to ensure a level of stability in the event of a compute host failure.

Getting ready

Ensure that you are logged in to the OpenStack controller node. If you used Vagrant to create this, we can access this with the following command:

vagrant ssh controller

How to do it...

Let’s modify the /etc/nova/nova.conf file to enable all the scheduler filters discussed:

1. Add the following lines to the [Default] section of the /etc/nova/nova.conf file on the Controller:

   scheduler_driver...