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Advanced Configuration

Now that you have an idea of where everything is, we can start playing around with configuration and customization. This section will cover some of the common customizations you will want to make to your environment and how to rapidly deploy them.

Configuration of Services​

Kolla Overrides​

One of the more powerful features of Kolla is that enables you to override the out-of-the-box configuration of the services. Kolla will look for files in the /etc/kolla/config directory and use those files to override the default configuration of the services. If the feature or setting has not been integrated into Kolla, but is available upstream, it allows you to immediately consume that new feature by setting the override.

You can set the location of this directory by setting the node_custom_config variable in the globals.yml file. Kolla will then check this directory structure for override files for each service. You can read about this upstream here.

In a nutshell, you specify configuration files and then make the changes to the override file you want to set inside the section you want to override or add to. The directory structure could look something like this:

|-/etc/kolla/config/nova.conf
|-/etc/kolla/config/nova/nova-scheduer.conf
|-/etc/kolla/config/nova/control1/nova.conf
|-/etc/kolla/config/nova/compute1/nova.conf
|-/etc/kolla/config/nova/compute2/nova.conf

This allows you do override per project, per project service , or per project service on a defined host. An example of this might be to set the following on /etc/kolla/config/nova.conf:

[DEFAULT]
resume_guests_state_on_host_boot = true

This change would be merged with the default configuration in Kolla and then deployed out during the next kolla-ansible deploy. As you start to test and tune OpenStack, you will find many various configurations you may want to set and capture so that you can start establishing the configurations of your environment.

tip

As you start to make modifications and overrides to this files, it's important to capture them in a source control system like Git. This will allow you to track the changes you make and also allow you to roll back to a previous configuration if you need to.

Customizing the Deployment​

There are multiple ways of doing this, but one of the best ways I found to make it repeatable and consistent is to leverage Terrafrom to manage the customizations the environment.

Terraform has an OpenStack Provider and it useful for managing things like:

  • Networks
  • Subnets
  • Routers
  • Initial Security Groups
  • Images
  • Flavors

Building containers Customizing configuration files