Modifying the OpenStack configuration

It would be ludicrous to think that all of the playbooks would be needed to run again for a small change such as changing the CPU contention ratio from 4:1 to 8:1. So instead, the playbooks have been developed and tagged so that specific playbooks can be run associated with that particular project that would reconfigure and restart the associated services to pick up the changes.

Getting ready

Ensure that you are root on the deployment host. In most cases, this is the first infrastructure controller node, infra01.

How to do it...

The following are the common changes and how they can be changed using Ansible. As we'll adjust the configuration, all of these commands are executed from the same host you used to perform the installation.

To adjust the CPU overcommit/allocation ratio, carry out the following steps:

1. Edit the /etc/openstack_deploy/user_variables.yml file and modify (or add) the following line (adjust the figure to suit):

   nova_cpu_allocation_ratio: 8.0
   

2. Now execute the following commands to make changes in the environment:

   cd /opt/openstack-ansible/playbooks
   openstack-ansible os-nova-install.yml --tags 'nova-config'
   

For more complex changes, for example, to add configuration that isn't a simple one-line change in a template, we can use an alternative in the form of overrides. To make changes to the default Nova Quotas, carry out the following as an example:

1. Edit the /etc/openstack_deploy/user_variables.yml file and modify (or add) the following line (adjust the figure to suit):

   nova_nova_conf_overrides:  
     DEFAULT:
      quota_fixed_ips = -1
      quota_floating_ips = 20
      quota_instances = 20

2. Now execute the following commands to make changes in the environment:

   cd /opt/openstack-ansible/playbooks
   openstack-ansible os-nova-install.yml --tag 'nova-config'
   

Changes for Neutron, Glance, Cinder, and all other services are modified in a similar way. Adjust the name of the service in the syntax used. For example, to change a configuration item in the neutron.conf file, you would use the following syntax:

neutron_neutron_conf_overrides:  
  DEFAULT:
   dhcp_lease_duration = -1

Then execute the following commands:

cd /opt/openstack-ansible/playbooks
openstack-ansible os-neutron-install.yml --tag 'neutron-config'

How it works…

We modified the same OpenStack-Ansible configuration files as in the Configuring the installation recipe and executed the openstack-ansible playbook command, specifying the playbook that corresponded to the service we wanted to change. As we were making configuration changes, we notified Ansible of this through the --tag parameter.

Refer to https://docs.openstack.org/ for all configuration options for each service.