Octavia flavors are a powerful tool for operators to bring enhanced
load balancing capabilities to their users. An Octavia flavor is a
predefined set of provider configuration options that are created by the
operator. When an user requests a load balancer they can request the
load balancer be built with one of the defined flavors. Flavors are
defined per provider driver and expose the unique capabilities of each
provider.

This document is intended to explain the flavors capability for
operators that wish to create flavors for their users.

There are three steps to creating a new Octavia flavor:

1. Decide on the provider flavor capabilities that will be configured
   in the flavor.
2. Create the flavor profile with the flavor capabilities.
3. Create the user facing flavor.

Provider Capabilities

To start the process of defining a flavor, you will want to look at
the flavor capabilities that the provider driver exposes. To do this you
can use the provider
driver flavor capabilities API or the OpenStack client.

openstack loadbalancer provider capability list <provider>

With the default RBAC policy, this command is only available to
administrators.

This will list all of the flavor capabilities the provider supports
and may be configured via a flavor.

As an example, the amphora provider supports the loadbalancer_topology capability, among many
others:

+-----------------------+---------------------------------------------------+
| name                  | description                                       |
+-----------------------+---------------------------------------------------+
| loadbalancer_topology | The load balancer topology. One of: SINGLE - One  |
|                       | amphora per load balancer. ACTIVE_STANDBY - Two   |
|                       | amphora per load balancer.                        |
| ...                   | ...                                               |
+-----------------------+---------------------------------------------------+

Flavor Profiles

The next step in the process of creating a flavor is to define a
flavor profile. The flavor profile includes the provider and the flavor
data. The flavor capabilities are the supported flavor data settings for
a given provider. A flavor profile can be created using the flavor
profile API or the OpenStack client.

For example, to create a flavor for the amphora provider, we would
create the following flavor profile:

openstack loadbalancer flavorprofile create --name amphora-single-profile --provider amphora --flavor-data '{"loadbalancer_topology": "SINGLE"}'

With the default RBAC policy, this command is only available to
administrators.

This will create a flavor profile for the amphora provider that
creates a load balancer with a single amphora. When you create a flavor
profile, the settings are validated with the provider to make sure the
provider can support the capabilities specified.

The output of the command above is:

+---------------+--------------------------------------+
| Field         | Value                                |
+---------------+--------------------------------------+
| id            | 72b53ac2-b191-48eb-8f73-ed012caca23a |
| name          | amphora-single-profile               |
| provider_name | amphora                              |
| flavor_data   | {"loadbalancer_topology": "SINGLE"}  |
+---------------+--------------------------------------+

Flavors

Finally we will create the user facing Octavia flavor. This defines
the information users will see and use to create a load balancer with an
Octavia flavor. The name of the flavor is the term users can use when
creating a load balancer. We encourage you to include a detailed
description for users to clearly understand the capabilities of the
flavor you are providing.

To continue the example above, to create a flavor with the flavor
profile we created in the previous step we call:

openstack loadbalancer flavor create --name standalone-lb --flavorprofile amphora-single-profile --description "A non-high availability load balancer for testing." --enable

This will create a user visible Octavia flavor that will create a
load balancer that uses one amphora and is not highly available. Users
can specify this flavor when creating a new load balancer. Disabled
flavors are still visible to users, but they will not be able to create
a load balancer using the flavor.

The output of the command above is:

+-------------------+--------------------------------------+
| Field             | Value                                |
+-------------------+--------------------------------------+
| id                | 25cda2d8-f735-4744-b936-d30405c05359 |
| name              | standalone-lb                        |
| flavor_profile_id | 72b53ac2-b191-48eb-8f73-ed012caca23a |
| enabled           | True                                 |
| description       | A non-high availability load         |
|                   | balancer for testing.                |
+-------------------+--------------------------------------+

At this point, the flavor is available for use by users creating new
load balancers.