Trait Based Networking

Introduction

Trait Based Networking, or TBN for short, is an Ironic feature that allows an Openstack installation utilizing Ironic, Neutron, and Nova to dynamically configure port scheduling for Ironic nodes.

Enable and Configure

To configure and enable TBN for your Ironic installation please see Configure Trait Based Networking to Plan Networking Related Operations at vif Attach

Terminology

First some terms:

  • Node: An Ironic node.

  • Trait: A set of actions referred to by a name.

  • Action or Trait Action: A defined operation to apply to a node if the action’s Filter Expression matches network objects associated with a node.

  • Filter Expression: A boolean expression which filters for specific network objects like a port, portgroup or network.

  • Port: A network interface.

  • Portgroup: A set of ports, grouped together.

  • Dynamic Portgroup: An ephemeral portgroup that is created by a trait’s action and is subsequently destroyed once detached.

  • Network (aka VIF): A neutron network.

Trait Actions

The core of TBN functionality lies in actions that each trait defines. Each action allows the operator to define how exactly TBN will setup networking for the node.

The following actions are available:

  • Attach port: Attach one or more ports belonging to a node to a network (aka vif).

  • Attach portgroup: Attach one or more portgroups belonging to a node to a network (aka vif).

  • Group and attach ports: Create a dynamic portgroup and attach it to a network.

In the future more actions may be added.

See Trait Based Networking Configuration File Reference for more information on configuring and applying trait actions.

Filter Expression Primer

Filter Expressions are how network related objects are filtered or matched with their applicable traits.

Let’s look at a basic filter expression:

port.vendor == "purple"

This expression consists of three parts:

  1. A named variable: port.vendor - This means the expression will consider a port’s vendor field.

  2. A comparator: == - In this case equality.

  3. A string literal: "purple" - Gives a comparison value to compare against the contents of the named variable.

Taken together this expression can be read in plain English as: ‘filter for ports with vendor that is exactly equal to the string “purple”’.

All available variables and comparators are listed in the Filter Expression Reference.

Single expressions can be linked together using boolean operators:

  • “&&” boolean AND

  • “||” boolean OR

Like so:

port.vendor == "purple" && port.category != "privatenet"

Again, in plain English this could be read as: ‘filter for ports with vendor that is exactly equal to the string “purple” and whose category field is not “privatenet”’.

Functions

There’s also a couple of functions available to filter ports vs portgroups:

  • port.is_port will return true if the port is a port, and false otherwise.

  • port.is_portgroup will return true if the port is a portgroup, and false otherwise.

Function expressions can be used in isolation:

port.is_port

Or linked with other expressions:

port.is_port && port.vendor == "green"