ironic/doc/source/drivers/ipa.rst

Ironic Python Agent

Overview

Ironic Python Agent (also often called IPA or just agent) is a Python-based agent which handles ironic bare metal nodes in a variety of actions such as inspect, configure, clean and deploy images. IPA is distributed over nodes and runs, inside of a ramdisk, the process of booting this ramdisk on the node.

For more information see the ironic-python-agent documentation.

Drivers

Starting with the Kilo release all drivers (except for fake ones) are using IPA for deployment. There are two types of them, which can be distinguished by prefix:

• For drivers with pxe_ or iscsi_ prefix IPA exposes the root hard drive as an iSCSI share and calls back to the ironic conductor. The conductor mounts the share and copies an image there. It then signals back to IPA for post-installation actions like setting up a bootloader for local boot support.
• For drivers with agent_ prefix the conductor prepares a swift temporary URL for an image. IPA then handles the whole deployment process: downloading an image from swift, putting it on the machine and doing any post-deploy actions.

Which one to choose depends on your environment. iSCSI-based drivers put higher load on conductors, agent-based drivers currently require the whole image to fit in the node's memory.

Requirements

Using IPA requires it to be present and configured on the deploy ramdisk, see BuildingDeployRamdisk for details.