This document outlines various steps and notes for operators to consider when upgrading their Ironic-driven clouds from previous versions of OpenStack.
The Ironic service is tightly coupled with the Ironic driver that is shipped with Nova. Currently, some special considerations must be taken into account when upgrading your cloud from previous versions of OpenStack.
When upgrading a cloud from Juno to Kilo, users must ensure the Nova service is upgraded prior to upgrading the Ironic service. Additionally, users need to set a special config flag in Nova prior to upgrading to ensure the newer version of Nova is not attempting to take advantage of new Ironic features until the Ironic service has been upgraded. The steps for upgrading your Nova and Ironic services are as follows:
Note that during the period between Nova’s upgrade and Ironic’s upgrades, instances can still be provisioned to nodes, however, any attempt by users to specify a config drive for an instance will cause error until Ironic’s upgrade has completed.