After completing all of your individual service upgrades, you should perform a complete package upgrade on all of your systems:
# yum upgrade
This will ensure that all packages are up-to-date. You may want to schedule a restart of your OpenStack hosts at a future date in order to ensure that all running processes are using updated versions of the underlying binaries.
After you have upgraded each service, you should test to make sure
that the service is functioning properly. You will also want to
review any new (*.rpmnew) configuration files installed by the
upgraded package.
New versions of OpenStack services may deprecate certain configuration options. You should also review your OpenStack logs for any deprecation warnings, because these may cause problems during a future upgrade.