[Overview + Motivation]
Cloud software is complex. Resources abstracted at the Cloud layer must be realized on backend system(s) (native Operating System or other potentially distributed service(s)) and an association between the Cloud and backend resource must be maintained and kept in sync with each other. Regardless of how well we code and/or test our systems, sometimes unforeseen circumstances occur that cause the resource associations to become out of sync.
Often times one or more resources in the association are deleted and others are left behind. For example, connectivity errors while a delete operation is running in the Cloud cause the backend resource to not be (fully) cleaned up. This situation is often referred to as "orphaned objects / resources". Remediation of such circumstances not only requires the technical "know how", but also orphaned resource identification. Failure to remediate leads to resource leakage among other potential problems within the Cloud and/or backend systems.
[Proposed Solution]
The Pluggable Backend Association Mapping (PBAM) extension for neutron aims to address these issues by giving OpenStack neutron administrators additional visibility and remediation capabilities across heterogeneous (services, plugins, etc.) neutron backend resource mappings. Using the unified consistent northbound REST API provided by the extension, admins can quickly inventory and identify orphaned resources within neutron. They can then use the same consistent API to clean-up or re-create those orphaned backend resources as necessary.
Today, we see OpenStack consumers writing their own orphaned resource clean-up scripts and/or struggling to ensure resource mappings are in sync. What we propose here is a neutron core extension that automates this task, easing the administrative burden that exists today.
[Resources]
[1] PBAM PoC including DHCP Agent mappings reference implementation and python-neutronclient bindings and documentation on the PoC, it's API, etc.:
https://github.com/bodenr/neutron/tree/feature/pbam
[2] Video demo:
https://www.youtube.com/watch?v=qAY8U8vgbzc
It seems like there's a lot of overlap with another proposal:
https:/