6.2. Distributed image import

Distributed image import works with the glance-direct image import method, and it is enabled by default in Red Hat OpenStack Services on OpenShift (RHOSO).

When using the glance-direct image import method, users can upload local images to the Image service (glance) without any requirement for a shared storage area where API worker nodes (or replicas) stage images. Instead, staging is distributed because individual API workers have their own local and unshared staging directory. The API worker that owns the image data is the same API worker that performs the image import.

When the image is created and staged, the Image service records the URL of the staging API worker in a database. With this URL, other API workers can proxy image import requests from clients to the worker that has the image data and can perform the import operation. This workflow allows API worker nodes to be isolated for High Availability (HA) and distributed geographically for a distributed compute node (DCN) environment.