openstack-manuals/doc/config-reference/source/object-storage/cors.rst

Cross-origin resource sharing

Cross-Origin Resource Sharing (CORS) is a mechanism that allows code running in a browser (JavaScript for example) to make requests to a domain, other than the one it was originated from. OpenStack Object Storage supports CORS requests to containers and objects within the containers using metadata held on the container.

In addition to the metadata on containers, you can use the cors_allow_origin option in the proxy-server.conf file to set a list of hosts that are included with any CORS request by default.