OpenShift Online can utilize any server implementing the Docker registry API as a source of images, including the Docker Hub, private registries run by third parties, and the integrated OpenShift Online registry.
OpenShift Online provides an integrated container registry called OpenShift Container Registry (OCR) that adds the ability to automatically provision new image repositories on demand. This provides users with a built-in location for their application builds to push the resulting images.
OpenShift Online can create containers using images from third party registries,
but it is unlikely that these registries offer the same image notification
support as the integrated OpenShift Online registry. In this situation
OpenShift Online will fetch tags from the remote registry upon imagestream
creation. Refreshing the fetched tags is as simple as running
<stream>. When new images are detected, the previously-described build and
deployment reactions occur.
OpenShift Online can communicate with registries to access private image repositories using credentials supplied by the user. This allows OpenShift to push and pull images to and from private repositories. The Authentication topic has more information.