Bug 1552583

The glance-direct method requires a shared staging area when used in a HA configuration. Image uploads using the 'glance-direct' method may fail in an HA environment if a common staging area is not present. Incoming requests to the controller nodes are distributed across the available controller nodes. One controller handles the first step and another controller handles the second request with both controllers writing the image to different staging areas. The second controller will not have access to the same staging area used by the controller handling the first step. Glance supports multiple image import methods, including the 'glance-direct' method. This method uses a three-step approach: creating an image record, uploading the image to a staging area, and then transferring the image from the staging area to the storage backend so the image becomes available. In an HA setup (i.e., with 3 controller nodes), the glance-direct method requires a common staging area using a shared file system across the controller nodes. The list of enabled Glance import methods can now be configured. The default configuration does not enable the 'glance-direct' method (web-download is enabled by default). To avoid the issue and reliably import images to Glance in an HA environment, do not enable the 'glance-direct' method.