Requesting Image Memberships

We want to see a list of the other system tenants (or users, if "owner_is_tenant" is False) that may access a given virtual machine image that the Glance server knows about. We take the `uri` field of the image data, append /members to it, and issue a GET request on the resulting URL.

Continuing from the example above, in order to get the memberships for the first public image returned, we can issue a GET request to the Glance server for http://glance.example.com/images/1/members. What we will get back is JSON data such as the following:

{'members': [
 {'member_id': 'tenant1',
  'can_share': false}
 ...]}

The `member_id` field identifies a tenant with which the image is shared. If that tenant is authorized to further share the image, the `can_share` field is `true`.