Comment 4 for bug 1581111

The comments in glance-api.conf read:

# List of stores enabled. Valid stores are: cinder, file, http, rbd,
# sheepdog, swift, s3, vsphere (list value)
#stores = file,http

So I think you should add "swift" to the list, to have something like:

[glance_store]
stores=file,http,swift
...

Then restart the glance-api service, and try again. Does this solve your issue?