HTTPInternalServerError 500 response is returned to the user while
image server is down during downloading the image. When glance tries
to download the image from the remote location (image server) which
is down, Connection refused ECONNREFUSED error is raised on the
glance server.
Raised RemoteServiceUnavailable exception from glance_store and handle
it in v1 and v2 api's to return 503 HTTPServiceUnavailable response
to user.
Note: Please refer below link to check glance_store related changes
which addresses this issue partially.
I065b9a3e8e674ea74ff8563aad99d7d022417caa
Closes-Bug: #1379798
Change-Id: I45099153e75d53b028e249fad8a4d944d38adf65
6982284218