Comment 3 for bug 1398838

From the Glance's perspective, I think the response content type should follow the content type http request provided/required, currently glance only support application/json [0] (and that's the reason why only json serializer and de-serializer was implemented there), other project followed this approach as well, e.g. cinder support json and xml request so there are two kinds of serializer and de-serializer. IMO the fault stuff need to follow this rule as well, e.g. cinder one [1], so glance could just return json content.

[0] https://github.com/openstack/glance/blob/master/glance/common/wsgi.py#L535
[2] https://github.com/openstack/cinder/blob/master/cinder/api/openstack/wsgi.py#L1260

But I see the point this bug reported, so from end user's opinion, a human readable with nice error message would be better, so I think we can just format it in client side. And more, I think keep server always return the response with requested content-type is better for non-human client - a code/application handling.

Base on my above thoughts, in sort, IMO, we could fix this in glanceclient directly instead of changing glance server side.