Certain Artifacts can't be resolved from a gems virtual repository due to their dependencies creating too long of a query parameter list.
This affect Gem versions > 2.1
One example is package aws-sdk. Note how the GET request has an incredibly long query parameter list.
Works with remote, and seems the 502 is not handled well on virtual:
Debug loggers don't give extra information, it could be something related to that 502 error, as that's the big difference in the outputs.
The long URL through cURL or Browser gives out the following for remote repository requests:
<h1>Error 502 Bad Gateway</h1>
<p>Details: cache-sjc3633-SJC 1525229284 1719933408</p>
<p>Varnish cache server</p>
For Virtual repositories, it simply returns a close bracket symbol " ] ".