Weird issue that I think I’ve stumbled upon earlier, but yet again reared it’s head yesterday. Certain application containers (possibly Jetty in this case) will for some reason not produce any output from Solr (or other applications I’d guess) if the request is made with HTTP/1.0 as the version identifier (“GET /…/ HTTP/1.0” as the first line of the request). The native HTTP support in PHP identifies itself as HTTP/1.0 as it doesn’t support request chunking, which then turns into a magical problem with requests that used to work, but doesn’t work any longer (the response is just zero bytes in size – all other headers are identical) – but still works as expected if you open them in your browser.
The solution is to either gamble on the server not sending any chunked responses and then setting protocol_version in the stream context that you pass to the file retrieving function (the list of HTTP wrapper settings (.. I don’t think it’s a good idea to define protocol_version as float, but .. well.)), or use cURL instead. The Solr pecl extension uses cURL internally, so it’s not affected by this issue.