nginx cache issue (http upstream cache: -5)

[loopback_proxy]

Ahhh interesting, that did the trick. Thank you so much. 

I have been also trying to understand the internals of nginx caching and how
it works. I read the nginx blog about the overall architecture and the nginx
man page about proxy_cache_* directives. I am looking for the internal
architecture of the how the caching subsystem works. If you guys have any
documentation or article about it, that would be so useful. 

- Karthik

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,278346,278370#msg-278370