5s hangs with http2 and variable-based proxy_pass

[Valentin V. Bartenev]

On Monday 10 October 2016 12:34:18 Chris West wrote:
> If you enable http2, our proxy setup develops 5s hangs, under load.
> This happens from at least Chrome/linux, Firefox/linux and Edge/win10.
> 
> Any suggestions on how to further diagnose this problem, or work out
> where this "5 second" number is coming from? Full reproduction config
> and debug logs are attached, but I don't understand the debug logs.
> 
> 
> This isn't always reproducible, but happens frequently. Changing
> browser, restarting nginx, ... doesn't cause it to be immediately
> reproducible.
> 
[..]
> 2016/10/10 11:17:31 [debug] 4058#4058: *238 http2 frame complete
> pos:00007F536315501D end:00007F536315501D
> 2016/10/10 11:17:36 [debug] 4058#4058: *238 http upstream resolve:
> "/proxy/nettesto....?"
> 2016/10/10 11:17:36 [debug] 4058#4058: *238 name was resolved to 94.23.43.98
> 2016/10/10 11:17:36 [debug] 4058#4058: *238 name was resolved to
> 2001:41d0:2:2c62::
[..]


Looks like the delay is created by your resolver (8.8.4.4 as set in your configuration).
Please, also check the documentation and don't use any public DNS in the resolver
directive: http://nginx.org/en/docs/http/ngx_http_core_module.html#resolver

 | To prevent DNS spoofing, it is recommended configuring DNS servers in a properly
 | secured trusted local network.

 wbr, Valentin V. Bartenev