proxy_upstream_next while no live upstreams

[Maxim Dounin]

Hello!

On Wed, May 10, 2017 at 10:27:16PM +0800, Wu Bingzheng wrote:

> Maybe you miss something in Question 2. The server 192.168.0.5 never fails.
> I think nginx should not return 502 if there is at least one server never fails.
> Exactly speaking, the server never fails in the last 1 hour and the fail_timeout is the default 10 second.

How do you know that the server never fails?

The "no live upstreams" error indicate that it failed from nginx 
point of view, and was considered unavailable.

Note that "failure" might not be something specifically logged by 
nginx, but a response with a specific http code you've configured 
in proxy_next_upstream, see http://nginx.org/r/proxy_next_upstream.

-- 
Maxim Dounin
http://nginx.org/