http 500 errors are not cached but go to the backend

[brama]

Hi Maxim,

> Just a side note: the fastcgi_cache_lock directive doesn't affect 
> update of the cache, it only affects adding new items to the 
> cache.  To handle cache updating the "fastcgi_cache_use_stale 
> updating" should be used (it's actually already in your config).
> 
Ok, that's good to know.

> The
> 
>    fastcgi_cache_use_stale http_500;
> 
> in your config instructs nginx to don't cache 500 response but 
> return stale cached content instead.  As soon as original cached 
> resource expires - nginx starts to ask backend about new response, 
> but since 500 is returned it returns stale response to clients 
> instead.
> 
> In your case the behaviour looks a bit confusing as "original 
> cached resource" above is the same 500 response (cached as 
> fastcgi_cache_use_stale don't affect initial content caching), but 
> the behaviour is as expected with your configuration - when you 
> ask nginx to cache 500 responses and to don't use 500 responses 
> for cache update at the same time.
> 
Ok, got it. That was indeed confusing. Thanks for your explanation.

Bram

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,234691,234782#msg-234782