Nginx caching proxy dns name even when using variables

Rob Fulton rob at
Mon Oct 1 19:14:30 UTC 2018

On 27/09/2018 15:53, Maxim Dounin wrote:
> Hello!
> On Thu, Sep 27, 2018 at 03:27:03PM +0100, Rob Fulton wrote:
>> I’ve done some further testing on this today and discovered that
>> the configuration works correctly when the proxy_pass url is
>> accessed via http, I can see dns queries for the proxy_server
>> url every minute as per the ttl. The moment I change the url to
>> https, this stops. Is this a known limitation?
> Most likely, the problem is that you have
>      proxy_pass;
> somewhere in the configuration, without variables - so nginx
> resolves the name during configuration parsing.  As a result, your
> construct
>      set $proxy_server;
>      proxy_pass https://$proxy_server;
> does not try to resolve the name, but rather ends up using the
> existing upstream for

Thank you very much for your help, you were correct I had a proxy_pass 
directive for a 404 error page to the same hostname configured without a 
variable, setting this correctly resulted in the correct behavior.



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