how to configure varnish to drop a connection instead of sending 503?

[James Pearson]

Excerpts from Peter Jacobs's message of 2013-08-26 06:16:12 -0700:
> We have a machine with apache webserver and the apache loadbalancing module, in front of two backend machines running the same web application.
> The apache loadbalancing module has very basic functionality and only drops a backend service if it doesn't respond within a certain time. This used to work fine:  if the backend service on one machine broke down, all connections would switch to the other machine
> 
> I have put Varnish on the two backend machines (it cannot be installed on the machine with apache).

Why can't you install Varnish on your load balancer?

Have you considered replacing Apache with a dedicated load balancer, like
HAProxy?

libvmod-shield may do what you want, but this seems like an XY problem - the
proper solution is to change your architecture.

Of course, you may have a number of very good technical or political reasons
why you can't do that (I'm sure we've all been in those situations), but I feel
obliged to make sure that's actually the case, and we aren't just helping you
down the wrong path.
 - P