infrastructure setup using ESI

[Cosimo Streppone]

On Thu, 21 Oct 2010 23:14:53 +0200, Gresens, August  
<AGresens at scholastic.com> wrote:

> Where does Varnish typically reside in the network architecture? I would
> imagine in a scenario in which we would be using ESI, we would want
> Varnish in front of the application load balancers
>
> [...]
>
> We were also considering if Varnish could be used much farther
> downstream - in between the load balancer and the application

Until last week, we were using varnish as in:

   Interwebz -> LVS -> Nginx fronts -> Varnish -> Backend LVS -> Backends

That is essentially our pre-existing architecture, where we
"injected" varnish, to try and do the least possible damage.

That was a year ago. Lots of stuff happened, and we realized
Varnish can help us a bit more.

Last week, we shifted varnish in 2nd position:

   Interwebz -> LVS -> Varnish -> Nginx fronts -> Backend LVS -> Backends

We built a very simple shields-up configuration, meant
to prevent backends overloading, with a low ttl (5-10s),
and we entirely avoid caching:

- !GET requests (POST, HEAD, ...)
- requests from logged in users

It's been working fine so far.

We're setting up load testing to find out
the max traffic level we can handle :)

-- 
Cosimo