Saint mode

[Javier Frias]

On Tue, Sep 1, 2009 at 4:58 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>wrote:

>
>
>
> 503's are never cached to my knowledge.
>
> the rest can be obtained by:
>
>        sub vcl_fetch {
>                if (beresp.status != 200 && beresp.status != 404) {
>                        set beresp.ttl = 0;
>                        return (pass);
>                }
>        }
>
>

So my setup is a bit different, since I'm one of those that want to server
stuff pass the grace period, if my backends are down. I also want to protect
myself against a self inflicted DoS due to errors. So ideally, saint mode is
what i'd like ( ie, dont store this unless you are a better result )

here's the pertinent configs...

sub vcl_recv {
 ....
        # even though an object may be expired, we want to serve it up for
this long to prevent thread pile up
        # we also want to be somewhat aggresive if the backend is
up(healthy)
       if (req.backend.healthy) {
               set req.grace = 5m;
       } else {
               set req.grace = 600m;
       }
...
}

sub vcl_fetch {
       # here, we cache for more time codes that are not server errors
        if ( obj.status <500) {
                set obj.grace = 600m;
                set obj.ttl = 600s;
                set obj.cacheable = true;
        } else {
                set obj.grace = 5s;
                set obj.ttl = 60s;
                set obj.cacheable = true;
        }

}



Before, i use to just have a blanket vcl_fetch setting my grace and ttl,
which is probably the reason why i was caching the 500's



-Javier
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