Hello Damien.
Thank you for your proposal, I appreciate!
But, as I can see/read, Fastly operates the same way as Varnish when the
backend is overloaded (it rejects new connections):
https://docs.fastly.com/en/guides/common-503-errors#error-503-backendmax_conn-reached
The "Waiting room" could be an option (but this is not what I try to
achieve because it throttles clients):
https://developer.fastly.com/solutions/patterns/waiting-room/
However, I prefer to stick to GPL or Open-Source projects and HAProxy
seems perfect to regulate the traffic sent to the backend. ;-)
Regards.
Le 17/06/2020 à 15:08, Damien Wetzel a écrit :
Hi Tranxène50
I'm a reseller of Fastly in France a cdn based on a fork of varnish 2
maybe it could be a solution to minimize the backend traffic you receive
somehow ?
i can make you test if needed
akamai has a solution they call waiting room, to regulate the traffic to the
origin,
i think this is the kind of things to try to achieve ?
Best Regards,
Damien
tranxene50 writes:
> Hello!
>
> Many thanks for your answers! :-)
>
> @Dridi:
>
> You are right, writing a specific VMOD would be the ideal solution but
unfortunately I am not qualified for the job. ^^
>
> By the way, I would like to thank all the people who are working hard to
enhance and maintain Varnish.
>
> This software is absolutely awesome!
>
> @Xavier:
>
> Before considering HAProxy, I searched if quick and dirty hacks were
possible with iptables to limit simultaneous connexions and tc to shape the
traffic.
>
> But, after a quick reading of the documentation of HAProxy, it became clear
that - as you said - it is a reliable solution.
>
> So, thanks the for the hint!
>
> Have a great day!
>
> Le 16/06/2020 à 00:17, Xavier Leune a écrit :
>
> Hello,
>
> @tranxene50 if implementing a vmod can be very challenging, using
haproxy can be a great solution here. Please refer to this blog post:
> https://www.haproxy.com/fr/blog/four-examples-of-haproxy-rate-limiting/
(or in french ;)
https://www.haproxy.com/fr/blog/four-examples-of-haproxy-rate-limiting/ ). The
very first step is about setting a
> maximum connections number and a queuing. Using haproxy as your backend
would require low engineering and a minimum overage.
>
> Regards,
>
> Le lun. 15 juin 2020 à 20:02, Dridi Boukelmoune <[email protected]> a
écrit :
>
> Bonsoir,
>
> Unfortunately we don't have any sort of queuing on the backend side,
> so besides implementing your own backend transport from scratch in a
> VMOD there is currently no solution.
>
> Cordialement,
> Dridi
>
> On Sun, Jun 14, 2020 at 2:32 AM tranxene50
> <[email protected]> wrote:
> >
> > Hello!
> >
> > Please forgive my bad English, I live in France.
> >
> > Summary: how to cache - with Varnish - Open Street Map PNG images
without overloading OSM tiles servers?
> >
> > The question seems related to Varnish backends and
".max_connections" parameter.
> >
> > A far as I know, if ".max_connections" is reached for a backend,
Varnish sends 503 http errors.
> >
> > I understand the logic but would it be possible to queue these
incoming requests and wait until the selected backend is really available?
> >
> > backend a_tile {
> > .host = "a.tile.openstreetmap.org";
> > .port = "80";
> > .max_connections = 2;
> > }
> >
> > If Varnish have, let's say 100 incoming requests in 1 second, how can I
handle this "spike" without overloading the backend?
> >
> > All my google searches were "dead ends" so I think the question
is poorly formulated.
> >
> > Note 1 : using [random|round_robin] directors could be a
temporary solution
> > Note 2 : libvmod-dynamic is great but does not limit backend
simultaneous connexions
> >
> > Many thanks for your help!
>
>
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