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 : > 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! > > 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 > _______________________________________________ > varnish-misc mailing list > [email protected] > https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >
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