Hi, You want to use probes and the fallback director.
Relevant documentation: to define a probe: https://varnish-cache.org/docs/6.4/reference/vcl.html?highlight=probe#probes to attach it to backends: https://varnish-cache.org/docs/6.4/reference/vcl.html?highlight=probe#backend-definition the fallback director: https://varnish-cache.org/docs/6.4/reference/vmod_directors.html?highlight=fallback#directors-fallback i also wrote these blog posts a long time ago, but they are still valid: https://info.varnish-software.com/blog/backends-load-balancing https://info.varnish-software.com/blog/backends-load-balancing-part-2 The first one goes through probes, and the second one explores directors, including the fallback one. Hope that helps -- Guillaume Quintard On Sat, Jul 4, 2020 at 7:14 AM hamidreza hosseini <[email protected]> wrote: > Hi, > I want to have 2 or 3 backends in the Varnish config file but just one of > them workes as an active backend and whenever my active backend failed , > the second backend become active and respond the requests. (In other hand, > I dont want to have two backend for responding clients and just one of them > works at the same time, and it check the health status of my active backend > , whenever it is was unhealthy , varnish switch to the second or third > backend.) > Best Regards. > _______________________________________________ > varnish-misc mailing list > [email protected] > https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >
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