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<p class="MsoNormal">Thanks, Guillaume! I may follow up with you separately to discuss this in more depth since this could help with a redesign of our architecture that I’d like to do.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Justin<o:p></o:p></p>
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<p class="MsoNormal"><b>From:</b> Guillaume Quintard <guillaume@varnish-software.com>
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<b>Sent:</b> Monday, June 14, 2021 7:54 AM<br>
<b>To:</b> Justin Lloyd <justinl@arena.net><br>
<b>Cc:</b> varnish-misc@varnish-cache.org<br>
<b>Subject:</b> Re: Varnish HA and MediaWiki HTTP PURGEs<o:p></o:p></p>
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<p class="MsoNormal">Hello Justin!<o:p></o:p></p>
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<p class="MsoNormal">VHA is a commercial product, so we should probably keep it short of private as this is an open-source mailing-list.<o:p></o:p></p>
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<p class="MsoNormal">However, since I'm sure the answer will be useful for other people, let's answer publicly :-)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">VHA is a fire-and-forget tool, outside of the critical path so that replication requests failing (or being rate-limited) don't cause harm.<o:p></o:p></p>
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<p class="MsoNormal">Purging, on the other hand, needs to be very vocal about failed purge requests failing as your cache consistency is at stake, so while VHA can do it, it's a bad idea.<o:p></o:p></p>
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<p class="MsoNormal">However, VHA uses a tool named broadcaster which can be used on its own to do exactly what you need: replicate a single request for the CMS backend to the whole cluster, and report back so you can act on failures.<o:p></o:p></p>
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<p class="MsoNormal">Cheer,<o:p></o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">Guillaume Quintard<o:p></o:p></p>
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<p class="MsoNormal">On Mon, Jun 14, 2021 at 7:39 AM Justin Lloyd <<a href="mailto:justinl@arena.net">justinl@arena.net</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi all,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I just saw the new
<a href="https://www.youtube.com/watch?v=KhqVdKe2RAU" target="_blank">Varnish HA video</a> and was wondering if VHA’s node synchronization would obviate the need for all of the Varnish nodes to be listed in the
<a href="https://www.mediawiki.org/wiki/Manual:Varnish_caching" target="_blank">MediaWiki Varnish caching configuration</a>. MediaWiki uses the list of cache nodes to send HTTP PURGE requests to invalidate cached pages when they are updated. So with VHA, could
MediaWiki just be configured with a single hostname or floating IP address (e.g. keepalived) that points to the Varnish cluster so that the cluster could handle replicating the PURGE requests?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Justin<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
varnish-misc mailing list<br>
<a href="mailto:varnish-misc@varnish-cache.org" target="_blank">varnish-misc@varnish-cache.org</a><br>
<a href="https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc" target="_blank">https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc</a><o:p></o:p></p>
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