As we had discussed previously, there are keys which we would like them to use the WarmUpRoute so to relieve some of the network traffic between our app servers and our memcached cluster.
SRE has created and deployed a mcrouter route called /*/mw-with-onhost-tier, which right now is configured exactly like the /*/mw route. The configuration which will route /*/mw-with-onhost-tier to use the WarmUpRoute can be enabled per MediaWiki server by setting profile::mediawiki::mcrouter_wancache::use_onhost_memcached to true.
We now need to have MediaWiki add the /*/mw-with-onhost-tier prefix to keys we want to be read from the onhost memcached, for instance the WANObjectCache keys. After this is deployed to MediaWiki, we can start gradually roll out to all clusters and test it in production.