They have Kafka, ElasticSearch, some workflow engine thing, and they manage a distributed object store (Swift) deployment.
Apparently in Wikimedia's case they also have a stated company policy / philosophy around self-managed infrastructure that prevents them from using public cloud for a bunch of stuff (I've heard this from a former employee but can't find any further documentation about it).
You're not wrong, but they are slightly more complicated than that: https://meta.wikimedia.org/wiki/Wikimedia_servers
They have Kafka, ElasticSearch, some workflow engine thing, and they manage a distributed object store (Swift) deployment.
Apparently in Wikimedia's case they also have a stated company policy / philosophy around self-managed infrastructure that prevents them from using public cloud for a bunch of stuff (I've heard this from a former employee but can't find any further documentation about it).