These require use of nmred/kafka-php 0.1.0, which is from 2015.
Upstream has had one major release since then, in 2017. There have
been various commits, issues, and pull requests since but nothing
released for five years.
EventRelayer was created for use with WANObjectCache, where WMF
considered use of Kafka as one of the possible transports. This never
happened, and WANObjectCache has not supported EventRelayer since 2019,
removed with change I328eb74f21c23.
The EventRelayer abstraction itself remained unused, until it became
re-purposed for CdnCacheUpdate, which WMF now relays via EventBus.
Monolog KafkaHandler is no longer used, and was similarly created for
WMF's use case. It seems unlikely to be of interest to most third
parties. And those larger installs like WMF would likely be more
interested in SyslogHandler which is more standardised across the
industry (especially for cloud native tooling around containers).
Someone using this can continue to do this by adding a similar class
to their own code instead, possibly published as an extension.
Deprecating this in MW 1.38 (with backport) means we can remove it
shortly after in master, and no longer maintain this unused/untested
integration for which no known users exist, as well as remove our
supported suggested dependency on the unmaintained kafka-php lib.
Change-Id: I475227293ca050acead357efebce12e93a971f65
3dec1399ac