From prior threads I know that many/most WebmasterWorld members use Google Analytics or possibly Piwik with a minority doing some type of logfile analysis. However, just in case there are any others who have been using/testing real time analytics and/or Redis the following may be of interest: Introduction to Redis Streams
It is sort of, but not really, similar to Kafka. Ya, not exactly a heartfelt comparison!
Smaller players having a unified log events architecture with queries in the millisecond range capabilities is a huge ginormous competitive step.
See also: Redis Streams and the Unified Log
[brandur.org] by Brandur Leach (engineer with Stripe), 08-November-2017.
Note: TLS support for streams not available until Redis 6.0 (current are 4.0.10 stable, 5.0RC3 beta); on current timeline - approximately a year from now.
On a personal note my use case for Redis tripled with the advent of streams.
An heartfelt Bravo Zulu to Salvatore Sanfilippo (@antirez) yet again. Truly amazing work. Yet again.