Minor Description
I configured my Kafka brokers as follows:
listeners=plaintext://kafka01:9092,ssl://kafka01:9093
With this config, my Kafka brokers start, print out all of the config properties, and exit quietly. No errors, nothing in the log. No indication of a problem whatsoever, let alone the nature of said problem.
Then, I changed my config as follows:
listeners=PLAINTEXT://kafka01:9092,SSL://kafka01:9093
Now they start and run just fine.
Per RFC-3986:
When a URI uses components of the generic syntax, the component
syntax equivalence rules always apply; namely, that the scheme and
host are case-insensitive and therefore should be normalized to
lowercase. For example, the URI <HTTP://www.EXAMPLE.com/> is
equivalent to <http://www.example.com/>.