For example, I want to mute Sending N messages to ... logged at info level by ruby-kafka,
while keeping logging info messages from other places.

For some use-cases, this may be treated as a liveness check.
While in others it produces a bunch of messages, which not only wastes space but makes reading logs harder (especially when there is some other metrics mechanism included
or other app-oriented logs).

For those still wanting to mute this (and if they use https://github.com/reidmorrison/semantic_logger),
it's possible to configure a custom logger for the library:

logger = SemanticLogger[Kafka]

Log at :warn level

And this way skip messages at :info. Other loggers, could still log :info messages.

logger.level = :warn

or only change level to a warning if keeping logs at info but keep if debug is set:

logger.level = :warn if logger.info?

Quite a drastic option, as there are other useful logs you may like to see on production.

Filter unwanted logs

Define what you want to filter (in this case means what to select - show in the logs)

logger.filter = lambda do |log|
  return true unless log.message

  !log.message.match?(/\ASending \d  messages to /)
end

This gives you more control over what you want to mute.
Also in this case I'd not set this filter when the main logger (like Rails.logger) is set to :debug level.

Links:

• Change noisy log from info to debug #914