Metrics without a value are now emitted as NaN instead of various values (KIP-386)
Updated kafka-topics.sh tool—it now uses the AdminClient API and does not require access to zookeeper anymore (KIP-377)
All command line tools now accept the --help flag (KIP-374)
Last month, the community submitted 10 KIPs (KIP-438 to KIP-447). These are the ones that caught my eye:
KIP-440: Extend Connect Converter to support headers
At the moment, Kafka Connect Converters don’t support message headers. In environments that rely on a lot of headers, this makes it impossible to use Connect to import or export messages. This KIP aims at fixing this discrepancy and allowing Converters to use headers.
KIP-444: Augment metrics for Kafka Streams
Operating Streams applications is currently relatively hard due to the lack of several key metrics. This KIP aims at addressing these issues and started doing a full review of all existing Streams metrics. The idea is to remove metrics that turned out not useful and provide new metrics to allow better monitoring and ease debugging.