FlashMQ is a high-performance, light-weight MQTT broker/server, designed to take good advantage of multi-CPU environments.
Builds (zip and a Debian apt server) are provided on www.flashmq.org.
Building from source can be done with build.sh.
Official Docker images aren't available yet, but building your own Docker image can be done with the provided Dockerfile.
# build flashmq docker image
docker build . -t halfgaar/flashmq
# run using docker (with, as an example, a place for a config file (default
# name flashmq.conf). Create extra volumes as you need, for the persistence DB
# file, logs, password files, auth plugin, etc.
docker run -p 1883:1883 -v /srv/flashmq/etc/:/etc/flashmq halfgaar/flashmq
# for development you can target the build stage to get an image you can use for development
docker build . --target=build
See www.flashmq.org