Load Balancing with HAProxy for MQTT

Need to cluster

IBM has a Redbook for its own IOT service environment. The book also described the topologies of enterprise MQTT service architectures. So, to cluster some mosquitto brokers, we need some other tools.

Mosquitto is a single thread process. To scale out, we need tools to better monitor and manage them.

Cue in load balancing

I followed the steps in this nice tutorial, others you googled might be just as good, as HAProxy is very easy to install, configure and run.

Use HAProxy to load balance 300k concurrent tcp socket connections: Port Exhaustion, Keep-alive and others

I’m trying to build up a push system recently. To increase the scalability of the system, the best practice is to make each connection as stateless as possible. Therefore when bottleneck appears, the capacity of the whole system can be easily expanded by adding more machines. Speaking of load balancing and reverse proxying, Nginx is probably the most famous and acknowledged one. However, TCP proxying is a rather recent thing. Nginx introduced TCP load balancing and reverse proxying from v1.9, which is released in late May this year with a lot of missing features. On the other hand, HAProxy, as the pioneer of TCP loading balacing, is rather mature and stable. I chose to use HAProxy to build up the system and eventually I reached a result of 300k concurrent tcp socket connections. I could have achieved a higher number if it were not for my rather outdated client PC.

Step 1. Tuning the Linux system