I am not sure if Patroni provides load balancing feature.
It depends on understanding of load-balancing:
- If we talk about load balancing read-only traffic across multiple replicas - it is very easy to achieve with Patroni.
- If we talk about parsing all queries in order to figure out whether they are read-write or read-only, then no.
BUT, even if there is a solution that parses queries to make a decision it I would not recommend anyone to use it unless all consequences are understood.
Specifically, not every read-only query could be salefy sent to a replica, because they could be lagging behind the primary.
Only application (developers) could decide whether for a specific query they could afford slightly outdated results. Most of the popular application frameworks support configuring two connection strings for this purpose.