I found an interesting postgres cluster management system using Pacemaker. It is created by GoCardless. They provide a vagrant box, so we can play and learn it easily.

Five years ago, I was interested in Postgres-XC , currenty called Postgres-X2, and made a multi-GTM (global transaction manager) system for it.

Though I had forgotten this work for a long time, I found its executable files from my old PC a month ago (unfortunately the source code of them was lost). They perfectly run, so I provide a Vagrant box to run my old program on your PC.