HN user
I really wonder why people go for implementing their own HA stack when there's Pacemaker or rgmanager available?
First: There's a functional resource agent available to handle PostgreSQL. It handles single instances or multiple ones.
Second: Zhe whole cluster-thing can be very complex. You can have a LOT of fail scenarios and I wouldn't recommend to anyone to try to catch them all.
Selling free software is perfectly legal as long as you provide the source code. That's what Stallman itself said countless number of times. The "free" in free software stands for "freedom", not "free beer".
I definitely accept this way of bringing money in the project. Software development is time-intensive labour and time is money. You all know that, do you?
Some mentioned "Let the business-people pay" (better known as "Open Core"-model). This is only working if businesses are interested. Elementary OS doesn't target business usage or has business-relevant elements, so that will go nowhere.