Servers need to be available for a successful configuration reloading about pgcat

[film42]

I believe this is also true for starting pgcat. I noticed if postgresql is offline, pgcat will not boot because it cannot validate. Imagine you just had a postgresql database blow up and while someone is working on fixing it, you push a configuration change to pgcat which needs a reload or a restart (depending on how you deploy it). Neither can happen because your teammate is still working on getting the db server to boot. I don't think it makes sense to make pgcat wait for postgres to be up before starting.

This issue should solve both of those problems.

As an impl idea: The connection pools cached server info params should be read-through. If they are not currently stored, when a client connects to pgcat, we should attempt to fetch server info params on-demand. If we are unable to do so, reject the client connection. If we are, accept the connection and cache the params for the next client who connects. We should refresh this cache (make an attempt to) when we validate a new config on reload or boot. Thoughts?

[levkk]

That would work!

[levkk]

Should be fixed. Feel free to reopen if any issues arise.