Loadbalancing between 2 locations
Hello everyone!
My friend and I have each bought an optiplex server. Our goal is to selfhost a web app (static html) with redundancy. If my server goes down, his takes over and vice versa. I've looked into Docker Swarm, but each server has to be totally independent (each runs its own apps, with a few shared ones).
I can't find a solution that allows each server to take over and manage loadbalancing between the two. Ideally with traefik, because that's what we're currently using. To me the real issue is the DNS A record that point to only one IP :(
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Your challenge is that you need a loadbalancer. By hosting the loadbalancer yourself (e.g. on a VPS), you could also host your websites directly there...
My approach would be DNS-based. You can have multiple DNS A records, and the client picks one of them. With a little script you could remove one of the A Records of that server goes down. This way, you wouldn't need a central hardware.
Where would you host the script? If it's expected that the server that fires it off is always online and performing health checks, why not have it host a load-balancer? Or another local instance of the website? It's something fun to play around with, but if this is for anything beyond a fun exercise there are much better ways to accomplish this.
I'd host it on both webservers. The script sets the A record to all the servers that are online. Obviously, the script als has to check it's own service.
It seems a little hacky though, for a business use case I would use another approach.
That's an interesting idea, need to check if they offer some kind of a API for that.
But then there is this other thing, what about dns cache?
Set the DNS cache time to 60 seconds.
Set the script to run on every host delayed by some time to avoid simultaneously accessing the API (e.g. run the script every other minute).
With this approach, you get automatic failover in at most 3 minutes.
The VPS remains this single point of failure :(
The DNS-based approach seems to be the best bet for my use case.