IPVS-TXT-LB

What?

Create an IPVS Load Balancer from a list of 'real servers' in a TXT record.

Why?

My initial motivation is for a Kubernetes control plane - and not use an external load balancer for the API servers, which means they can stay behind a firewall and not on the public internet, and no separate load balancing server is required; they just need to be able to make a DNS query to obtain a list of peers (to whom they already have access over a private network).

In general, this could be useful in any case where:

• you have a set of machines on a common network
• each machine needs to talk to one of the others, but it doesn't matter which
• you don't want a separate load balancer
• you can query a DNS record from the machines, and keep it up to date with the machine list from outside (e.g. CI/CD)

How?

1. Install ipvsadm
2. Put ipvs-txt-lb somewhere that's in $PATH
3. Put ipvs-txt-lb.service in /etc/systemd/system/ and run systemctl enable ipvs-txt-lb
4. Put ipvs-txt-lb.conf in /etc/ and populate it
5. Populate your TXT record with a ;-delimited list of servers, e.g. alpha;beta
6. Run systemctl start ipvs-txt-lb