balancer

A simple client side load balancer for go applications.

balancer was made to provide easier access to DNS-based load balancing for go services running in kubernetes and was mainly built for http.Client.

Grpc has its own DNS load balancer, use that one.

Scope

This project does not do health checking and does not monitor status of any hosts. This is left up to decide for a consul DNS or kubernetes DNS, and assumes hosts returned are deemed healthy.

This library does not retry or otherwise try to fix problems, leaving this up to the caller.

balancer currently assumes that a lookup will return a non-empty set of initial hosts on startup.

TODO

• Any logging?
• Decide on a few error scenarios:
  • netbalancer: implement a timeout?
  • netbalancer: DNS lookup returned 0 hosts
  • netbalancer: DNS lookup returned error. We just log the error, effectively ignoring it
    • on error, return lookup error?
    • setting the hostlist to empty on error seems a bit drastic
      • on lookup error, we keep the old list and log error
• Tests
• Use option-func to configure debug mode (extra logging)

Known limitations

• No health checking of hosts.
• netbalancer does not respect TTL of dns records as this is not exposed by the Go code.