XDP Virtual Server: An eBPF Load Balancer library

Faced with the looming retirement of our traditional load balancer appliances we decided to give XDP a try. Facebook's Katran library did not support layer 2 switching, which was still a requirement, so we built an eBPF application in C and a supporting library with Golang.

We came across a few issues along the way - driver support for network cards gave me headaches - but on the whole eBPF has made what would have been practically unthinkable a few years ago into a relatively straightforward task.

The library is used by an application which adds configuration management, BGP, metrics, etc., and after testing on smaller services for some time the balancer now handles streaming audio and website content for the UK's largest commercial radio broadcaster, delivering tens of gigabits per second to our audience. COTS servers handle high volumes of traffic and can be trivially scaled/migrated when updated hardware comes along as simply as running an Ansible job.

The library

The application