Blog: Blixt - A load-balancer written in Rust, using eBPF, born from Gateway API

In SIG Network we now have a layer 4 (“L4”) load balancer named Blixt. This project started as a fun experiment using emerging technologies and is intended to become a utility for CI and testing to help facilitate the continued development of Gateway API. Are you interested in developing networking tools in Rust and eBPF ? Or perhaps you’re specifically interested in Gateway API? We’ll tell you a bit about the project and how it might benefit you. Blixt originated at Kong as an experiment to test load-balancing ingress traffic for Kubernetes clusters using eBPF for the dataplane. Around the time of Kubecon Detroit (2022) we (the Gateway API maintainers) realized it had significant potential to help us move our TCPRoute and UDPRoute support forward, which had been sort of “stuck in alpha” at the time due to a lack of conformance tests being developed for them. At the same time, various others in the SIG Network community developed an interest in the project due to the rapid growth of eBPFs use on Kubernetes. Given the potential for benefit to the Kubernetes ecosystem and the growing interest, Kong decided it would be helpful to donate the project to Kubernetes SIGs to benefit upstream Kubernetes. Over several months we rewrote the project in Rust (from C), due to a strong contingency of Rust knowledge (and interest) between us developing the project and an active interest in the burgeoning Aya project (a Rust framework for developing eBPF programs). We did eventually move the control plane (specifically) to Golang however, so that we could take advantage of the Kubebuilder and controller-runtime ecosystems. Additionally, we augmented our custom program loader (in eBPF, you generally write loaders that load your BPF byte code into the kernel) with bpfman : a project adjacent to us in the Rust + eBPF ecosystem, which helps solve several security and ergonomic problems with managing BPF programs on Linux systems. After the recently completed license review process , which provided a blanket exception for the use of dual licensed eBPF in CNCF code, the project became officially part of Kubernetes and interest has been growing. We have several goals for the project which revolve around the continued development of Gateway API, with a specific focus on helping mature Layer 4 support (e.