MetalLB is a load-balancer implementation for bare metal Kubernetes clusters, using standard routing protocols.
MetalLB is a young project, so you should treat it as an alpha system. The project maturity page explains what that implies.
Kubernetes does not offer an implementation of network load-balancers (Services of type LoadBalancer) for bare metal clusters. The implementations of Network LB that Kubernetes does ship with are all glue code that calls out to various IaaS platforms (GCP, AWS, Azure…). If you’re not running on a supported IaaS platform (GCP, AWS, Azure…), LoadBalancers will remain in the “pending” state indefinitely when created.
Bare metal cluster operators are left with two lesser tools to bring user traffic into their clusters, “NodePort” and “externalIPs” services. Both of these options have significant downsides for production use, which makes bare metal clusters second class citizens in the Kubernetes ecosystem.
MetalLB aims to redress this imbalance by offering a Network LB implementation that integrates with standard network equipment, so that external services on bare metal clusters also “just work” as much as possible.
MetalLB requires the following to function:
The concepts section will give you a primer on what MetalLB does in your cluster.
Want to test-drive MetalLB? Follow the tutorial to set up a self-contained MetalLB in minikube.
We welcome contributions in all forms. Please check out the contributing guide for more information.
One lightweight way you can contribute is to tell us that you’re using MetalLB, which will give us warm fuzzy feelings :).