Load balancing Nexus artifact repository
Sonatype's Nexus 3 Pro supports High Availability through a couple of mechanisms that are collectively known as Component Fabric:


Peer-to-peer Repository Managers means there is no one master, also known as a single point of failure.  Packages are replicated between the nodes to ensure they are eventually consistent.
Storage Backends mean you can use high durability storage such as S3.
Dynamic Nodes enable auto-scaling support to increase capacity when demand is high and decrease it when demand is low to reduce costs.


It's not really in Sonatype's interests to support HA for the community project as it would cannibalize some of the enterprise customers from their paid product.