Currently, there are two ways to achieve KMS HA.
The first one, and the only documented one, is running multiple KMS instances behind a load balancer. https://hadoop.apache.org/docs/stable/hadoop-kms/index.html
The other way, is make use of LoadBalancingKMSClientProvider which is added in
HADOOP-11620. However the usage is undocumented.
I think we should update the KMS document to introduce LoadBalancingKMSClientProvider, provide examples, and also update kms-site.xml to explain it.