In this chapter, we'll learn how to customize the health check, based on metrics of your distributed system.
Note: this in currently in development mode, not yet ready for production.
Helix provides the ability for each node in the system to report health metrics on a periodic basis.
Helix supports multiple ways to aggregate these metrics:
Helix persists the aggregated value only.
Applications can define a threshold on the aggregate values according to the SLAs, and when the SLA is violated Helix will fire an alert. Currently Helix only fires an alert, but in a future release we plan to use these metrics to either mark the node dead or load balance the partitions. This feature will be valuable for distributed systems that support multi-tenancy and have a large variation in work load patterns. In addition, this can be used to detect skewed partitions (hotspots) and rebalance the cluster.