The private IP of an Amazon Elastic Compute Cloud (Amazon EC2) instance is retained throughout its lifecycle. However, the private IP might change during a planned or unplanned system crash; for example, during an Amazon Machine Image (AMI) upgrade. In some scenarios, retaining a private static IP can enhance the performance and recovery time of workloads. For example, using a static IP for an Apache Cassandra seed node prevents the cluster from incurring a rebalancing overhead.
This pattern describes how to attach a secondary elastic network interface to EC2 instances to keep the IP static during rehosting. The pattern focuses on Cassandra clusters, but you can use this implementation for any architecture that benefits from private static IPs.
