The Spark Operator is a project that makes specifying, running, and monitoring Spark applications idiomatically on Kubernetes, leveraging the new Kubernetes scheduler backend in Spark 2.3+. It follows the recent trend of using custom resources to extend the Kubernetes API and the operator pattern to extend Kubernetes with application-specific domain knowledge. The Spark Operator allows users to use declarative Spark application specifications to describe their applications, and automatically submits applications on behalf of users. It also features native cron support for running time-based Spark applications.