Amazon EMR
Amazon EMR Release Guide

Accessing the Spark Web UIs

You can view the Spark web UIs by following the procedures to create an SSH tunnel or create a proxy in the section called Connect to the Cluster in the Amazon EMR Management Guide and then navigating to the YARN ResourceManager for your cluster. Choose the link under Tracking UI for your application. If your application is running, you see ApplicationMaster. This takes you to the Spark application driver's web UI at port 4040 wherever the driver is located. The driver may be located on the cluster's master node if you run in YARN client mode. If you are running an application in YARN cluster mode, the driver is located in the ApplicationMaster for the application on the cluster. If your application has finished, you see History, which takes you to the Spark HistoryServer UI port number at 18080 of the EMR cluster's master node. This is for applications that have already completed. You can also navigate to the Spark HistoryServer UI directly at http://master-public-dns-name:18080/.