Spark UI on AWS EMR

Question

I am running a AWS EMR cluster with Spark (1.3.1) installed via the EMR console dropdown. Spark is current and processing data but I am trying to find which port has been assigned to the WebUI. I've tried port forwarding both 4040 and 8080 with no connection. I'm forwarding like so

ssh -i ~/KEY.pem -L 8080:localhost:8080 hadoop@EMR_DNS

1) How do I find out what the Spark WebUI's assigned port is? 2) How do I verify the Spark WebUI is running?

Answer 1

Here is an alternative if you don't want to deal with the browser setup with SOCKS as suggested on the EMR docs.

1. Open a ssh tunnel to the master node with port forwarding to the machine running spark ui

   ssh -i path/to/aws.pem  -L 4040:SPARK_UI_NODE_URL:4040 hadoop@MASTER_URL
   

   MASTER_URL (EMR_DNS in the question) is the URL of the master node that you can get from EMR Management Console page for the cluster

   SPARK_UI_NODE_URL can be seen near the top of the stderr log. The log line will look something like:

   16/04/28 21:24:46 INFO SparkUI: Started SparkUI at http://10.2.5.197:4040
   

2. Point your browser to localhost:4040

Tried this on EMR 4.6 running Spark 2.6.1

Answer 2

Spark on EMR is configured for YARN, thus the Spark UI is available by the application url provided by the YARN Resource Manager (http://spark.apache.org/docs/latest/monitoring.html). So the easiest way to get to it is to setup your browser with SOCKS using a port opened by SSH then from the EMR console open Resource Manager and click the Application Master URL provided to the right of the running application. Spark History server is available at the default port 18080.

Example of socks with EMR at http://docs.aws.amazon.com/ElasticMapReduce/latest/DeveloperGuide/emr-web-interfaces.html