The Java action doesn't get a lot of the "magic" that we do in the other actions, so things don't always behave right for users using the Java action to launch MapReduce jobs. We've seen some confusion where these jobs were picking up the mapred-default properties and not working because of it. It would be great if we could document how to use the job conf prepared by Oozie, which includes the proper mapred-site.xml (and other site files), plus anything in the <configuration> section of the Java action.
Basically, they just need to create their job conf with something like this (taken from MapReduceMain.java):
Configuration actionConf = new Configuration(false); actionConf.addResource(new Path("file:///", System.getProperty("oozie.action.conf.xml")));
We can put it next to the already documented snippet about the delegation token propagation here: http://oozie.apache.org/docs/4.0.0/WorkflowFunctionalSpec.html#a3.2.7_Java_Action