Find stack trace for workflow job launched from Oozie coordinator

I have a bare-bones Oozie coordinator with this specification:

<coordinator-app name="my-coord" frequency="${coord:days(1)}"
                 start="${startDate}" end="${endDate}" timezone="UTC"
                 xmlns="uri:oozie:coordinator:0.4">
    <controls>
        <timeout>${timeout}</timeout>
    </controls>
    <action>
        <workflow>
            <app-path>${workflow}</app-path>
        </workflow>
    </action>
</coordinator-app>

It launched the workflow job around the scheduled nominal start time. But later, logs showed the workflow job entered its fail-state. To retrieve job info, I ran:

oozie job -info 0000909-190113225141152-oozie-oozi-W

which supplied useful information, including the following exception trace:

] Launcher exception: org.apache.spark.SparkException: Application application_1547448533998_26676 finished with failed status
org.apache.oozie.action.hadoop.JavaMainException: org.apache.spark.SparkException: Application application_1547448533998_26676 finished with failed status
        at org.apache.oozie.action.hadoop.JavaMain.run(JavaMain.java:59)
        at org.apache.oozie.action.hadoop.LauncherMain.run(LauncherMain.java:51)
        at org.apache.oozie.action.hadoop.JavaMain.main(JavaMain.java:35)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.oozie.action.hadoop.LauncherMapper.map(LauncherMapper.java:242)
        at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:54)
        at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:453)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
        at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:422)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1724)
        at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
Caused by: org.apache.spark.SparkException: Application application_1547448533998_26676 finished with failed status
        at org.apache.spark.deploy.yarn.Client.run(Client.scala:1122)
        at org.apache.spark.deploy.yarn.Client$.main(Client.scala:1169)
        at org.apache.spark.deploy.yarn.Client.main(Client.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:738)
        at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:181)
        at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:206)
        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:121)
        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.oozie.action.hadoop.JavaMain.run(JavaMain.java:56)
        ... 15 more

Unfortunately, this stack trace -- evidently produced from SparkSubmit -- says nothing about why my workflow job (a Scala program) actually failed.

This seems like a common enough scenario -- workflow logic failing and triggering its own stack trace.

Is there some other place to look for such stack traces in the Hadoop / Oozie / Coordinator / Workflow setup?

Use yarn applications -list to view a list of jobs running on the Hadoop cluster. Then follow these steps:

1. Search through the resulting list of applications for a reference to the name of your Scala program (launched from the Oozie workflow job).
2. Get the application ID shown for the Scala program.
3. Then run yarn logs -applicationId <application_ID>.

Resulting logs should show your Scala program logs interspersed with other logs not produced by the Scala program. It helps if your Scala program embeds a unique prefix in each logging directive so you can filter your program logs from others.