Devs,
In our full deployment environment I could not get the Kafka forwarding
of logs to work. I kept getting Kafka errors on the AM trying to lookup
the topic. Seeing as how I had been able to get this same runnable
working in a unit test environment I figured it had to do with the
classpath. Looking deeper I saw that the AM runs with the
application.jar contents on its classpath. Why is that? It seems to me
that the runnable classpaths should never be part of the AM.
I changed the TwillLauncher to not use the application.jar for the AM
classpath and got a CNFE in the AM for jsimpleopt.OptionSpec. It seems
this is an implicit dependency of Kafka that is not currently discovered
by the dependency mechanism (presumably because Kafka is written in
Scala). When I added jsimpleopt-3.2.jar to my classpath and as a
dependency class for the AM everything worked! I was not getting the
CNFE when application.jar/lib/* was on the classpath so something in my
application libs must have been picked up by Kafka initialization.
IMO, the AppMaster is internal Twill code and its dependencies should be
fully provided by the distribution and self-contained. That may present
some build challenges, but users should not ever run into this stuff.
I'll file and ticket and submit a PR if there is agreement on this, but
the application.jar/lib/* being on the AM classpath seems pretty
intentional from looking at the code.
Cheers,
-Martin
- classpath for the appmaster Martin Serrano
-
