How do I set the driver's python version in spark?
You need to make sure the standalone project you're launching is launched with Python 3. If you are submitting your standalone program through spark-submit then it should work fine, but if you are launching it with python make sure you use python3 to start your app.
Also, make sure you have set your env variables in ./conf/spark-env.sh (if it doesn't exist you can use spark-env.sh.template as a base.)
I'm using spark 1.4.0-rc2 so I can use python 3 with spark.  If I add export PYSPARK_PYTHON=python3 to my .bashrc file, I can run spark interactively with python 3.  However, if I want to run a standalone program in local mode, I get an error:

Exception: Python in worker has different version 3.4 than that in
driver 2.7, PySpark cannot run with different minor versions

How can I specify the version of python for the driver?  Setting export PYSPARK_DRIVER_PYTHON=python3 didn't work.