Tuesday, November 11, 2014

(Update) Work-around for Oozie's limited hdfs command arsenal

DISCLAIMER: I do not offer any warranty for the below provided code, run at your own risk!!!

UPDATE:

Turns out I jumped the gun on the whole python script inside Oozie, it is absolutely possible, it's just in six hours of trial and error, I haven't found a solution yet! Oozie is at it's best, drains my life's blood and sanity. Either way, the shell script will work and it's been running fine for me for the last week. The Python script works on it's own but in the confines of Oozie, it doesn't know where the executable is. If you can get subprocess.Popen to work, shoot me a comment, I will greatly appreciate it.

I have a love-hate relationship with Oozie. Truthfully, it's more hate than love though. Consider scenario, you need to create time-stamped directories, there are no built-in expression language functions available to just do it out of the box. You're forced to come up with all kinds of hacks to get what you want out of Oozie. What I used to do was, create a shell action calling a shell command to generate a timestamp:

echo "output="`date '+%Y%m%d%H%M'`

then in the workflow, I'd do this:






and later in the workflow:



but what if you have requirement to create time-stamped output path within your mapreduce code, like monthly, quarterly, yearly, bi-yearly, etc and then within those directories, you'd have child directories, for example the final path would be:


/etl/prod/quarterly/2014Q3/abc
/etl/prod/quaterly/2014Q3/xyz


I wanted something simple that just worked. So what I did was create a shell script like so:


















Of course, you need to adjust fields to match your requirements but in general, this is what I had to do. Then, after wrangling with all this shell code, I realized I could've just written a Python script to have better control over the process. Here's the Python version:




























You may as well write a better shell or Python version, but this works for me. Happy Oozieing!






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