Apache Storm: How to add external JARs or packages into CLASSPATH while running 'storm jar'?

I have been playing with 'storm-kafka' and 'storm-hbase' lately. Basically, they are projects/tools that one can use to integrate Kafka and HBase with storm.

My project was to have Kafka as spout and HBase as bolt. In other words, my application will pull data from Kafka and then write the output to HBase. In other other words (pun intended :), I need to have the storm-kafka and storm-hbase JAR included when I run my Storm topology.

There are a few ways to do this:
(1) Put the JARs under STORM_BASE_DIR
(2) Put the JARs under STORM_BASE_DIR/lib
(3) Put the package under STORM_CONF_DIR
(4) Include the package into the topology JAR

After trying the above few methods, my favourite is method #4. However, it is not without its own pain points.

Let me explain why I do not like the other methods.

Method #1
=======
By putting JARs into STORM_BASE_DIR, I have a feeling that I have 'corrupted' the directory. Messing up a standard directory of a product is not my cup of tea.

Method #2
=======
See Method #1 above.

Method #3
=======
Since the storm.py codes do not search the directory declared as STORM_CONF_DIR (or USER_CONF_DIR) for JARs, you would have to put the package files in that directory. How many times have I said 'messy'? :)

Now, let's discuss Method #4. I say it is my favourite, but I never say it is the best. That is because it will grow your JAR file size greatly if you have some really big external JARs to include (beside your topology). However, I feel that it is the most acceptable approach because it is more manageable than the other methods (at least to me :).

Hence, if you are looking into including or adding external JARs while running your Storm topology, I would suggest you to include those JARs into your topology JAR for the time being until there is a neater way to do this!

NOTE:
Environment = HDP 2.2 (Storm 0.9.3)

Source codes of storm.py and how CLASSPATH is determined

Apache Storm: Integration with Kafka using Kafka Spout

If you have been playing with either Apache Kafka or Apache Storm, you would have read so much articles about integration between the two. From my experience, reading too much can be a bad thing sometimes (pun intended :). In this case, there were multiple efforts that try to offer such integration. Thus, it might caused confusion about which is the best or standard way to do it.

It is good to know that starting from version 0.9.2-incubating, Apache Storm has decided to include such support officially. Read more here.

Anyway, how does such integration work?

In this blog entry, I am only going to share information about using Kafka as a Storm spout. Yes, starting from Storm version 0.9.3, you can use Kafka as a bolt too. If you want to know more about Topology, Spout and Bolt, read this.

Basically, the classes you need for the Storm-Kafka integration are available under storm.kafka.* package. 

If you want to get up to speed quick, try out the sandbox offered by Hortonworks here. After you have downloaded the sandbox (or if you are gutsy enough to install the system through Ambari), it is advisable to try out the tutorial too. If you want to jump straight to the tutorial related to the Storm-Kafka integration, you can go here. Please take note that the tutorial contains the source codes too, so make sure you check them out!

Once you get a hang of it, you can move over to this website to learn more about Storm Kafka.

If you do not want to compile the Storm Kafka package yourself, you can download it from the Hortonworks maven repository.

The information offered here should get you going for a while, and I will share some tips and traps regarding the integration in future entries.

Happy hacking!