ExecuteGroovyScript gives InstantiationException

[#1]

Hello

I am trying to add an ExecuteGroovyScript processor. A simple example test works fine, but when I try to add my script it does not initiate. Exception (on hoover over) is really brief: InstantiationException thrown by groovy invokehelper. 

Script uses some external jars. As far as I can see I added those to the classpath. 

I am probably doing something stupid but I was wondering how to debug this issue? The log files do not seem to contain anything wrt this error which makes troubleshooting very difficult

All tips warmly welcomed!

Tx

Peter

[#2 · Accepted solution]

This is quite a broad question and hard to troubleshoot all at once.

A general approach: 

1. Analyze your custom code and identify all bits of complexity/all dependencies

2. Run the standard example

3. Introduce in a very minimal fashion one complexity/dependency from your custom code into the standard

4. If it works, repeat step 3

This should allow you to narrow down exactly what is causing the problem (and hopefully guide the resolution).

[#3]

Hello,

Tx for your reaction Dennis. I was able to continue. 

The reason I was having issues seemed to be related to the fact that the Groovy script was a standard class with a static main method. It makes sense that Nifi does not accept that I guess, but the process of diagnosing such issue might be made easier imo. It was a trial and error task, and as you suggested, by starting from an example.

Anyway, I am good now 🙂

Regards

Peter