Parameterised Scheduler Plugin

“VJ, I want you to run the automation job on all our three environments on a nightly basis. So that we can compare the results & find out any discrepancies across environments.”

My team lead said this to me one day out of the blue.A small background on this – we have automation scripts used to test Rest APis on our cloud. This normally runs on a single environment every night, mainly pre-prod.Now the requirement was to run the same set of scripts on all environments i.e staging/dev, pre-prod & prod.

This was a new and exciting task for me and I got on with it right away!

Till now, I only knew how to schedule a job periodically as I had earlier written a blog post regarding it. But I did not know how to schedule the same job, multiple times with different parameters.

I found exactly what I needed in the Parameterised Scheduler Plugin!!

So once you install this plugin,restart the jenkins application for it to take effect. Very important. I tried scheduling it without restart and the plugin did not work.

Here’s how you can schedule the same job multiple times throughout the day with different parameters:-


The % symbol separates the cron notation from the parameters(if any) that you want to give for your run. ‘env’ is my parameter which my scripts pick up.

Another example of scheduling the same job with multiple parameters :-


The parameters have to be separated by a ; for it to take effect. Here ‘env’ and ‘param’ are 2 params that my automation scripts accept.

So there’s the solution for it.Hope this post was helpful to some.

I love Jenkins for it’s plug-ability & wide range of solutions to commonly faced problems/requirements. Simply  superb!

Alright guys.. Have fun… Enjoy 🙂

This is VJ signing off!




Nil, empty and blank in Ruby

.nil? can be used on any object and is true if the object is nil.

.empty? can be used on strings, arrays and hashes and returns true if:

String length == 0 or Array length == 0 or Hash length == 0

Running .empty? on something that is nil will throw a NoMethodError.

That is where .blank? comes in. It is implemented by Rails and will operate on any object as well as work like .empty? on strings, arrays and hashes.

nil.blank? == true
false.blank? == true
[].blank? == true
{}.blank? == true
"".blank? == true
5.blank? == false
0.blank? == false

.blank? also evaluates true on strings which are non-empty but contain only whitespace:

"  ".blank? == true
"  ".empty? == false

Rails also provides .present?, which returns the negation of .blank?.

sudo /etc/init.d/jenkins start not working

I had installed jenkins and builds were working fine.

Suddenly it stopped working. There is nothing in logs

I tried starting it, with the following command :-

sudo /etc/init.d/jenkins start

but still it’s not running

root@localhost:$# service jenkins restart
 * Restarting Jenkins Continuous Integration Server jenkins [ OK ] 

root@localhost:$# service jenkins status
Jenkins Continuous Integration Server is not running

After some googling I was able to get to run jenkins with the foll command :-

-Djava.awt.headless=true -jar /usr/share/jenkins/jenkins.war –webroot=/var/cache/jenkins/war –httpPort=8080

Still not able to get why the conventional Jenkins start command is not working. I’m working on ubuntu 14.04 version. So maybe there is some issue with Jenkins-Linux combination. To get it working is enough for the time being!

Sending Arguments in Command Line while running RSpec tests

Suppose you want to run your rspec specs on various product environments & at run-time you want to mention where you would like the scripts to run, you can create a command line parameter say ENVIRONMENT and assign it a value like this :-

ENVIRONMENT= “dev” rspec spec/sanity_test_spec.rb

Similarly you can assign it values like prod, preproduction etc.

In your spec files you can retrieve the parameter value like this :-

runtime_param = ENV[‘ENVIRONMENT’]
puts “Evironment value got on runtime is #{runtime_param}”

The keyword ‘ENV’ is a built-in ruby term(I suppose) which handles this functionality.