In part 1 of this series here, I explained the basics of SonarQube plug-ins and how to start writing your own plug-in. In part 2 here, I explained how to define custom metrics and sensor classes to collect metric data (measures). In part 3 here, I showed the basics of how to create custom widgets to present to users the information we are collecting from analysed projects.
Now finally in part 4, I will show how to test and deploy your plug-ins, and some tips to make development and testing workarounds quicker, like configuring JRebel to speed up development.
Part 4 – Testing and Deploying
If you have been following this series of blog posts, you already have a simple structure for a plug-in, hopefully doing something useful and showing valuable insights from your code and configuration.
So what’s next? How can we test and deploy our plug-ins? The simple naïve answer is: package and deploy it to a working SonarQube instance, as you would do with any other plug-in.
Packaging the plug-in is as easy as executing Maven’s package goal. The Maven configuration, governed by the sonar-plugin packaging type, will ensure that the right classes and configuration files are packaged in the right way. The resulting Jar file will be ready for deployment into a SonarQube instance.
Deploying the plug-in is also an easy task. If you are a seasoned SonarQube user, you probably know how to install and update public plug-ins from SonarQube update center. Unfortunately this way is only available for plug-ins listed in the public SonarQube directory, and is not suitable for our own in-house, internal-only plug-ins. In our case, we would need to manually copy the packaged plug-in file to our SonarQube instance, in the folder extensions\downloads, and then restart SonarQube. This is actually what the update center does: downloading a plug-in file from Internet and place it in downloads folder, so it is picked up automatically in next restart.
Although the process above is simple and easy to automate with a script, it is lengthy. Moreover, it needs a local SonarQube instance that you need to manage, and that it’s subject to get polluted by other plug-ins or just by normal user usage. Fortunately, SonarQube provides with a better alternative way to test a plug-in.
SonarQube Development Mode
To prevent developer’s sanity, SonarQube provides with a development mode. This development mode will automate the deploy process as a Maven plug-in, downloading a SonarQube instance from the internet if needed and running it as a child process of the Maven process.
To launch the development mode, just issue this command:
mvn install org.codehaus.sonar:sonar-dev-maven-plugin:1.7:start-war -Dsonar.runtimeVersion=3.7.3
You may setup an alternate version of SonarQube to host and run the plug-in as needed. The SonarQube instance spawned by this command will run on default settings: listening on port 9000, with embedded H2 database.
Once ready, just launch a SonarQube analysis, either using SonarQube Maven plug-in or using SonarQube Runner standalone analysis. The analysis will connect by default to the server in development mode and run your plug-in as part of the analysis process.
Optimized Testing with JRebel
Although SonarQube development mode is nice and very convenient, it has a fundamental problem – it is slow! It takes quite a few minutes to have the environment prepared, and if you find a bug or want to improve something, and you need to change some Java code, you have to drop it and start the process again.
Fortunately, JRebel comes to a rescue and can dramatically speed up the process. The same that JRebel monitors Java web containers and injects changes in Java bytecodes directly into the running JVM that hosts the web container, without loosing state – effectively saving you the few (or many) minutes needed to redeploy and/or restart the web container – JRebel can monitor our plug-in under development.
To configure JRebel, just add JRebel configuration and agent to the developer mode launch script.
JRebel configuration is just a simple rebel.xml file under src/main/resources folder, which content is set to monitor the right folder where Java classes are compiled into:
<?xml version="1.0" encoding="UTF-8"?>
<application xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.zeroturnaround.com" xsi:schemaLocation="http://www.zeroturnaround.com http://www.zeroturnaround.com/alderaan/rebel-2_0.xsd">
Then, add the JRebel agent to the development mode launch command:
mvn install org.codehaus.sonar:sonar-dev-maven-plugin:1.7:start-war -Dsonar.runtimeVersion=3.7.3 -Dsonar.containerArgs=-javaagent:C:\java\tools\jrebel-5.5.2\jrebel.jar -Drebel.log=true
This is possible thanks to sonar.containerArgs command-line options, kindly provided by ZeroTurnaround support team as a merge request into open-sourced SonarQube development mode plug-in. Who said vendor support does not work?
Once launched with JRebel, the development mode may remain active during the full development and testing session, without needing to redeploy or restart it again, and picking changes done in plug-in classes.
Evenmore, if the SonarQube analysis is launched with JRebel agent active, each subsequent SonarQube analysis process that is executed will pick changes in the plug-in, effectively making the plug-in code to be ‘reloaded’ automatically, without needing to redeploy it again. To do that, don’t forget to add this to the SonarQube analysis command:
mvn sonar:sonar -javaagent:c:\java\tools\jrebel-5.5.2\jrebel.jar
It is easy to get started with custom plug-in development in SonarQube if you know where to start. Although open-source plug-ins are a good source of useful information, the online documentation lacks of a good plug-in 101 guide. I really hope that this short blog post series has been of help, it allows you to connect all the pieces that confirms a plug-in, and encourages you to conceive and bring to life your own custom plug-ins, either analysers, reporters or integrators with other existing tools.