Sensor or Decorator?
There are two extensions extension points that enables allow plugins to save measures: Sensor and Decorator. A common problem when writing a plugin is to decide which one to use.
A Sensor is invoked once during the analysis of a project. The sensor can invoke a maven plugin, parse a flat file, connect to a web server... For example the Cobertura Sensor invokes the Codehaus Cobertura MOJO. Then the generated XML file is parsed is able to parse the cobertura XML report file generated during execution of your tests and used to save the first-level of measures on resources (project, package or class).
A sensor can access and save measures on the whole tree of resources. Sensor are generally used to add measure at the lowest level of the resource tree.
Decorators are triggered once all sensors have completed. Their decorate method is called on every resource of a certain level bottom up. Decorators can load (SELECT) read and save (INSERT) measures. The call is contextual, i.e it is only possible to access the resource and its children.
Decorators are generally used to consolidate at higher levels measures that have been added by Sensors at the lowest level.
How to Reuse Existing Components
Extensions are registered in an IoC container, with constructor injection. To communicate with other extensions or with existing components provided by the API, just declare them in the constructor of your extension. For example to get references on DatabaseSession or RulesProfile:
You should never directly instantiate classes which implements implement BatchComponent or ServerComponent , because they should be retrieved as an IoC dependency. Otherwise it leads to issues with backward compatibility.
How to Quickly Start the Plugin
As described in the Getting Started page, you can build sources, copy the JAR file to the directory extensions/plugins/ and restart the server. But this approach can quickly become tedious. The following solutions help to edit code without leaving your development environment:
The sonar-dev-maven-plugin allows to lets you start a SonarQubeserver SonarQube server and to deploy the your plugin.
Once the server is launched, hit http://localhost:9000. By default, the in-process database (H2, or Derby prior to SonarQube 3.2) is used but you can specify to use a local MySQL instance instead with the property "-Dsonar.database=mysql". In that case, the sonar schema must exist in the MySQL DB along with the user sonar/sonar (login/password) who which must have all rights on the sonar schema.
# Note that SonarQube versions greater than or equal 4.0 are not supported yet mvn install org.codehaus.sonar:sonar-dev-maven-plugin::start-war -Dsonar.runtimeVersion=3.07.2
Then you can feed the database by inspecting projects:
Add the property -Djava.io.tmpdir=/tmp to the mvn command.
Changes on Java code are not reloaded dynamically. You need to rebuild the plugin and to re-execute sonar-dev-maven-plugin.
Debug Java batch
mvnDebug sonar:sonar and attach your IDE to the remote process. Example in Intellij Idea: Run > Edit configurations > Add new configuration > Remote.
Debug a plugin
- Unzip a sonar distribution
- Edit the conf/wrapper.conf file and uncomment the line : wrapper.java.additional.3=-agentlib:jdwp=transport=dt_socket,server=y,address=8000
- Copy your plugin's jar file to extensions/plugins
- Launch SonarQube with the standard command. The following line will appear in the log : Listening for transport dt_socket at address: 8000
- Attach the IDE to the debug process on port 8000
- Set breakpoints in the source code
We've gathered all our debugging tips into this page.
How to Use External Libraries
A plugin benefits from all the dependencies provided by the API. Execute the following command on your plugin to list them:
- Libraries used for GWT compilation must be defined with scope provided
- The plugin classloader is a child of the Sonar classloader, with a parent-first delegation model. There are two consequences:
- Sonar libraries are automatically inherited. Their versions can not be changed.
- There are side-effects on some libraries, for example the classloader must be explicitly set for XStream:
Code Block java java
XStream xstream = new XStream(); xstream.setClassLoader(getClass().getClassLoader());
How to Log
SLF4J is used as a simple facade of various logging frameworks (log4j, commons-log, logback, java.util.logging). It's simple to use:
Read the SLF4J manual for more details.
How to Get Configuration
org.sonar.api.config.Settings provides properties for batch extensions (global/project settings, command-line parameters, system properties) and server extensions (global settings, system properties, file $SONAR_HOME/conf/sonar.properties). It replaces Apache Commons Configuration that is deprecated since release 2.12.
Persistent properties are also accessible from the Web Service named 'properties'. To exclude some properties from anonymous requests, add the suffix ".secured" to the key (
my.property.secured). It can be useful for license keys for example.
Steps to cover a new language
- Write the grammar. This is the hardest part.
- Write a parser (a parser simply takes a grammar, an input, and will parse it, yielding a parse tree).
- Test your grammar, to ensure it is able to parse your real-life language files.
- Write a few parse tree visitors. Some visitors will compute metrics, while others will enforce coding rules. A dozen or so visitors is sufficient for an initial release.
- Write a SonarQube sensor to launch the visitors. It should query the API to get the list of source files, the list of active coding rules in the quality profile, and the API to save metrics and issues.
Tips and Tricks
- For generating charts use d3.js, which is packaged with SonarQube since version 4.1.
- To create "template" rules (rules that can be duplicated by the user) set the rule's
- To access a constant from a Java class in a .erb file, use J