Including (or referring to) the git revision in your maven build

Problem

I am writing customized test ware for one of my personal projects (more on it in another post). The test ware does a few things and at the end stores the test results in a relational database. I wanted to be able to link each database record to the specific git commit from which the code under test was produced. I have used a similar technique with svn in the past but did not know how to do this with git. Also I wanted to automate it using my CI pipeline (maven, Jenkins, Sonar).

Solution

After a bit of googling I found Mattias Severson's excellent post. He explains how to inject the git SHA-1 hash sum into the maven ${buildNumber} variable. Then he lists a few ways in which this variable can be propagated in the build (e.g. manifest entry, property file, static method call, etc.). I am not going to repeat any of these implementations here - you can check out the "Advertise the Build Number" section of his post. Just would like to add to his list another implementation which I decided to use in this particular case:

Injecting the git revision in a VM parameter for the maven surefire plugin

The Junit tests are run by the maven surefire plugin. It spawns its own java VM and you can pass a custom parameter to the VM of the form -Dparam.name=param.value. The "trick" is to link the ${buildNumber} variable to the VM parameter. This can be done in the pom.xml in this way:

	<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-surefire-plugin</artifactId>
	<version>2.14.1</version>
	<configuration>
	<redirectTestOutputToFile>true</redirectTestOutputToFile>
	<!-- I added the second parameter only because of the buildnumber plugin -->
	<argLine>-Dpdf2xml=${pdf2xml} -Dgit.version=${buildNumber}</argLine>
	</configuration>
	</plugin>

view raw pom-surefire.xml hosted with ❤ by GitHub

The VM parameter than can be read from the JUnit tests at execution time:

System.getProperty("git.version")

That's it. For completeness' sake I am listing below my entire pom.xml:

	<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.iw.pdfEx</groupId>
	<artifactId>pdfEx</artifactId>
	<packaging>jar</packaging>
	<version>1.0-SNAPSHOT</version>
	<scm>
	<!-- XXX is my git repo: the buildnumber plugin needs it-->
	<connection>scm:git:XXX</connection>
	</scm>
	<properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	</properties>
	<dependencies>
	<dependency>
	<groupId>junit</groupId>
	<artifactId>junit</artifactId>
	<version>4.10</version>
	<scope>test</scope>
	</dependency>
	<dependency>
	<groupId>org.apache.directory.studio</groupId>
	<artifactId>org.apache.commons.io</artifactId>
	<version>2.4</version>
	</dependency>
	</dependencies>
	<build>
	<plugins>
	<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-surefire-plugin</artifactId>
	<version>2.14.1</version>
	<configuration>
	<redirectTestOutputToFile>true</redirectTestOutputToFile>
	<!-- I added the second parameter only because of the buildnumber plugin -->
	<argLine>-Dgit.version=${buildNumber}</argLine>
	</configuration>
	</plugin>
	<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-compiler-plugin</artifactId>
	<version>3.1</version>
	</plugin>
	<plugin>
	<groupId>org.codehaus.mojo</groupId>
	<artifactId>buildnumber-maven-plugin</artifactId>
	<version>1.1</version>
	<executions>
	<execution>
	<phase>validate</phase>
	<goals>
	<goal>create</goal>
	</goals>
	</execution>
	</executions>
	</plugin>
	</plugins>
	</build>
	</project>

view raw pom.xml hosted with ❤ by GitHub