One of the requirements for a build tool is to be able to generate repeatable builds. In a project, the build tool should behave identically for all team members. While a project guideline can be made on the version of Java or Maven to be used, it would be easier if it could be enforced automatically.
This is where the Maven Enforcer plugin comes in.
- Open a simple project (
project-with-enforcer). - Add the following plugin configuration:
<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.3.1</version> <executions> <execution> <id>enforce-versions</id> <goals> <goal>enforce</goal> </goals> <configuration> <rules> <requireMavenVersion> <version>3.2.3</version> </requireMavenVersion> <requireJavaVersion> <version>1.8</version> </requireJavaVersion> </rules> </configuration> </execution> </executions> </plugin> - Build the project using Java 7 and Maven 3.2.3:
mvn clean package. - Observe the output:
The Enforcer plugin uses the rules configuration and validates the project against the rules. If it finds violations, it reports the error(s) and does not proceed with the build.
In the preceding example, our project had two issues:
The Maven Enforcer plugin has several other rules to enforce various constraints. A couple of them are as follows:
It is also possible to implement custom enforcer rules. One such is available at https://github.com/ferstl/pedantic-pom-enforcers.