How to use properties-maven-plugin?

Question

I'd like to use properties-maven-plugin. I read the usage http://mojohaus.org/properties-maven-plugin/usage.html , but it's not working for me.

I created a very simple project to test it. Here is my 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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>test</groupId>
  <artifactId>MavenTest</artifactId>
  <version>1.0.0</version>
  <name>MavenTest</name>

  <properties>
    <prop1>2.2</prop1>
  </properties>

  <dependencies>
    <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>${log4j.version}</version>
        </dependency>
  </dependencies>

  <build>
    <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>properties-maven-plugin</artifactId>
                <version>1.0-alpha-2</version>
                <executions>
                    <execution>
                        <phase>initialize</phase>
                        <goals>
                            <goal>read-project-properties</goal>
                        </goals>
                        <configuration>
                            <files>
                                <file>${basedir}/my.properties</file>
                            </files>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    <pluginManagement>
        <plugins>
            <!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
            <plugin>
                <groupId>org.eclipse.m2e</groupId>
                <artifactId>lifecycle-mapping</artifactId>
                <version>1.0.0</version>
                <configuration>
                    <lifecycleMappingMetadata>
                        <pluginExecutions>
                            <pluginExecution>
                                <pluginExecutionFilter>
                                    <groupId>
                                        org.codehaus.mojo
                                    </groupId>
                                    <artifactId>
                                        properties-maven-plugin
                                    </artifactId>
                                    <versionRange>
                                        [1.0-alpha-2,)
                                    </versionRange>
                                    <goals>
                                        <goal>
                                            read-project-properties
                                        </goal>
                                    </goals>
                                </pluginExecutionFilter>
                                <action>
                                    <ignore></ignore>
                                </action>
                            </pluginExecution>
                        </pluginExecutions>
                    </lifecycleMappingMetadata>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>
  </build>
</project>

If I run mvn compile, or mvn install the result is:

[ERROR] The build could not read 1 project -> [Help 1]
org.apache.maven.project.ProjectBuildingException: Some problems were encountered while processing the POMs:
[ERROR] 'dependencies.dependency.version' for org.apache.logging.log4j:log4j-api:jar must be a valid version but is   '${log4j.version}'. @ line 16, column 13

The "my.properties" file contains this:

 log4j.version=2.2    

As it described here: mojohaus

If I use the prop1 property, which is defined in the pom.xml, everything is working.

So what I'm doing wrong?

Answer 1

Official answer from them is that using read-project-properties for setting version of dependencies is not supported: https://github.com/mojohaus/properties-maven-plugin/issues/26

This does not work nor is it the intention of properties maven plugin and furthermore what would be the advantage to read properties from a file to define versions of dependencies?

There is a very through explanation about this issue on this answer: https://stackoverflow.com/a/14727072/1707491

Answer 2

Make sure that you have ${basedir}/my.properties file present with that specific property value pair: my.properties contents should be: prop1=2.3

Answer 3

You have to define the version properties when you want to use them. The plugin just allows you to do so; but you will have to set the values for yourself. Like

<properties>
    <log4j.version>1.2.17</log4j.version>
</properties>

EDIT:

As you showed, you have done that. Now it seems, that as you defined the goal within an execution, it is only valid within that execution. Try to declare it as global:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>properties-maven-plugin</artifactId>
    <version>1.0-alpha-2</version>
    <configuration>
        <files>
            <file>${basedir}/my.properties</file>
        </files>
    </configuration>
...

Answer 4

The maven way is to use the element in a top level POM that includes the projects with common dependencies. That is the simplest approach.

You can also import a POM used expressly for dependency managment. The import approach does not require the parent/child project relationships.

See the Maven documentation:

1. Dependency Management
2. Importing Dependencies