Specify pom properties via a properties file?

Question

Due to the way my build system is designed (RTC Build Engine), I would like to provide maven with property values via a properties file, instead of specifying -Dkey=value for every property.

I found a couple of questions on S.O. (How to set build properties from a file in Maven POM? and How to read an external properties file in Maven) that relate precisely to this question, but they are relatively old, and both require custom plugins to work (in alpha state).

I realize that passing parameters to Maven like this is probably not the best solution, but the other option is specifying everything on the command line via -D settings which is not ideal either.

Furthermore, given that this properties file is only really used by the build engine (and not by the individual developer), I don't truly believe it belongs in the pom. But I cannot find any other mechanism that would allow me to specify a plugin to use - settings.xml does not permit specifying plugins.

Is my only choice in this case to use a plugin and specify it in the project pom?

Answer 1

in the pom you can place...

<properties>
    <core-version>1234</core-version>
    <lib-version>1234</lib-version>
    <build-version>9999</lib-version>
    <build-date>20150101</build-date>
</properties>

with all the properties you require.

Or you can use...

<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>dev.properties</file>
              </files>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

and the file dev.properties will contain the properties

core-version=1234
lib-version=1234
build-version=9999
build-date=20150101
...

Or... you can inject the properties using a settings.xml file as shown here

You may also find the Maven build number plugin useful... here

Answer 2

The best in such cases is to upgrade to at least Maven 3.2.1 which supports defining such properties on the command line like the following:

mvn -Drevision=1234 -Dchangelist=WhatEver -Dsha1=XXXX clean package

But you can only use the above names.

Excerpt from release notes:

A simple change to prevent Maven from emitting warnings about versions with property expressions. Allowed property expressions in versions include ${revision}, ${changelist}, and ${sha1}. These properties can be set externally, but eventually a mechanism will be created in Maven where these properties can be injected in a standard way. For example you may want to glean the current Git revision and inject that value into ${sha1}. This is by no means a complete solution for continuous delivery but is a step in the right direction.