Maven version with a property

The correct answer is this (example version):

  • In parent pom.xml you should have (not inside properties):

    <version>0.0.1-SNAPSHOT</version>
    
  • In all child modules you should have:

    <parent>
        <groupId>com.vvirlan</groupId>
        <artifactId>grafiti</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    

So it is hardcoded.

Now, to update the version you do this:

mvn versions:set -DnewVersion=0.0.2-SNAPSHOT
mvn versions:commit # Necessary to remove the backup file pom.xml

and all your 400 modules will have the parent version updated.


Using a property for the version generates the following warning:

[WARNING]
[WARNING] Some problems were encountered while building the effective model for xxx.yyy.sandbox:Sandbox:war:0.1.0-SNAPSHOT
[WARNING] 'version' contains an expression but should be a constant. @ xxx.yyy.sandbox:Sandbox:${my.version}, C:\Users\xxx\development\gwtsandbox\pom.xml, line 8, column 14
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]

If your problem is that you have to change the version in multiple places because you are switching versions, then the correct thing to do is to use the Maven Release Plugin that will do this for you automatically.


If you have a parent project you can set the version in the parent pom and in the children you can reference sibling libs with the ${project.version} or ${version} properties.

If you want to avoid to repeat the version of the parent in each children: you can do this:

<modelVersion>4.0.0</modelVersion>
<groupId>company</groupId>
<artifactId>build.parent</artifactId>
<version>${my.version}</version>
<packaging>pom</packaging>

<properties>
<my.version>1.1.2-SNAPSHOT</my.version>
</properties>

And then in your children pom you have to do:

    <parent>
      <artifactId>build.parent</artifactId>
      <groupId>company</groupId>
      <relativePath>../build.parent/pom.xml</relativePath>
      <version>${my.version}</version>
    </parent>

    <modelVersion>4.0.0</modelVersion>
    <groupId>company</groupId>
    <artifactId>artifact</artifactId>
    <packaging>eclipse-plugin</packaging>

    <dependencies>
        <dependency> 
           <groupId>company</groupId>
           <artifactId>otherartifact</artifactId>   
           <version>${my.version}</version>
or
           <version>${project.version}</version>
        </dependency>
    </dependencies>

hth


See the Maven - Users forum 'version' contains an expression but should be a constant. Better way to add a new version?:

here is why this is a bad plan.

the pom that gets deployed will not have the property value resolved, so anyone depending on that pom will pick up the dependency as being the string uninterpolated with the ${ } and much hilarity will ensue in your build process.

in maven 2.1.0 and/or 2.2.0 an attempt was made to deploy poms with resolved properties... this broke more than expected, which is why those two versions are not recommended, 2.2.1 being the recommended 2.x version.