Maven: How to include ${project.version} in multi-module project

Question

I am using maven 3.2.1

 mvn -version
Apache Maven 3.2.1 (ea8b2b07643dbb1b84b6d16e1f08391b666bc1e9; 2014-02-14T09:37:52-08:00)
Maven home: /usr/local/Cellar/maven/3.2.1/libexec
Java version: 1.7.0_55, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.7.0_55.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.9.2", arch: "x86_64", family: "mac"

My module structure

projectA/
        pom.xml
        core/
             pom.xml
             business/
                     pom.xml
             persistence/
                     pom.xml
             rest/
                     pom.xml
       federated_services/
                     pom.xml

ProjectA/pom.xml

    <groupId>com.org</groupId>
    <artifactId>projectA</artifactId>
    <packaging>pom</packaging>
    <version>${global.version}</version>
    <properties>
        <global.version>1.0-SNAPSHOT</global.version>
    </properties>

core/pom.xml

<parent>
    <artifactId>projectA</artifactId>
    <groupId>com.org</groupId>
    <version>${global.version}</version>
    <relativePath>..</relativePath>
</parent>

Things are fine until here meaning core/xml can find ${project.version}. But when I do

persistence/pom.xml

   <parent>
        <artifactId>core</artifactId>
        <groupId>com.org</groupId>
        <version>${global.version}</version>
        <relativePath>../../</relativePath>
    </parent>

The pom complains

[ERROR]   The project com.org:persistence:${global.version} (/Users/harith/IdeaProjects/project/core/persistence/pom.xml) has 1 error
[ERROR]     Non-resolvable parent POM: Could not transfer artifact com.org:core:pom:${global.version} from/to local central mirror (http://maven.corp.org.com:9999/repository/public): Illegal character in path at index 68: http://maven.corp.org.com:9999/repository/public/com/org/core/${global.version}/core-${global.version}.pom and 'parent.relativePath' points at wrong local POM @ line 5, column 13 -> [Help 2]

Question
- How can I have persistence/pom.xml inherit ${project.version} from projectA/pom.xml?

Solution 1

Generally speaking, just don't include a version in the child; it'll inherit it. If you have to specify a version (Roo is notorious for throwing tantrums with valid POMs it doesn't approve of), you can either specify the parent version with the property or use ${project.parent.version} for the child's version. Also look at the versions plugin, which will set the version on a whole hierarchy at once.

Solution 2

First in general you can't use properties in versions:

ProjectA/pom.xml

  <groupId>com.org</groupId>
  <artifactId>projectA</artifactId>
  <packaging>pom</packaging>
  <version>1.0.0-SNAPSHOT</version>

Second you shouldn't need to use relative path in your childs: core/pom.xml

<parent>
  <artifactId>projectA</artifactId>
  <groupId>com.org</groupId>
  <version>1.0.0-SNAPSHOT</version>
</parent>
<artifactId>core</artifactId>

This brings me to the point if you have a persistence/pom.xml

core com.org 1.0.0-SNAPSHOT

Done use things like <relativePath>../../</relativePath> this is usually an indicator that your structure is wrong.

BUT: Starting with Maven 3.2.1 you can use special properties to define the versions you like. The following placeholders are allowed in versions:

${revision}, ${changelist}, and ${sha1}

This means if you like you can use them but only with Maven 3.2.1 so you need to change it to things like this:

ProjectA/pom.xml

  <groupId>com.org</groupId>
  <artifactId>projectA</artifactId>
  <packaging>pom</packaging>
  <version>${revision}</version>

and in core:

<parent>
  <artifactId>projectA</artifactId>
  <groupId>com.org</groupId>
  <version>${revision}</version>
</parent>
<artifactId>core</artifactId>

But this means you need to call maven everytime like this:

mvn -Drevision=1.0.0-SNAPSHOT clean package

which will work. You have to be carefull if you use your project within Eclipse etc. Apart from the above i can not recommend to use it this way.