How to identify and set a missing environment property in Maven?

Question

I have my build set-up so that I pass in my variable via the command line:

mvn clean install -DsomeVariable=data

In my pom I have:

<someTag>${someVariable}</someTag>

This works fine, but I would like to identify if someVariable is not specified on the command line, and then default it so that my script can continue.

Can this be done in Maven?

score 14 · Accepted Answer · answered Nov 07 '11 at 22:25

You can specify default property value in the properties section of your POM file:

<properties>
  <someVariable>myVariable</someVariable>
</properties>

If you want to make sure that the property value is ALWAYS supplied on a command line, then you can use maven-enforcer-plugin.

Here is a link that shows how to enforce system property presence -> http://maven.apache.org/enforcer/enforcer-rules/requireProperty.html

I'll just copy the XML verbatim here in case the above link goes bad.

<project>
  [...]
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-enforcer-plugin</artifactId>
        <version>1.0.1</version>
        <executions>
          <execution>
            <id>enforce-property</id>
            <goals>
              <goal>enforce</goal>
            </goals>
            <configuration>
              <rules>
                <requireProperty>
                  <property>basedir</property>
                  <message>You must have a basedir!</message>
                  <regex>\d</regex>
                  <regexMessage>You must have a digit in your baseDir!</regexMessage>
                </requireProperty>
                <requireProperty>
                  <property>project.version</property>
                  <message>"Project version must be specified."</message>
                  <regex>(\d|-SNAPSHOT)$</regex>
                  <regexMessage>"Project version must end in a number or -SNAPSHOT."</regexMessage>
                </requireProperty>
              </rules>
              <fail>true</fail>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  [...]
</project>

Thank-you for the insightful response Alex. Though I am looking to default the property rather than enforce it. So if it is not specified then the script would use the default value. — TERACytE, Nov 07 '11 at 22:53
@TERACytE. Yes, a value in `properties` section is a default, and you can always overwrite it from command line. — Alexander Pogrebnyak, Nov 08 '11 at 03:41

score 8 · Answer 2 · edited Jan 05 '17 at 19:56

8

You can specify the default value as

<properties>
      <someTag>defaultValue</someTag>
</properties>

When you run maven command, you can override that value like this

mvn clean package -DsomeTag=newSpecificValue

edited Jan 05 '17 at 19:56

Kai

700
7
33

answered Jun 27 '14 at 16:33

Arnab

154
2
6

SImple solution i needed to use in a Jenkins build – pdem Sep 07 '15 at 14:09

score 2 · Answer 3 · answered Jan 19 '12 at 23:18

You can use profiles instead, but you'll need a profile for each variable.

 <profile>
    <id>default-value-1</id>
    <activation>
          <activeByDefault>false</activeByDefault>
          <property>
             <name>!someVariable</name>
          </property>
    </activation>
    <properties>
        <someVariable>DEFAULT-VALUE</someVariable>
    </properties>
</profile>

How to identify and set a missing environment property in Maven?

3 Answers3

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