Activating a Child Profile from a Parent Profile - maven

Question

I have the following parent pom.xml file:
<profile>
<id>build_full</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
<modules>
<module>mymodule_interface</module>
<module>mymodule_switch</module>
<module>mymodule_switch_simulator</module>
<module>mymodule_switch_controller</module>
<module>mymodule_server</module>
</modules>
</profile>
and in my child pom for mymodule_server, I have the following:
<profile>
<id>subprofile</id>
<modules>
<module>...various modules...</module>
</modules>
</profile>
<profile>
<id>default</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
<modules>
<module>...various modules...</module>
</modules>
</profile>
How, when I invoke maven: mvn -P build_full, can I force the child module (mymodule_server) to use profile subprofile rather than default?

Answer 1

No, you can't activate a child profile from a parent profile. More generally, you can't activate or deactivate any profile from any other profile (there is a JIRA feature-request MNG-3309). What you can do is activate two profiles based on the same property.
First of all, using a profile that is activated by default is generally not a good idea. What you want is to activate a profile based on some condition (OS version, system property...). To solve your problem, you can activate build_full profile when a certain system property is present, and make sure that subprofile is also activated when that same property is present.
A sample configuration would be the following, where both profiles are activated when the fullBuild system property is set to true. Invoking Maven with mvn -DfullBuild=true ... will thus activate both profiles.
<profile>
<id>build_full</id>
<activation>
<property>
<name>fullBuild</name>
<value>true</value>
</property>
</activation>
<modules>
<module>mymodule_interface</module>
<module>mymodule_switch</module>
<module>mymodule_switch_simulator</module>
<module>mymodule_switch_controller</module>
<module>mymodule_server</module>
</modules>
</profile>
<profile>
<id>subprofile</id>
<activation>
<property>
<name>fullBuild</name>
<value>true</value>
</property>
</activation>
<modules>
<module>...various modules...</module>
</modules>
</profile>

Answer 2

In your case, from the top parent/aggregator folder, you could just run:
mvn clean install -Pbuild_full,!default,subprofile
It will disable any profile having name default (and hence disable the profile in the concerned sub-module) and enable any profile having name subprofile (and hence enable the profile you wanted).
Alternatively, you could configure subprofile as such:
<profiles>
<profile>
<id>subprofile</id>
<activation>
<property>
<name>subprofile</name>
<value>true</value>
</property>
</activation>
....
and then run as following:
mvn clean install -Dsubprofile=true -Pbuild_full
It will have the same effect. You can even avoid the value element and simply specify -Dsubprofile, its existence would be enough to activate the profile (in that case a more meaningful name is suggested, like -DactivateSubprofile). Since you active a different profile, automatically Maven will deactivate the default one.