Skip a submodule during a Maven build

Question

We have a need to be able to skip a submodule in certain environments.

The module in question contains integration tests and takes half an hour to run. So we want t

Answer 1

Sure, this can be done using profiles. You can do something like the following in your parent pom.xml.

  ...
   <modules>
      <module>module1</module>
      <module>module2</module>  
      ...
  </modules>
  ...
  <profiles>
     <profile>
       <id>ci</id>
          <modules>
            <module>module1</module>
            <module>module2</module>
            ...
            <module>module-integration-test</module>
          </modules> 
      </profile>
  </profiles>
 ...

In your CI, you would run maven with the ci profile, i.e. mvn -P ci clean install

Answer 2

It's possible to decide which reactor projects to build by specifying the -pl command line argument:

$ mvn --help
[...]
 -pl,--projects <arg>                   Build specified reactor projects
                                        instead of all projects
[...]

It accepts a comma separated list of parameters in one of the following forms:

• relative path of the folder containing the POM
• [groupId]:artifactId

Thus, given the following structure:

project-root [com.mycorp:parent]
  |
  + --- server [com.mycorp:server]
  |       |
  |       + --- orm [com.mycorp.server:orm]
  |
  + --- client [com.mycorp:client]

You can specify the following command line:

mvn -pl .,server,:client,com.mycorp.server:orm clean install

to build everything. Remove elements in the list to build only the modules you please.

---

EDIT: as blackbuild pointed out, as of Maven 3.2.1 you have a new -el flag that excludes projects from the reactor, similarly to what -pl does:

Answer 3

there is now (from 1.1.1 version) a 'skip' flag in pit.

So you can do things like :

    <profile>
        <id>pit</id>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.pitest</groupId>
                    <artifactId>pitest-maven</artifactId>
                    <configuration>
                        <skip>true</skip>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </profile>

in your module, and pit will skip

[INFO] --- pitest-maven:1.1.3:mutationCoverage (default-cli) @ module-selenium --- [INFO] Skipping project

Answer 4

Maven version 3.2.1 added this feature, you can use the -pl switch (shortcut for --projects list) with ! or - (source) to exclude certain submodules.

mvn -pl '!submodule-to-exclude' install
mvn -pl -submodule-to-exclude install

Be careful in bash the character ! is a special character, so you either have to single quote it (like I did) or escape it with the backslash character.

The syntax to exclude multiple module is the same as the inclusion

mvn -pl '!submodule1,!submodule2' install
mvn -pl -submodule1,-submodule2 install

EDIT Windows does not seem to like the single quotes, but it is necessary in bash ; in Windows, use double quotes (thanks @awilkinson)

mvn -pl "!submodule1,!submodule2" install

Answer 5

The notion of multi-module projects is there to service the needs of codependent segments of a project. Such a client depends on the services which in turn depends on say EJBs or data-access routines. You could group your continuous integration (CI) tests in this manner. I would rationalize that by saying that the CI tests need to be in lock-step with application logic changes.

Suppose your project is structured as:

project-root
  |
  + --- ci
  |
  + --- client
  |
  + --- server

The project-root/pom.xml defines modules

<modules>
  <module>ci</module>
  <module>client</module>
  <module>server</module>
</modules>

The ci/pom.xml defines profiles such as:

... 
<profiles>
  <profile>
    <id>default</id>
    <activation>
      <activeByDefault>true</activeByDefault>
    </activation>
    <plugin>
       <artifactId>maven-surefire-plugin</artifactId>
       <configuration>
         <skip>true</skip>
       </configuration>
     </plugin>
  </profile>
  <profile>
    <id>CI</id>
    <plugin>
       <artifactId>maven-surefire-plugin</artifactId>
       <configuration>
         <skip>false</skip>
       </configuration>
     </plugin>
  </profile>
</profiles>

This will result in Maven skipping tests in this module except when the profile named CI is active. Your CI server must be instructed to execute mvn clean package -P CI. The Maven web site has an in-depth explanation of the profiling mechanism.