What is a Parent POM and Why do we need one for Mule?

byGonzalo Marcos -


A parent POM (Project Object Model) in Maven is a pom.xml file that acts as a template or baseline configuration for other Maven projects. It defines common settings, dependencies, plugins, and configurations that can be shared across multiple Maven projects. In Mulesoft, a parent POM will help us to centrally manage all the common configurations and dependencies (connectors, plugins, libraries) that our Mule applications should have.

Why do we need a Parent POM for Mule?

What problems are we trying to solve with a Parent POM in Mule? Is it worth using it? Here are three good reasons:

Centralized Configuration Management:

In large projects with multiple Mule applications or APIs, each project often requires the same set of configurations, such as:
  • Common dependencies (e.g., Mule runtime dependencies, Connectors, shared libraries).
  • Plugin configurations (e.g., Mule Maven Plugin settings).
  • Repository definitions - All of our Mule apps will use, at least, Exchange and the Mulesoft Public repositories
Without a parent POM, we would have to manually configure these settings in each individual pom.xml file, leading to duplication and increased maintenance effort.

A parent POM centralizes these configurations, reducing redundancy and making it easier to maintain consistent settings across multiple projects.

Reduced Boilerplate Code:

Instead of duplicating Maven configuration in every Mule project, a parent POM eliminates boilerplate XML in the child pom.xml files. This makes the child pom.xml files simpler and more focused on application-specific configurations rather than general settings.

For example, most of our APIs (if not all) will include the HTTP connector, the Sockets connector, the APIKit router or the Secure Properties module. With all of these dependencies defined in the parent POM, we won’t have to add them in the POM file of each application. We’d only be adding those connectors/dependencies used specifically in our app.

Consistency Across Environments:

In our Mule deployment, each application typically requires environment-specific configurations (e.g., for connecting to Anypoint Platform, databases, or external systems). These settings can be centralized in the parent POM, allowing each child project to inherit these settings, reducing configuration errors, and maintaining environment consistency.

For example, if we used the Mule Maven Plugin to publish and deploy the app to Cloudhub/Runtime Fabric/On Prem we would have to include the deployment parameters on each app’s POM. With a parent POM, we only define it once for all child projects and we can make sure all of our apps follow the same build and deployment practices.


What exactly is a Parent POM? How does it work?

A parent POM (Project Object Model) in Maven is a pom.xml file that acts as a template or baseline configuration for other Maven projects. We create a parent POM the same way we would create the POM file of a specific app. The difference is that in the parent POM would define settings, dependencies, plugins, and configurations that can be shared across multiple Maven projects. Any element in the POM of our apps that is redundant/common to all the apps is something that we can move to a parent POM

Then, for each individual mule app using the parent POM, we only need to reference the parent POM from which it inherits. With that all the elements in the parent POM will be incorporated to the effective POM of our app. The beauty of this is that we won’t see all of the common elements in the child POMs, which will reduce and make much more clean our individual app’s POMs.


What Goes Into a Parent POM?

Let’s now see what common elements of our Mule apps we could include into a parent POM. A parent POM typically includes the following sections:

1. General Project Information

This section defines the project’s general information, which child mule projects can inherit.

<groupId>com.example</groupId>
<artifactId>parent-pom</artifactId>
<version>1.0.0</version>
<packaging>pom</packaging>
  • groupId: The unique identifier for the project (e.g., organization or company). In Mulesoft, this is our Org Id or Business Group Id
  • artifactId: The ID of the project’s artifact, typically the name of our mule app.
  • version: The version of the parent POM.
  • packaging: Must be pom for a parent POM. This is how Maven will know that this is not a Mule app but a parent POM.

2. Dependency Management

The <dependencyManagement> section is used to define dependency versions that child projects can inherit without having to specify versions explicitly in their own POMs. 
Although this would be useful for our Parent POM, this section would make more sense to be included into a BOM file. But there might be cases in which it makes sense to put this section in the parent POM.
If you want to know more about the BOM file have a look at this couple of previous posts:

<project>
    ...
    <dependencyManagement>
        <dependencies>
            ...
            <dependency>
                <groupId>org.mule.connectors</groupId>
                <artifactId>mule-http-connector</artifactId>
                <version>1.9.1</version>
                <classifier>mule-plugin</classifier>
            </dependency>
            <dependency>
                <groupId>org.mule.connectors</groupId>
                <artifactId>mule-sockets-connector</artifactId>
                <version>1.2.4</version>
                <classifier>mule-plugin</classifier>
            </dependency>
            ...
        </dependencies>
    </dependencyManagement>
    ...
</project>


3. Plugin Management

Similarly to the dependencyManagement section, we can include a pluginManagement section to define the versions of all common plugins in our Mule apps. This way, our child mule projects won’t have to specify versions for the plugins. But again, this is something more suitable for a BOM file. An example:

<project>
    ...
    <build>
        <pluginManagement>
            <plugins>
                ...
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.2.0</version>
                </plugin>
                <plugin>
                    <groupId>org.mule.tools.maven</groupId>
                    <artifactId>mule-maven-plugin</artifactId>
                    <version>4.1.0</version>
                    <extensions>true</extensions>
                    <configuration>
                        <classifier>mule-plugin</classifier>
                    </configuration>
                </plugin>
                ...
            </plugins>
        </pluginManagement>
    </build>
    ...
</project>


4. Build Plugins

Plugins are used to customize the build process. In the parent POM, you can configure plugins that are common to all child projects. For example, all of our Mule projects will include these two plugins:

<project>
    ...
    <build>
        <plugins>
            ...
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-clean-plugin</artifactId>
                <version>3.2.0</version>
            </plugin>
            <plugin>
                <groupId>org.mule.tools.maven</groupId>
                <artifactId>mule-maven-plugin</artifactId>
                <version>4.1.0</version>
                <extensions>true</extensions>
            </plugin>
            ...
        </plugins>
    </build>
    ...
</project>


5. Properties

We can define properties in the parent POM to centralize configuration values of all of our Mule apps. Some examples would be runtime version, anypoint credentials, deployment settings... that are used throughout all the child mule projects.

<project>
    ...
    <properties>
        ...
        <mule.runtime.version>4.6.0</mule.runtime.version>
        <anypoint.username>${env.ANYPOINT_USERNAME}</anypoint.username>
        <anypoint.password>${env.ANYPOINT_PASSWORD}</anypoint.password>
        <cloudhub.workers>2</cloudhub.workers>
        <cloudhub.worker.type>Micro</cloudhub.worker.type>
        <cloudhub.region>us-east-1</cloudhub.region>
        ...
    </properties>
    ...
</project>


If you want to know what values or parameters we could include as maven properties in our Mule apps, check out this other post where you will find 10 Maven Properties you should include in your Mule Apps


6. Repositories

We can define external repositories in the parent POM, which will be inherited by all child mule projects. In this section, for example, we could include our Anypoint Exchange as a common repository for all of our apps

<project>
    ...
    <repositories>
        ...
        <repository>
            <id>anypoint-exchange-v3</id>
            <name>Anypoint Exchange</name>
            <url>https://maven.anypoint.mulesoft.com/api/v3/maven</url>
            <layout>default</layout>
        </repository>
        ...
    </repositories>
    ...
</project>


7. Plugin Repositories

Similar to repositories, we can define common repositories for the plugins that our child mule projects can inherit. For example, the Mulesoft Public repository is a good candidate, as it is included by default in all of our mule apps with Anypoint Studio.

<project>
    ...
    <pluginRepositories>
        <pluginRepository>
            <id>mulesoft-releases</id>
            <name>MuleSoft Releases Repository</name>
            <layout>default</layout>
            <url>https://repository.mulesoft.org/releases/</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>
    ...
</project>


8. Profiles

We can define profiles in the parent POM to allow child mule projects to inherit profile-specific build configurations (e.g., different settings for development, testing, or production environments). Profiles defined in the parent POM allow child projects to activate specific configurations depending on the environment.

<profiles>
    <profile>
        <id>production</id>
        <properties>
            <env>prod</env>
        </properties>
    </profile>
</profiles>


That’s a quick summary of why we should use a parent POM for our Mule apps and what we could include in our parent POM. In the next post, we’ll see How to define a parent POM for our Mule apps with a practical example.

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