Multi Module Maven

rrezartprebreza/multi-module-maven

> Use when working in a multi-module Maven project. Covers parent POM conventions, shared dependency management, inter-module rules, and build ordering.

4k tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

190

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/rrezartprebreza/spring-boot-skills --skill multi-module-maven

The instruction itself

7 sections, as written by the author

Multi-Module Maven

Typical Structure

my-app/
├── pom.xml                  ← Parent POM (packaging = pom)
├── my-app-domain/           ← Pure Java domain — no Spring
│   └── pom.xml
├── my-app-application/      ← Use cases — depends on domain
│   └── pom.xml
├── my-app-infrastructure/   ← JPA, Redis, HTTP clients
│   └── pom.xml
└── my-app-web/              ← Spring Boot app, REST — depends on all above
    └── pom.xml

Parent POM

<!-- pom.xml (parent) -->
<project>
    <groupId>com.example</groupId>
    <artifactId>my-app</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>pom</packaging>

    <modules>
        <module>my-app-domain</module>
        <module>my-app-application</module>
        <module>my-app-infrastructure</module>
        <module>my-app-web</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.3.0</version>
    </parent>

    <!-- Shared versions — all modules inherit -->
    <properties>
        <java.version>21</java.version>
        <mapstruct.version>1.6.0</mapstruct.version>
        <testcontainers.version>1.19.8</testcontainers.version>
    </properties>

    <!-- Dependency management — centralizes versions, NOT adding to classpath -->
    <dependencyManagement>
        <dependencies>
            <!-- Inter-module dependencies -->
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>my-app-domain</artifactId>
                <version>${project.version}</version>
            </dependency>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>my-app-application</artifactId>
                <version>${project.version}</version>
            </dependency>
            <!-- Third-party versions -->
            <dependency>
                <groupId>org.mapstruct</groupId>
                <artifactId>mapstruct</artifactId>
                <version>${mapstruct.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <!-- Shared plugins -->
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>${java.version}</source>
                        <target>${java.version}</target>
                        <annotationProcessorPaths>
                            <path>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                            </path>
                            <path>
                                <groupId>org.mapstruct</groupId>
                                <artifactId>mapstruct-processor</artifactId>
                                <version>${mapstruct.version}</version>
                            </path>
                        </annotationProcessorPaths>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

Child Module POM (domain — no Spring)

<project>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>my-app</artifactId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>

    <artifactId>my-app-domain</artifactId>

    <dependencies>
        <!-- No Spring. No JPA. Pure Java only. -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>
</project>

Child Module POM (web — the runnable app)

<project>
    <parent>...</parent>
    <artifactId>my-app-web</artifactId>

    <dependencies>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>my-app-application</artifactId>
        </dependency>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>my-app-infrastructure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- Only in the runnable module, not parent -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Dependency Rules

| Module | Can depend on | Cannot depend on |

|--------|---------------|------------------|

| domain | Nothing | Everything |

| application | domain | infrastructure, web |

| infrastructure | domain, application | web |

| web | All modules | — |

Gotchas

Agent puts spring-boot-maven-plugin in parent POM — only in the runnable module
Agent adds <dependencies> in parent instead of <dependencyManagement> — adds to all modules' classpath
Agent creates circular dependencies between modules — enforce the dependency direction above
Agent imports Spring in domain module — domain must be framework-free
Agent uses ${project.version} for inter-module versions — correct, but update parent version to update all

How to use it

Copy the folder

Take rrezartprebreza/multi-module-maven from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.