$npx -y skills add rrezartprebreza/spring-boot-skills --skill multi-module-mavenUse when working in a multi-module Maven project. Covers parent POM conventions, shared dependency management, inter-module rules, and build ordering.
| 1 | # Multi-Module Maven |
| 2 | |
| 3 | ## Typical Structure |
| 4 | |
| 5 | ``` |
| 6 | my-app/ |
| 7 | ├── pom.xml ← Parent POM (packaging = pom) |
| 8 | ├── my-app-domain/ ← Pure Java domain — no Spring |
| 9 | │ └── pom.xml |
| 10 | ├── my-app-application/ ← Use cases — depends on domain |
| 11 | │ └── pom.xml |
| 12 | ├── my-app-infrastructure/ ← JPA, Redis, HTTP clients |
| 13 | │ └── pom.xml |
| 14 | └── my-app-web/ ← Spring Boot app, REST — depends on all above |
| 15 | └── pom.xml |
| 16 | ``` |
| 17 | |
| 18 | ## Parent POM |
| 19 | |
| 20 | ```xml |
| 21 | <!-- pom.xml (parent) --> |
| 22 | <project> |
| 23 | <groupId>com.example</groupId> |
| 24 | <artifactId>my-app</artifactId> |
| 25 | <version>1.0.0-SNAPSHOT</version> |
| 26 | <packaging>pom</packaging> |
| 27 | |
| 28 | <modules> |
| 29 | <module>my-app-domain</module> |
| 30 | <module>my-app-application</module> |
| 31 | <module>my-app-infrastructure</module> |
| 32 | <module>my-app-web</module> |
| 33 | </modules> |
| 34 | |
| 35 | <parent> |
| 36 | <groupId>org.springframework.boot</groupId> |
| 37 | <artifactId>spring-boot-starter-parent</artifactId> |
| 38 | <version>3.3.0</version> |
| 39 | </parent> |
| 40 | |
| 41 | <!-- Shared versions — all modules inherit --> |
| 42 | <properties> |
| 43 | <java.version>21</java.version> |
| 44 | <mapstruct.version>1.6.0</mapstruct.version> |
| 45 | <testcontainers.version>1.19.8</testcontainers.version> |
| 46 | </properties> |
| 47 | |
| 48 | <!-- Dependency management — centralizes versions, NOT adding to classpath --> |
| 49 | <dependencyManagement> |
| 50 | <dependencies> |
| 51 | <!-- Inter-module dependencies --> |
| 52 | <dependency> |
| 53 | <groupId>com.example</groupId> |
| 54 | <artifactId>my-app-domain</artifactId> |
| 55 | <version>${project.version}</version> |
| 56 | </dependency> |
| 57 | <dependency> |
| 58 | <groupId>com.example</groupId> |
| 59 | <artifactId>my-app-application</artifactId> |
| 60 | <version>${project.version}</version> |
| 61 | </dependency> |
| 62 | <!-- Third-party versions --> |
| 63 | <dependency> |
| 64 | <groupId>org.mapstruct</groupId> |
| 65 | <artifactId>mapstruct</artifactId> |
| 66 | <version>${mapstruct.version}</version> |
| 67 | </dependency> |
| 68 | </dependencies> |
| 69 | </dependencyManagement> |
| 70 | |
| 71 | <!-- Shared plugins --> |
| 72 | <build> |
| 73 | <pluginManagement> |
| 74 | <plugins> |
| 75 | <plugin> |
| 76 | <groupId>org.apache.maven.plugins</groupId> |
| 77 | <artifactId>maven-compiler-plugin</artifactId> |
| 78 | <configuration> |
| 79 | <source>${java.version}</source> |
| 80 | <target>${java.version}</target> |
| 81 | <annotationProcessorPaths> |
| 82 | <path> |
| 83 | <groupId>org.projectlombok</groupId> |
| 84 | <artifactId>lombok</artifactId> |
| 85 | </path> |
| 86 | <path> |
| 87 | <groupId>org.mapstruct</groupId> |
| 88 | <artifactId>mapstruct-processor</artifactId> |
| 89 | <version>${mapstruct.version}</version> |
| 90 | </path> |
| 91 | </annotationProcessorPaths> |
| 92 | </configuration> |
| 93 | </plugin> |
| 94 | </plugins> |
| 95 | </pluginManagement> |
| 96 | </build> |
| 97 | </project> |
| 98 | ``` |
| 99 | |
| 100 | ## Child Module POM (domain — no Spring) |
| 101 | |
| 102 | ```xml |
| 103 | <project> |
| 104 | <parent> |
| 105 | <groupId>com.example</groupId> |
| 106 | <artifactId>my-app</artifactId> |
| 107 | <version>1.0.0-SNAPSHOT</version> |
| 108 | </parent> |
| 109 | |
| 110 | <artifactId>my-app-domain</artifactId> |
| 111 | |
| 112 | <dependencies> |
| 113 | <!-- No Spring. No JPA. Pure Java only. --> |
| 114 | <dependency> |
| 115 | <groupId>org.projectlombok</groupId> |
| 116 | <artifactId>lombok</artifactId> |
| 117 | <optional>true</optional> |
| 118 | </dependency> |
| 119 | </dependencies> |
| 120 | </project> |
| 121 | ``` |
| 122 | |
| 123 | ## Child Module POM (web — the runnable app) |
| 124 | |
| 125 | ```xml |
| 126 | <project> |
| 127 | <parent>...</parent> |
| 128 | <artifactId>my-app-web</artifactId> |
| 129 | |
| 130 | <dependencies> |
| 131 | <dependency> |
| 132 | <groupId>com.example</groupId> |
| 133 | <artifactId>my-app-application</artifactId> |
| 134 | </dependency> |
| 135 | <dependency> |
| 136 | <groupId>com.example</groupId> |
| 137 | <artifactId>my-app-infrastructure</artifactId> |
| 138 | </dependency> |
| 139 | <dependency> |
| 140 | <groupId>org.springframework.boot</groupId> |
| 141 | <artifactId>spring-boot-starter-web</artifactId> |
| 142 | </dependency> |
| 143 | </dependencies> |
| 144 | |
| 145 | <build> |
| 146 | <plugins> |
| 147 | <!-- Only in the runnable module, not parent --> |
| 148 | <plugin> |
| 149 | <groupId>org.springframework.boot</groupId> |
| 150 | <artifactId>spring-boot-maven-plugin</artifactId> |
| 151 | </plugin> |
| 152 | </plugins> |
| 153 | </build> |
| 154 | </project> |
| 155 | ``` |
| 156 | |
| 157 | ## Dependency Rules |
| 158 | |
| 159 | | Module | Can depend on | Cannot dep |