Bdtjtk

I've been trying to find an answer to this issue in similar questions but I still don't know what is causing it.

I have a multi-module maven project and I'm trying to run mvn install or mvn package and I get the following error

[INFO] app ................................................... SUCCESS
[ 1.025 s]

[INFO] module-data ..................................... FAILURE [
0.952 s]

[INFO] module-app ...................................... SKIPPED

[ERROR] Failed to execute goal
org.springframework.boot:spring-boot-maven-plugin:2.1.1.RELEASE:repackage
(repackage) on project project-data: Execution repackage of goal
org.springframework.boot:spring-boot-maven-plugin:2.1.1.RELEASE:repackage
failed: Unable to find main class -> [Help 1]

The project-app module has a java class in the src folder, whereas the project-data module does not have a main class.

parent pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <packaging>pom</packaging>

    <modules>

        <module>project-data</module>

        <module>project-app</module>

    </modules>

    <parent>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-parent</artifactId>

        <version>2.1.1.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.example</groupId>

    <artifactId>app</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>app</name>

    <description></description>



    <properties>

        <java.version>1.8</java.version>

    </properties>



    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-data-jpa</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-jdbc</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-thymeleaf</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>



        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-devtools</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>com.h2database</groupId>

            <artifactId>h2</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <optional>true</optional>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

    </dependencies>



    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>



</project>

project-data pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <parent>

        <artifactId>app</artifactId>

        <groupId>com.example</groupId>

        <version>0.0.1-SNAPSHOT</version>

    </parent>

    <modelVersion>4.0.0</modelVersion>



    <artifactId>project-data</artifactId>



    <dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-data-jpa</artifactId>

        </dependency>

        <dependency>

            <groupId>com.h2database</groupId>

            <artifactId>h2</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>org.postgresql</groupId>

            <artifactId>postgresql</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <optional>true</optional>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

    </dependencies>

    <build>

        <plugins>

            <plugin>

                <groupId>org.springframework.boot</groupId>

                <artifactId>spring-boot-maven-plugin</artifactId>

                <executions>

                    <execution>

                        <goals>

                            <goal>repackage</goal>

                        </goals>

                        <configuration>

                            <skip>true</skip>

                        </configuration>

                    </execution>

                </executions>

            </plugin>

        </plugins>

    </build>

</project>

project-app pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <parent>

        <artifactId>app</artifactId>

        <groupId>com.example</groupId>

        <version>0.0.1-SNAPSHOT</version>

    </parent>

    <modelVersion>4.0.0</modelVersion>



    <artifactId>project-app</artifactId>



    <dependencies>

        <dependency>

            <artifactId>project-data</artifactId>

            <groupId>com.example</groupId>

            <version>0.0.1-SNAPSHOT</version>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-actuator</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-thymeleaf</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-web</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-devtools</artifactId>

            <scope>runtime</scope>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

    </dependencies>





</project>

I have something very similar to the structure of this project (sfg-pet-clinic), however, after downloading and running mvn package, it works fine. I don't see much difference between the pom files of my project and this one so what could I be missing?

I would move the entire

<build>

    <plugins>

        <plugin>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-maven-plugin</artifactId>

        </plugin>

    </plugins>

</build>

section from the parent to the module-app module, because that one is the single module which uses the repackage functionality.

Moreower I would delete the plugin section from the module-data too, because there is no need to repackage that module.

Thanks to @wemu on the comments section.

Adding this:

<configuration>

    <mainClass> ${your.start.Class}</mainClass>

</configuration>

to the plugin section is required on version 2.1.1.RELEASE of the spring-boot-starter-parent dependency, as long as your class is in another module.

The project sfg-pet-clinic I referred to in my question uses an older version which does not need the <mainClass> configuration

Okay here is how I fixed that.

My Steps were:

1. Change the packaging of pom.xml file for project-data to pom from
   jar (I used overview of Eclipse)


2. add <type>pom</type> in pom.xml file for project-app for dependency of module-data

        <dependency>

            <groupId>samee.springframework</groupId>

            <artifactId>project-data</artifactId>

            <version>0.0.1-SNAPSHOT</version>

             <type>pom</type>

        </dependency>  

Then you can run your clean and package/install

I just changed the Spring Boot version in the parent pom.xml from 2.1.1 to 2.0.3 and it works.

<parent>

    <groupId>org.springframework.boot</groupId>

    <artifactId>spring-boot-starter-parent</artifactId>

    <version>2.0.3.RELEASE</version>

    <relativePath /> <!-- lookup parent from repository -->

</parent>

Would be better to make it work in 2.1.1 though, but that's a quick and simple solution.