Spring Boot Maven Plugin - No BOOT-INF directory

Question

Between version 1.3.8.RELEASE of the spring-boot-maven-plugin and version 1.4.0.RELEASE - there has been a change in the generated package structure (if you extract the uber jar file) 1.3.8.RELEASE com, lib, META-INF and org directories 1.4.0.RELEASE has a BOOT-INF, META-INF and org directories Basically from 1.4.0.RELEASE onwards - all the classes and libs are in the BOOT-INF directory. Due to this - when you try to run a Spring Boot project on Amazon Lambda - it says that there is a jar not found as it cannot read the new Spring Boot Uber jar structure

My question is - is it possible in the newer versions of the Spring Boot Maven Plugin to get it to generate the uber jar to be the same structure as in version 1.3.9.RELEASE?

I tried the maven-shade-plugin - but that leads to other issues

Any help is greatly appreciated

Thanks Damien

Answer 1

The solution was to add the MODULE layout for the plugin in the pom.xml file

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <layout>MODULE</layout>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Answer 2

The answer above with

<layout>MODULE</layout>

does not work anymore, this is because layout element is deprecated in Spring Boot 2.x. I am using Spring Boot 2.0.x, I found this helpful comment on github:

Support for the module layout was removed in Spring Boot 2.0 having been deprecated in 1.5. Unfortunately, the updates to the Maven Plugin's documentation were missed so we can use this issue to sort that out. You should use a custom LayoutFactory instead.

But as I did not want to implement LayoutFactory I tried this second solution below that actually repackage and creates an extra jar with a classifier given name:

This is due to the change in layout of executable jars in Spring Boot 1.4. Application classes are now packaging in BOOT-INF/classes. Your client module depends on the repackaged, fat jar of your web module. Due to the new layout that means that the client module can no longer load the web module's classes. If you want to use your web module as a dependency, you should configure Boot's repackaging to apply a classifier to the fat jar. For example:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                    <configuration>
                        <classifier>exec</classifier>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Doing so will allow other modules to depend on the original jar that does not embed the module's dependencies and has the classes at the root of the jar.

One original jar have the same structure as I wanted like

com.my-package.foo.bar
META-INF

and the second classifier have the newer structure with BOOT-INF/ etc.

Answer 3

For me, the solution was a bit more insidious....I had the spring-boot-maven-plugin nested under pluginManagement, (see below). Doh!

The nasty thing, is that when I'd run mvn spring-boot:run, spring boot comes up just fine, and runs app! It wasn't until we tried to deploy to PCF (as a spring-boot JAR), that we'd get an error that there was something wrong with format of the binary....

<build>

  <!-- 
    DON'T DO THIS!! 
  -->
  <pluginManagement>

    <plugins>             
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>${spring.boot.version}</version>            
        <executions>
            <execution>
                <goals>
                    <goal>repackage</goal>
                    <goal>build-info</goal>
                </goals>
            </execution>
        </executions>                        
      </plugin>                                     
    </plugins>

  </pluginManagement>

  <!-- 
    DO THIS INSTEAD!! 
  -->      
<plugins>

    <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
      <version>${spring.boot.version}</version>            
      <executions>
          <execution>
              <goals>
                  <goal>repackage</goal>
                  <goal>build-info</goal>
              </goals>
          </execution>
      </executions>                        
    </plugin>                         

  </plugins>

</build>

Once I removed the pluginManagement tags from the POM, I would now get the ./BOOT-INF structure. Please keep in mind that pluginManagement is typically for a parent-pom structure, where you want that plugin's config used across other modules.