How to fix compression error when repackaging Spring Boot Jar

Question

I need to inject static UI files into an existing Spring Boot executable jar. To do so, I'm pulling the jar as a dependency, and using the maven antrun plugin to:

• Unzip the jar in a temp dir

• Add a resources dir to the unzipped jar

• Copy static UI files to the resources dir

• Re-zip the jar

   <plugin>
     <artifactId>maven-assembly-plugin</artifactId>
     <version>3.1.0</version>
     <executions>
       <execution>
         <id>build-ui-kit</id>
         <phase>package</phase>
         <goals>
           <goal>single</goal>
         </goals>
         <configuration>
           <descriptors>
             <descriptor>ui-assembly-config.xml</descriptor>
           </descriptors>
         </configuration>
       </execution>
     </executions>
   </plugin>
  
   <plugin>
     <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-antrun-plugin</artifactId>
     <version>1.6</version>
     <executions>
       <execution>
         <id>repack</id>
         <phase>compile</phase>
         <goals>
           <goal>run</goal>
         </goals>
         <configuration>
           <target>
             <!-- unzip jar -->
             <unzip src="${com.xxx:xxx:jar}" dest="${project.build.directory}/tmp"/>
             <!-- make resources dir in unzipped jar dir -->
             <mkdir dir="${project.build.directory}/tmp/resources"/>
             <!-- copy ui files to resources dir -->
             <copy todir="${project.build.directory}/tmp/resources">
               <fileset dir="${basedir}/../../src/ui/dist">
                 <include name="*"/>
               </fileset>
             </copy>
             <!-- zip tmp dir to create txapps jar  -->
             <zip basedir="${project.build.directory}/tmp" destfile="${project.build.directory}/yyyy.jar"/>
           </target>
         </configuration>
       </execution>
     </executions>
   </plugin>
  

This all seems to work; however, when I run the Jar, I get the following error:

Caused by: java.lang.IllegalStateException: Unable to open nested entry 'BOOT-INF/lib/HdrHistogram-2.1.12.jar'. It has been compressed and nested jar files must be stored without compression. Please check the mechanism used to create your executable jar file

When I inspect the contents of the Jar, everything looks fine (the libs do not seem to be compressed). Any idea of what's going on here or suggestions for a better repackaging solution? Thanks!

Answer 1

I ended up using the exec-maven-plugin and Java jar utility to add the UI files. See code below (the ui files are in the /tmp/resources directory):

<plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>exec-maven-plugin</artifactId>
      <version>3.0.0</version>
      <executions>
        <execution>
          <id>update-jar</id>
          <phase>package</phase>
          <goals>
            <goal>exec</goal>
          </goals>
        </execution>
      </executions>
      <configuration>
        <executable>jar</executable>
        <workingDirectory>${project.build.directory}/tmp</workingDirectory>
        <arguments>
          <argument>uf</argument>
          <argument>dependencies/myjar-${version}.jar</argument>
          <argument>resources</argument>
        </arguments>
      </configuration>
    </plugin>