Minimize an Uber Jar correctly, Using Shade-Plugin

Question

I am using the Maven-Shade-Plugin to create a runnable Uber-jar. According to the last frame on this page, the size of the jar can be minimized by using:

<configuration>
      <minimizeJar>true</minimizeJar>
</configuration>

But this feature does not take into consideration the classes that are declared in the log4j.properties file. Hence, e.g. org.apache.log4j.appender.TimeAndSizeRollingAppender is not included in the Uber-jar, even though it’s declared in the log4j.properties file.

I believe I will face the same problem with Spring. If my code only refers to interface A and my Spring file contains an instantiation of class B that implements A, then B might not be added to the jar, since it’s not in the code.

How can I solve this problem?

Answer 1

This functionality has been added to version 1.6 of the maven-shade-plugin (just released). minimizeJar will now not remove classes that have been specifically included with filters. Note that including some of an artifact's classes in a filter will exclude non-specified classes for that artifact, so be sure to include all the classes that you need.

Here's an example plugin config:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>1.6</version>    
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>                        
            <configuration>
                <minimizeJar>true</minimizeJar>    
                <filters> 
                    <filter>
                       <artifact>log4j:log4j</artifact>
                       <includes>
                           <include>**</include>
                       </includes>
                    </filter> 
                    <filter>
                       <artifact>commons-logging:commons-logging</artifact>
                       <includes>
                           <include>**</include>
                       </includes>
                    </filter>                      
                </filters>
            </configuration>
        </execution>
    </executions>
</plugin>

To only include specific classes, add them as includes using path slashes in the class name in a filter (again, non-included classes will be automatically excluded).

<filter>
  <artifact>org.yourorg:your-artifact</artifact>
  <includes>
    <include>org/yourorg/yourartifact/api/*</include>
    <include>org/yourorg/yourartifact/util/*</include>
  </includes>
</filter>