Shrink Akka with Proguard using Maven

Question

I am trying to package application that uses Akka, but I receive a well known error message:

[INFO] trouble writing output: Too many method references: 80536; max is 65536.
[INFO] You may try using --multi-dex option.

I found a proguard configuration that should shrink Akka library: https://bitbucket.org/mackler/safe-metronome/src/16f880347863f560d025016ece19d586fbb9874d/project/proguard.cfg?at=default

I set up my Maven build to use similar configuration, but it does not seem that this Akka library is shrinked. As far as I understand to apply proguard on project dependencies it is necessary to make a single jar with all dependencies and than feed it joined jar to proguard.

Here is my Maven config:

<dependencies>
        <dependency>
            <groupId>com.google.android</groupId>
            <artifactId>android</artifactId>
            <version>4.1.1.4</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-actor_2.10</artifactId>
            <version>2.4-SNAPSHOT</version>
        </dependency>
    </dependencies>

    <build>
        <sourceDirectory>src</sourceDirectory>
        <finalName>${project.artifactId}</finalName>

        <plugins>
            <plugin>
                <groupId>com.jayway.maven.plugins.android.generation2</groupId>
                <artifactId>android-maven-plugin</artifactId>
                <version>3.7.0</version>
                <extensions>true</extensions>
                <configuration>
                    <sdk>
                        <platform>16</platform>
                    </sdk>
                </configuration>
            </plugin>

            <plugin>
                  <artifactId>maven-assembly-plugin</artifactId>
                  <configuration>
                      <descriptorRefs>
                          <descriptorRef>jar-with-dependencies</descriptorRef>
                      </descriptorRefs>
                  </configuration>
                  <executions>
                      <execution>
                          <id>make-assembly</id>
                          <phase>package</phase>
                          <goals>
                              <goal>assembly</goal>
                          </goals>
                      </execution>
                  </executions>
              </plugin>
            <plugin>
                <groupId>com.github.wvengen</groupId>
                <artifactId>proguard-maven-plugin</artifactId>
                <version>2.0.6</version>
                <dependencies>
                    <dependency>
                        <groupId>net.sf.proguard</groupId>
                        <artifactId>proguard-base</artifactId>
                        <version>4.9</version>
                        <scope>runtime</scope>
                    </dependency>
                </dependencies>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>proguard</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <libs>
                        <lib>${java.home}/lib/rt.jar</lib>
                    </libs>
                    <obfuscate>false</obfuscate>
                    <options>
                        <option>@proguard.cfg</option>
                    </options>
                </configuration>
            </plugin>

        </plugins>
    </build>

What am I doing wrong?

P.S. dex tool is suggesting to use '--multi-dex' option, but I didn't find how to add it with Maven android plugin. Is there any workaround?

Answer 1

Here is the configuration that worked after all:

<build>
    <sourceDirectory>src</sourceDirectory>

    <plugins>
        <plugin>
            <groupId>com.jayway.maven.plugins.android.generation2</groupId>
            <artifactId>android-maven-plugin</artifactId>
            <configuration>                 
                <manifest>
                    <debuggable>true</debuggable>
                </manifest>
                <proguard>
                    <config>proguard.cfg</config>
                    <skip>false</skip>
                </proguard>
                <sdk>
                    <platform>16</platform>
                </sdk>
                <test>
                    <skip>true</skip>
                </test>
                <undeployBeforeDeploy>true</undeployBeforeDeploy>
            </configuration>
            <extensions>true</extensions>
        </plugin>
    </plugins>
</build>

Answer 2

Answer to a slightly modified version of the question "Shrink Akka with Proguard using SBT"

Would be to use the Proguard SBT plugin. Here's an example of shrinking Akka with it. on GitHub.