I am developing a Java agent using ByteBuddy, and I need the ByteBuddy library .jar file to be included in the agent .jar file. So far, in order for the agent to run smoothly, I need the ByteBuddy library .jar files to be present in the classpath both at compile time and at runtime. How can I bundle a .jar file such that the agent is self-contained ?
I tried using the shade plugin (as demonstrated here) as well as a few other techniques found on the web, but none of them seem to really include the dependencies in the .jar file, only a reference.
For every technique, I looked in the resulting .jar file (weighs around 5kB every time) and only found the .class files corresponding to the classes I had written, no class files related to ByteBuddy. To be clear, the ByteBuddy library .jar file weighs about 3MB, so I expect my self-contained agent .jar file to weigh around 3MB, as my code is light.
Below is my pom.xml file :
<?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>
<groupId>com.captainhook.agent</groupId>
<artifactId>agent</artifactId>
<version>1.0-SNAPSHOT</version>
<name>agent</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>bytebuddy</artifactId>
<version>1.12.3</version>
<scope>system</scope>
<systemPath>${project.basedir}/byte-buddy-1.12.3.jar</systemPath>
</dependency>
<dependency>
<groupId>net.bytebuddy.agent</groupId>
<artifactId>bytebuddy-agent</artifactId>
<version>1.12.3</version>
<scope>system</scope>
<systemPath>${project.basedir}/byte-buddy-agent-1.12.3.jar</systemPath>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
</project>
And this is the output I get after running mvn package :
[...] [INFO] [INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ agent --- [INFO] [INFO] --- maven-assembly-plugin:2.2-beta-5:single (default) @ agent --- [INFO] Building jar: /home/bluesheet/svn/stages/captainhook/2021/ijp-frida-jdi-bytebuddy/1/dbg/shared/agent/maven-test/agent/target/agent-1.0-SNAPSHOT-jar-with-dependencies.jar [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 1.339 s [INFO] Finished at: 2021-12-31T12:26:59+01:00 [INFO] ------------------------------------------------------------------------
EDIT: So, the reason why all the previous techniques were not working was because of the way I specified the dependencies. This doesn’t get included :
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>bytebuddy</artifactId>
<version>1.12.3</version>
<scope>system</scope>
<systemPath>${project.basedir}/byte-buddy-1.12.3.jar</systemPath>
</dependency>
while this does :
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy</artifactId>
<version>1.12.6</version>
</dependency>
I am new to maven so I blindly copy-pasted a piece of code to include the dependencies and I did not spot the error… Thank you very much !
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Answer
Sounds like you need to use the “maven-assembly-plugin” with the “jar-with-dependencies” descriptor.
E.g. here is a full example pom file with a dependency on ByteBuddy:
<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>test.example</groupId>
<artifactId>packaging-example</artifactId>
<version>1.0-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.4.1</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>test.example.TestByteBuddy</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>net.bytebuddy</groupId>
<artifactId>byte-buddy</artifactId>
<version>1.12.6</version>
</dependency>
</dependencies>
</project>
And for the sake of completeness – here is the main class also :
package test.example;
import net.bytebuddy.ByteBuddy;
public class TestByteBuddy
{
public static void main(String... args) throws Exception
{
System.out.println("Hello Byte Buddy Class - " + ByteBuddy.class);
}
}
Building this will produce an additional file in the target directory – packaging-example-1.0-SNAPSHOT-jar-with-dependencies.jar
Then you should be able to run it simply with :
java -jar packaging-example-1.0-SNAPSHOT-jar-with-dependencies.jar
to give you the output:
Hello Byte Buddy Class - class net.bytebuddy.ByteBuddy