Reference Jar within main Jar to pass as javaagent to JVM

Question

I need to add a -javaagent argument in my JVM args when running jar1, but reference jar2 that is contained within jar1. I have tried:

-javaagent:BOOT-INF/lib/jetty-alpn-agent-2.0.0.jar"

with no success. How do I determine the location of JARs within a running system at runtime?

(This is to run jetty-alpn-agent-2.0.0.jar as a Java Agent for HTTP/2 use with Pushy APNs)

Did you ever find solution to this question? – indusBull May 30 '18 at 18:41 — indusBull, May 30 '18 at 18:41

score 0 · Answer 1 · answered Aug 17 '17 at 07:10

If you know that the class is on the class path, you can typically do:

URL jar = MainClass.class.getProtectionDomain().getCodeSource().getLocation();

The Javaagent is always loaded on the class path which is why you should be able to reference the main class of the regular application.

score 0 · Accepted Answer · answered Jan 02 '19 at 14:37

@indusBull

The solution that worked for me was to define a property called libDirectory in my gradle.properties file, which was the location of where the JARs are located in a running system, and then reference that variable from my Dockerfile:

gradle.properties

libDirectory = /opt/meanwhileinhell/app/lib

Dockerfile

ENTRYPOINT  ["java",\
            ...
            ...
            "-javaagent:${libDirectory}/jetty-alpn-agent.jar",\
            "-jar", "/app.jar"]

Reference Jar within main Jar to pass as javaagent to JVM

2 Answers2