How do I get Jib to run a jar built by Gradle?

Question

I have a simple Gradle project that produces a jar at build/libs/backend-0.0.1-SNAPSHOT.jar. I test this locally like java -jar build/libs/backend-0.0.1-SNAPSHOT.jar. This runs perfect locally. Now I would like to run on my local Docker instance instead of natively. To do this I add the following...

jib {
    from {
        image = 'amazoncorretto:20'
    }
    to {
        image = 'cbusha/be'
    }
}

and run the following

gradle jibDockerBuild
docker run -d -p 8080:8080 cbusha/be

but when I go to docker desktop I see

Exited (0) (25 seconds ago)

and no other information. What is going on and how do I get this to boot up properly?