How to execute AWS lambda with Open JDK 11+ as custom runtime?

Question

AWS allows to create Lambda function with Java 8 (OpenJDK 8) as runtime. I need to create a simple function using Open JDK 11. Something like that:

package example;

import com.amazonaws.services.lambda.runtime.Context; 
import com.amazonaws.services.lambda.runtime.LambdaLogger;

public class Hello {
    public String myHandler(int myCount, Context context) {
        LambdaLogger logger = context.getLogger();
        logger.log("received : " + myCount);
        return String.valueOf(myCount);
    }
}

There is an option allowing to use a custom runtime and a tutorial that contains an example with Shell. However there is no example with Java.

Is anyone have already deal with an AWS lambda with custom java runtime?

Answer 1

I was also curious as to why we haven't seen any custom runtimes for Java yet, so about a month ago I started playing around with the idea of building one in Java 11 using Jigsaw to produce small runtime. While it's not exactly a tutorial, I did write a fairly detailed Readme on how to build this and the code is simple enough to follow.

Here's my project on GitHub:

https://github.com/andthearchitect/aws-lambda-java-runtime

I just published this recently and it's most certainly a POC so use at your own risk.

Corretto seems interesting but I would guess there will still be people out there who are more comfortable with the official OpenJDK release. I'm hoping maybe this can be the starting point for a production ready open source runtime for Java.