How to set a JVM argument progarammatically in Ballerina

Question

I am trying to set a JVM argument programmetically in a Ballerina server. I was able to set up the enviroment variable in the terminal but unable to do so, programmatically.

I am trying to set up the jdk.tls.namedGroups enviromment variable with a Ballerina sample server, but the named groups did not change in the TLS handshake.

import ballerina/http;
import ballerina/os;


os:Error? err = os:setEnv("_JAVA_OPTIONS", "-Djdk.tls.namedGroups=secp256r1,secp384r1,secp521r1");


listener http:Listener securedEP = new (9090,
    secureSocket = {
        key: {
            certFile: "./serverpubliccert.crt",
            keyFile: "./serverpvtkey.key"
        },
        protocol: {
            name: "TLS",
            versions: ["TLSv1.3"]
        }
    }
);

service / on securedEP {
    resource function get greeting(string name) returns string|error {
        // Send a response back to the caller.
        if name is "" {
            return error("name should not be empty!");
        }
        return "Hello, " + name;
    }
}

When I tried setting the environment variable in the terminal, it worked.

export _JAVA_OPTIONS="-Djdk.tls.namedGroups=secp256r1,secp384r1,secp521r1" 

Answer 1

AFAIK, _JAVA_OPTIONS env variable is pickedup by JVM itself. Because of that it needs to be there before the JVM started. When you set it inside a ballerina program, the jvm is already started, I'm guessing the Java behavior also is the same.

Is there are any problem with setting the _JAVA_OPTIONS env variable using the terminal for your usecase?