!! NOTICE Empty java init template

[earthling-amzn]

Please add your +1 👍 to let us know you have encountered this

Status: IN-PROGRESS

Overview:

A recent change to the init templates caused the application emitted by default java init template to not instantiate the stack class correctly. This results in cdk synth emitting an empty template.

Complete Error Message:

No error emitted, result is an empty stack.

Workaround:

Change the call to the builder of the generated stack to a call to the class constructor instead.

example:
change

MyAppStack.Builder.create(app, "MyAppStack")
                .build();

to

new MyAppStack(app, "MyAppStack")

Solution:

Remove the attempted usage of the nested builder classes in the init template output and replace with call to stack constructor.

Related Issues:

Original Issue

After running cdk init --language java, the generated App doesn't use the generated Stack.

Reproduction Steps

$ mkdir cdk-init-broken && cd cdk-init-broken
$ cdk init --language java
# Setup a stack in CdkInitBrokenStack.java
$ cdk synth
# Stack is empty

What did you expect to happen?

Expected my stack to be rendered into cloud formation templates.

What actually happened?

Generated an empty stack.

Environment

• CDK CLI Version : 1.96.0
• Framework Version: 1.96.0
• Node.js Version: v10.19.0
• OS : Ubuntu 20.04
• Language (Version): Java

Other

Replaced generated App code with code from examples and it worked great:

public class CdkInitBrokenApp {
    public static void main(final String[] args) {
        App app = new App();

        new CdkInitBrokenStack(app, "CdkInitBrokenStack");

        app.synth();
    }
}

---

This is 🐛 Bug Report

[NetaNir]

executing cdk init -l java creates the below main:

    public static void main(final String[] args) {
        App app = new App();

        JavainitStack.Builder.create(app, "JavainitStack").build(); // stack 
        app.synth();
    }

Can you try again?

[earthling-amzn]

That's similar to the code I see generated for the App (less a few comments). The trouble is, that code doesn't actually invoke the constructor of the generated JavainitStack, so you end up with an empty Cfn template.

public class JavainitStack extends Stack {
    public JavainitStack(final Construct scope, final String id) {
        this(scope, id, null);
    }

    public JavainitStack(final Construct scope, final String id, final StackProps props) {
        super(scope, id, props);
        // This code from the lambda cron example in aws-cdk-examples is never called.
        SingletonFunction lambdaFunction =
          SingletonFunction.Builder.create(this, "cdk-lambda-cron")
            .description("Lambda which prints \"I'm running\"")
            .code(Code.fromInline("def main(event, context):\n" + "    print(\"I'm running!\")\n"))
            .handler("index.main")
            .timeout(Duration.seconds(300))
            .runtime(Runtime.PYTHON_2_7)
            .uuid(UUID.randomUUID().toString())
            .build();

        Rule rule =
          Rule.Builder.create(this, "cdk-lambda-cron-rule")
            .description("Run every day at 6PM UTC")
            .schedule(Schedule.expression("cron(0 18 ? * MON-FRI *)"))
            .build();

       rule.addTarget(new LambdaFunction(lambdaFunction));
    }
}

[NetaNir]

Thanks @earthling-amzn! You are right, a change to our java init template is the culprit, we are on it!
Related: b940710