Allow Application to Exit without Shutting Down the Process

[sklose]

Cookie Cutter has a mechanism to detect if an application is hanging and won't shutdown gracefully. That is done with a simple timer that kills the process if the process hasn't exited by itself already. This mechanism can get in the way if a service wants to stop and restart its application without exiting the process. An example for that could be hot-reloading of configuration changes without rescheduling the pod in Kubernetes.

We should make this behavior configurable via the application behavior that is passed into the run function.

import { Application, ConsoleLogger, sleep } from "@walmartlabs/cookie-cutter-core";
import { intervalSource } from "@walmartlabs/cookie-cutter-timer";

class Output { }

const handler = {
    onInterval: (msg, ctx) => {
      ctx.publish(Output, { ...msg });
    }
  };
const app = () => Application.create()
  .logger(new ConsoleLogger())
  .input()
  .add(
    intervalSource({
      timeout: 1000,
    })
  )
  .done()
  .dispatch(handler)
  .run();

// this only works with this hack, which makes
// the CC application believe it's in test mode
// (global as any).it = () => { };

async function main() {
  for (let i=0; i<10; i++) {
    console.log("starting app");
    const a = app();
    await sleep(1000);
    a.cancel();
    await a;
  }
}

main();