Is there a way to invoke an Action without sending a request? - scala

Question

I have a Play2 app which serves some api.
I that same app, I added code that runs an etl based on Alpakka. Under the etl hood, there is a Future[Done] running that never ends. Currently I trigger the etl process with a web request at a separate route.
To deploy my etl service, I wanna be able to run my Play2 app with a special command that ideally does not open a server, but just runs that single Action of etl controller. If it's not achievable and sever has to be open, I'd like to trigger that etl process but isolate my etl box from incoming web connection. I feel that all of this is very hackish and probably there is a better way.

Answer 1

The way I ended up doing it is with scheduled tasks.
A task may be scheduled once and depending on a config variable:
class ProtonConnector #Inject()(
config: TypeSafeConfig,
)(
implicit actorSystem: ActorSystem
) {
// Run the stream
def listen: Future[Done] =
itemsProtonSource.via(mapFlow).via(solrIndexFlow).runWith(Sink.ignore)
// Schedule ETL execution
if (config.scheduleProtonEtlTask) {
actorSystem.scheduler.scheduleOnce(delay = 1.seconds) {
logger.debug("Executing proton ETL task...")
val _ = listen
}
}
}
Then we pick up config.scheduleProtonEtlTask from an environment variable (which has value set to true so the code block inside if would execute).
Then in our CI/CD pipeline we define a new deployment where this env variable would be supplied by task configuration. That deployment may be isolated from outer world too - that way, Play2 still spins up a server but it's inaccessible from outside of local network.