Hi! I have a sever application, which has some mission-critical background tasks. If they are faile...

# ktor

[Pavel Kunyavskiy [JB]]

Hi!

I have a sever application, which has some mission-critical background tasks. If they are failed, the best you can do, is just to stop application. What is good coroutine context to start them? I'm trying to start in Application, but it's a SupervisorJob, so it doesn't propagate failures. I can do something like add an inner scope inside Application with handler doing a System.exit() , but that's looks too rude way to stop. Maybe you have some better way to do that?

[PHondogo]

What about creating outer scope and launch Ktor application along with backend tasks in it?

[simon.vergauwen]

You can launch embeddedServer which runs on a CoroutineScope which is then the parent of Application : SupervisorJob so if you can the outer CoroutineScope it also stop the Application

[simon.vergauwen]

coroutineScope parent@ {
  val engine = embeddedServer(...) {
    // use parent
  }
  // use parent
  // awaitCancellation()
  //engine.start(wait = true)
}

[simon.vergauwen]

runBlocking can be a replacement for coroutineScope here as well depending on where you need to actually launch this code

[Pavel Kunyavskiy [JB]]

Looks good. Can this be done with EngineMain to continue using file-based config?

[simon.vergauwen]

I think if you use EngineMain you lose control over how the server is started, and thus its lifecycle.

Ktor has some support to still rely on file config, but never used it https://ktor.io/docs/configurations.html#embedded-custom

I mostly rely on manual configuration, like this https://github.com/nomisRev/ktor-arrow-example/blob/main/src/main/kotlin/io/github/nomisrev/env/Env.kt

And I've also used the hoplite library, https://github.com/sksamuel/hoplite

[Emil Kantis]

Hoplite is really nice to work with 👍