Compose app and ktor server

[davisoqt]

I have a compose app(not kmp) with a ktor-server running. How do i inject my app module intances to ktor-server implementation?

[Alox1d]

Share the same Koin instance with the embedded server. Registering the same module in a second container would give its single definitions a second set of instances.

With koin-ktor 4.2.2, you can bind the application's existing container to the Ktor Application:

import io.ktor.server.application.Application
import org.koin.core.Koin
import org.koin.ktor.ext.inject
import org.koin.ktor.plugin.setKoin

fun Application.httpApi(appKoin: Koin) {
    setKoin(appKoin)

    val service by inject<MyService>()
    // Configure routes here; their handlers can use service.
}

Pass the container that already owns your Compose application's dependencies when configuring embeddedServer { httpApi(appKoin) }. If you obtain it inside Compose, use org.koin.compose.getKoin(), but let an appropriate application owner manage starting and stopping the server.

Application.getKoin() first reads the application attribute installed by setKoin; it also falls back to an already-started default Koin context. Explicitly passing the container makes this work for an isolated app context as well.

One lifecycle detail matters: in this version, installing the Koin server plugin stops an existing default context for its reload handling, starts its configured context, and closes that context when the server stops. That is a different ownership model from borrowing the desktop/app container.

setKoin only establishes dependency lookup. It does not install the plugin's request-scope hooks or lifecycle events. The example is for sharing app-level services; keep that container alive until the embedded server has stopped. Passing a resolved MyService directly into your server module is another straightforward option if you do not need Ktor's injection extensions.

This is checked against the 4.2.2 implementation, not a run of your Compose/Ktor project.