Koin 2.0 Retrofit example

RetrofitClient.kt

import com.github.harmittaa.koinexample.BuildConfig
import okhttp3.OkHttpClient
import org.koin.dsl.module
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

val networkModule = module {
    factory { AuthInterceptor() }
    factory { provideOkHttpClient(get()) }
    factory { provideForecastApi(get()) }
    single { provideRetrofit(get()) }
}

fun provideRetrofit(okHttpClient: OkHttpClient): Retrofit {
    return Retrofit.Builder().baseUrl(BuildConfig.API_URL).client(okHttpClient)
        .addConverterFactory(GsonConverterFactory.create()).build()
}

fun provideOkHttpClient(authInterceptor: AuthInterceptor): OkHttpClient {
    return OkHttpClient().newBuilder().addInterceptor(authInterceptor).build()
}

fun provideForecastApi(retrofit: Retrofit): WeatherForecastApi = retrofit.create(WeatherForecastApi::class.java)

Hi. I think it will be right to use WeatherApi instead of WeatherForecastApi because in your medium post you are created WeatherApi interface.