moved configuration validation to a separate function. Declared an Application.configureApplication extension to validate the configs at the start.

src/main/kotlin/net/ipksindia/Application.kt

@@ -2,13 +2,14 @@ package net.ipksindia
 
 import io.ktor.server.application.*
 import io.ktor.server.netty.*
-import net.ipksindia.config.AppConfig
-import net.ipksindia.plugins.*
+import net.ipksindia.config.configureApplication
+import net.ipksindia.plugins.configureRouting
+import net.ipksindia.plugins.configureSerialization
 
 fun main(args: Array<String>):Unit = EngineMain.main(args)
 
 fun Application.module() {
-    AppConfig.validateConfig()
+    configureApplication()
     configureSerialization()
     configureRouting()
 }

src/main/kotlin/net/ipksindia/config/AppConfig.kt

@@ -1,54 +1,19 @@
 package net.ipksindia.config
 
+import com.typesafe.config.Config
 import com.typesafe.config.ConfigFactory
+import net.ipksindia.config.AppConfig.config
 import org.slf4j.LoggerFactory
 import kotlin.system.exitProcess
 
 object AppConfig {
 
-    private val logger = LoggerFactory.getLogger(AppConfig::class.java)
-
     private val environment = ConfigFactory.load().getString("ktor.environment")
-    private val config = when (environment) {
+    val config: Config = when (environment) {
         "prod" -> ConfigFactory.load("application-prod.conf")
         else -> ConfigFactory.load("application-dev.conf")
     }
 
-    fun validateConfig() {
-        val requiredKeys = listOf(
-            "database.host",
-            "database.port",
-            "database.name",
-            "database.user",
-            "database.password",
-            "bank.server.protocol",
-            "bank.server.host",
-            "bank.server.port",
-            "bank.server.rootRoute",
-            "bank.server.transactionRoute",
-            "bank.codes"
-        )
-
-        val missingKeys = requiredKeys.filterNot { config.hasPath(it) }
-
-        if (missingKeys.isNotEmpty()) {
-            logger.error("Missing configuration keys: {}", missingKeys.toString())
-            exitProcess(1)
-        }
-
-        val dbPort = config.getInt("database.port")
-        val remoteServerPort = config.getInt("bank.server.port")
-        if (dbPort !in 1..65535) {
-            logger.error("Invalid database port: {}", dbPort)
-            exitProcess(1)
-        }
-
-        if (remoteServerPort !in 1..65535) {
-            logger.error("Invalid remote server port: {}", remoteServerPort)
-            exitProcess(1)
-        }
-    }
-
     val databaseConfig by lazy { DatabaseConfig(
         config.getString("database.host"),
         config.getInt("database.port"),
@@ -88,4 +53,40 @@ data class DatabaseConfig(
     val password: String
 ) {
     val url = "jdbc:oracle:thin:@$host:$port:$name"
+}
+
+fun validateAppConfigs() {
+    val logger = LoggerFactory.getLogger(AppConfig::class.java)
+    val requiredKeys = listOf(
+        "database.host",
+        "database.port",
+        "database.name",
+        "database.user",
+        "database.password",
+        "bank.server.protocol",
+        "bank.server.host",
+        "bank.server.port",
+        "bank.server.rootRoute",
+        "bank.server.transactionRoute",
+        "bank.codes"
+    )
+
+    val missingKeys = requiredKeys.filterNot { config.hasPath(it) }
+
+    if (missingKeys.isNotEmpty()) {
+        logger.error("Missing configuration keys: {}", missingKeys.toString())
+        exitProcess(1)
+    }
+
+    val dbPort = config.getInt("database.port")
+    val remoteServerPort = config.getInt("bank.server.port")
+    if (dbPort !in 1..65535) {
+        logger.error("Invalid database port: {}", dbPort)
+        exitProcess(1)
+    }
+
+    if (remoteServerPort !in 1..65535) {
+        logger.error("Invalid remote server port: {}", remoteServerPort)
+        exitProcess(1)
+    }
 }

src/main/kotlin/net/ipksindia/config/Configuration.kt

@@ -0,0 +1,8 @@
+package net.ipksindia.config
+
+import io.ktor.server.application.*
+
+
+fun Application.configureApplication() {
+    validateAppConfigs()
+}