Kubernetes Service Discovery Custom Settings (#313)

* - Added configNamespace in Kubernetes settings object, so that users can create different settings based on config path
- Added "Settings" object to KubernetesApiServiceDiscovery constructor so that users are able to provide their different settings for discovery

* - Added defaultConfig as fallback to user provided config

discovery-kubernetes-api/src/main/scala/org/apache/pekko/discovery/kubernetes/KubernetesApiServiceDiscovery.scala

@@ -96,13 +96,14 @@ object KubernetesApiServiceDiscovery {
  * An alternative implementation that uses the Kubernetes API. The main advantage of this method is that it allows
  * you to define readiness/health checks that don't affect the bootstrap mechanism.
  */
-class KubernetesApiServiceDiscovery(implicit system: ActorSystem) extends ServiceDiscovery {
+class KubernetesApiServiceDiscovery(settings: Settings)(
+    implicit system: ActorSystem) extends ServiceDiscovery {
 
   import system.dispatcher
 
   private val http = Http()
 
-  private val settings = Settings(system)
+  def this()(implicit system: ActorSystem) = this(Settings(system))
 
   private val log = Logging(system, getClass)(LogSource.fromClass)
 

discovery-kubernetes-api/src/main/scala/org/apache/pekko/discovery/kubernetes/Settings.scala

@@ -20,7 +20,9 @@ import com.typesafe.config.Config
 
 import org.apache.pekko.util.OptionConverters._
 
-final class Settings(system: ExtendedActorSystem) extends Extension {
+final class Settings(kubernetesApi: Config) extends Extension {
+
+  def this(system: ExtendedActorSystem) = this(system.settings.config.getConfig("pekko.discovery.kubernetes-api"))
 
   /**
    * Copied from PekkoManagementSettings, which we don't depend on.
@@ -35,8 +37,6 @@ final class Settings(system: ExtendedActorSystem) extends Extension {
       if (hasDefined(key)) Some(config.getString(key)) else None
   }
 
-  private val kubernetesApi = system.settings.config.getConfig("pekko.discovery.kubernetes-api")
-
   val apiCaPath: String =
     kubernetesApi.getString("api-ca-path")