these plugins should not be loaded at marathon init time (not lazy).

Summary:
This solution has been tested to work.   I guess that the debate will be:

  # should this be in the PluginModule or in a AppInfoModule or the like

  # should all the plugins be force loaded... I didn't check but several already are in AuthModule, AkkaHttpModule

Test Plan: yet to come

Reviewers: zen-dog, timcharper, ichernetsky, jeschkies, unterstein, jdef, jenkins

Reviewed By: timcharper, ichernetsky, jenkins

Subscribers: marathon-dev

JIRA Issues: MARATHON-7545

Differential Revision: https://phabricator.mesosphere.com/D995

src/main/scala/mesosphere/marathon/core/plugin/PluginModule.scala

@@ -4,11 +4,25 @@ package core.plugin
 import mesosphere.marathon.core.base.CrashStrategy
 import mesosphere.marathon.core.plugin.impl.PluginManagerImpl
 import mesosphere.marathon.plugin.http.HttpRequestHandler
+import mesosphere.marathon.plugin.task.RunSpecTaskProcessor
+import mesosphere.marathon.plugin.validation.RunSpecValidator
 
 class PluginModule(config: MarathonConf, crashStrategy: CrashStrategy) {
 
   lazy val pluginManager: PluginManager = PluginManagerImpl(config, crashStrategy)
 
   lazy val httpRequestHandler: Seq[HttpRequestHandler] = pluginManager.plugins[HttpRequestHandler]
 
+  /**
+    * This list of plugins are eagerly loaded at marathon-init time so that configuration failure
+    * is detected in boot process and Marathon will fail to start.
+    *
+    * It is likely long term to have an opt-in strategy for plugins that wish to have this behavior.
+    */
+  private[this] def initPlugins(): Unit = {
+    pluginManager.plugins[RunSpecTaskProcessor]
+    pluginManager.plugins[RunSpecValidator]
+  }
+
+  initPlugins()
 }