Automatically detect criteo IP address for checks

This should remove the constraint on Mesos to configure `criteo` network
in a specific order (last element). With patch, the effective address of
the current task should be assign the criteo network's (first) IP
address (if it is defined), otherwise we will fall back to the previous
heuristic (extract the first IP address provided by Mesos).

JIRA: MESOS-5907

src/main/scala/mesosphere/marathon/core/task/state/NetworkInfo.scala

@@ -28,7 +28,9 @@ case class NetworkInfo(
     */
   def effectiveIpAddress(runSpec: RunSpec): Option[String] = {
     if (!ipAddresses.isEmpty) {
-      pickFirstIpAddressFrom(ipAddresses)
+      findCriteoIpAddress().getOrElse(
+        pickFirstIpAddressFrom(ipAddresses)
+      )
     } else {
       Some(hostName)
     }
@@ -91,6 +93,18 @@ object NetworkInfo extends StrictLogging {
     }
   }
 
+  def findCriteoIpAddress(mesosStatus: mesos.Protos.TaskStatus): Option[mesos.Protos.NetworkInfo.IPAddress] = {
+    if (mesosStatus.hasContainerStatus && mesosStatus.getContainerStatus.getNetworkInfosCount > 0) {
+      mesosStatus.getContainerStatus.getNetworkInfosList
+        .find(_.getName == "criteo")
+        .map(_.getIpAddressesList)
+        .headOption
+        .map(_.getIpAddress)
+    } else {
+      None
+    }
+  }
+
   private def computePortAssignments(
     app: AppDefinition,
     hostName: String,