Moved check to SparkContext.

Author: zzvara

core/src/main/scala/org/apache/spark/SparkConf.scala

@@ -449,14 +449,6 @@ class SparkConf(loadDefaults: Boolean) extends Cloneable with Logging {
       }
     }
 
-    // System property spark.yarn.app.id must be set if user code ran by AM on a YARN cluster
-    // yarn-standalone is deprecated, but still supported
-    if ((get("spark.master") == "yarn-cluster" || get("spark.master") == "yarn-standalone") &&
-      get("spark.yarn.app.id", null) == null) {
-      throw new SparkException("Detected yarn-cluster mode, but isn't running on a cluster. " +
-        "Deployment to YARN is not supported directly by SparkContext. Please use spark-submit.")
-    }
-
   }
 
   /**

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -371,6 +371,14 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
       throw new SparkException("An application name must be set in your configuration")
     }
 
+    // System property spark.yarn.app.id must be set if user code ran by AM on a YARN cluster
+    // yarn-standalone is deprecated, but still supported
+    if ((master == "yarn-cluster" || master == "yarn-standalone") &&
+        !_conf.contains("spark.yarn.app.id")) {
+      throw new SparkException("Detected yarn-cluster mode, but isn't running on a cluster. " +
+        "Deployment to YARN is not supported directly by SparkContext. Please use spark-submit.")
+    }
+
     if (_conf.getBoolean("spark.logConf", false)) {
       logInfo("Spark configuration:\n" + _conf.toDebugString)
     }