Log the launch command for Spark daemons

For debugging and analysis purposes, it's nice to have the exact command
used to launch Spark contained within the logs. This adds the necessary
hooks to make that possible.

bin/spark-daemon.sh

@@ -75,6 +75,8 @@ if [ "$SPARK_IDENT_STRING" = "" ]; then
   export SPARK_IDENT_STRING="$USER"
 fi
 
+export SPARK_PRINT_LAUNCH_COMMAND="1"
+
 # get log directory
 if [ "$SPARK_LOG_DIR" = "" ]; then
   export SPARK_LOG_DIR="$SPARK_HOME/logs"
@@ -124,8 +126,9 @@ case $startStop in
 
     spark_rotate_log $log
     echo starting $command, logging to $log
+    echo "Spark Daemon: $command" > $log
     cd "$SPARK_PREFIX"
-    nohup nice -n $SPARK_NICENESS "$SPARK_PREFIX"/run $command "$@" > "$log" 2>&1 < /dev/null &
+    nohup nice -n $SPARK_NICENESS "$SPARK_PREFIX"/run $command "$@" >> "$log" 2>&1 < /dev/null &
     echo $! > $pid
     sleep 1; head "$log"
     ;;

run

@@ -164,4 +164,12 @@ else
   # The JVM doesn't read JAVA_OPTS by default so we need to pass it in
   EXTRA_ARGS="$JAVA_OPTS"
 fi
-exec "$RUNNER" -cp "$CLASSPATH" $EXTRA_ARGS "$@"
+
+command="$RUNNER -cp \"$CLASSPATH\" $EXTRA_ARGS $@"
+if [ "$SPARK_PRINT_LAUNCH_COMMAND" == "1" ]; then
+  echo "Spark Command: $command"
+  echo "======================================"
+  echo
+fi
+
+exec $command