docker_memory: add total memory used

plugins/docker/docker_memory

@@ -55,6 +55,7 @@ $docker =~ s/\s+$//;
 
 my @containers = split "\n" , `$docker ps --no-trunc=true`;
 my $result;
+my $total = 0;
 
 for my $i (1 .. $#containers)
 {
@@ -82,6 +83,7 @@ for my $i (1 .. $#containers)
       my $memory_bytes = <$file>;
       $memory_bytes =~ s/\s+$//;
       push @result, {'name'=>$name, 'memory_bytes'=>$memory_bytes};
+      $total = $total + $memory_bytes;
    }
 }
 
@@ -93,17 +95,26 @@ if (defined $ARGV[0] and $ARGV[0] eq "config")
    print "graph_category virtualization\n";
    print "graph_info This graph shows docker container memory usage.\n";
 
+   my $first = 1;
    foreach(@result)
    {
       print "$$_{'name'}.label $$_{'name'}\n";
-      print "$$_{'name'}.draw LINE2\n";
+      if ($first) {
+      	print "$$_{'name'}.draw AREA\n";
+	$first = 0
+      } else {
+	print "$$_{'name'}.draw STACK\n";
+      }
    }
+   print "total.label Total Memory\n";
+   print "total.draw LINE2\n";
    exit 0;
 }
 
 foreach(@result)
 {
    print "$$_{'name'}.value $$_{'memory_bytes'}\n";
 }
+print "total.value $total\n";
 
 # vim:syntax=perl