lib/Rex/CLI.pm: display a warning when/if Rex::Template is loaded.

lib/Rex/CLI.pm

@@ -30,8 +30,6 @@ use Rex::TaskList;
 use Rex::Logger;
 use YAML;
 
-use Data::Dumper;
-
 my $no_color = 0;
 eval "use Term::ANSIColor";
 if ($@) { $no_color = 1; }
@@ -197,6 +195,7 @@ FORCE_SERVER: {
 
   load_server_ini_file($::rexfile);
   load_rexfile($::rexfile);
+  check_template_modules();
 
   #### check if some parameters should be overwritten from the command line
 CHECK_OVERWRITE: {
@@ -455,6 +454,21 @@ sub __help__ {
 
 }
 
+# Check whether Rex/Template.pm
+# or Rex/Template/NG.pm modules are loaded. If there are,
+# they should be present in the %INC hash.
+sub check_template_modules {
+    my @tpl_modules_loaded = grep {
+        /(Rex\/Template|Rex\/Template\/NG)/
+    } keys %INC;
+    if (scalar @tpl_modules_loaded > 0) {
+        Rex::Logger::info( "WARNING! You are using Rex built-in template engine aka Rex::Template.", "warn" );
+        Rex::Logger::info( "This engine is obsolete, unmaintained and will be retired in future releases.", "warn" );
+        Rex::Logger::info( "Please consider migrating to a more modern template engine.", "warn" );
+        Rex::Logger::info( "Text::Template::Simple, Template::Toolkit, etc. As usual, CPAN is you friend.", "warn" );
+    }
+}
+
 sub add_help {
   my ( $self, $code ) = @_;
   push( @help, $code );