pass module args as extra variable

[Nick-H]

Hi, 

in order to debug a playbook , I need to pass some value to a module_arg at run time .

I thought using extra-variables but it doesn't work, args still show 'null' 

The module is elasticache and I need to try a run with hard_modify  = true . 

But this is not part as one of the existing variable in my playbook, 

I just need to override at runtime the default value from the module (I am using Tower)

I tried the following: 

elasticache: 

  hard_modify: true 

as well as : 

elasticache.hard_modify: true 

but none worked and the default value is still returned.