This gist demonstrates how to pass a complex structure (dict) from one ansible playbook to another via dependency roles. Gist made me use filenames with '_' in place of '/'

called_tasks_main.yml

---
 # Goal: Use the variables defined in caller/tasks/main.yml in these tasks

 # This will fail with an error
 # One or more undefined variables: 'unicode object' has no attribute 'a'
 - debug: msg="{{complex['a']}}"

 # The problem is that passing vars via role dependencies seems to serialize the structure
 # The solution is to de-serialize and capture it into a new variable with some jinja filter magic
 - debug: msg="{{complex | to_json | capture(complicated)}}"

caller_meta_main.yml

---
 dependencies:
   # Unlike python, you can't do complicated=complicated to pass the variable along.
   # This will cause a circular reference error.
   #- { role: called, complex: complicated }

   # So we have to rename the variable and convert back in the called tasks file.
   - { role: called, complex: complicated }

caller_tasks_main.yml

---
 - hosts: all
   vars:
    - complicated: { 'a': 'b', 'c': [{'1':'2'}]}
   tasks:

    - debug: msg="{{complicated['a'] and also complicated.c }}"

project_structure

Imagine this:
```
project-name/
                     roles/
                              caller/
                                       tasks/
                                                main.yml
                                       meta/
                                               main.yml
                              called/
                                       tasks/
                                               main.yml

```