ansible - jinja filter for dict merging

custom.py

from jinja2.utils import soft_unicode

def merge_dicts(value, dict1):
    # return a merged dict
    result = {}
    result.update(value)
    result.update(dict1)
    return result

class FilterModule(object):
    ''' Ansible jinja2 filters '''

    def filters(self):
        return {
            'merge_dicts': merge_dicts,
        }

output

TASK: [debug var=foo] ********************************************************* 
ok: [centos66] => {
    "var": {
        "foo": {
            "bar": "a string", 
            "fox": "jumpped", 
            "over": "lazy dog"
        }
    }
}

play.yml

---
- hosts: centos66
  remote_user: vagrant
  gather_facts: no
  vars:
    foo:
      bar: 'a string'
  tasks:
    - set_fact:
        foo: "{{ foo | merge_dicts(item) }}"
      with_items:
        - { 'fox': 'jumpped', 'over': 'lazy dog' }

    - debug: var=foo