How do I run an Ansible playbook for 'collections' of CloudFormation stacks?

Question

I am using Ansible to manage numerous CloudFormation stacks all based on the same playbook and CloudFormation template. I would like to treat the stacks as if they were nodes in an inventory, is this possible?

For example, I have one CloudFormation template and one Ansible playbook configured as follows:

- name: CloudFormation
  hosts: localhost
  connection: local
  gather_facts: false
  vars_files:
    - vars/global.yml
  tasks:
    - name: Network Stack
      cloudformation:
        stack_name: "{{ name }}-{{ env }}-network"

I then have a stack specific var file that I pass in at runtime ansible-playbook -e @one-prod-network.yml play.yml.

I need a way to run the playbook against all stacks in a group as if they were inventory items, for example:

[test]
one-test-network
two-test-network

[prod]
three-prod-network
four-prod-network

I thought roles might be the answer, but after investigating that I'm not so sure - obviously I don't want to duplicate the templates for each role. At present I am using a Makefile to run the command for each stack, but would prefer to do it in Ansible.

Answer 1

I would like to treat the stacks as if they were nodes in an inventory, is this possible?

From what I understand, yes you could do it by specifying that the ansible_connection is local on all hosts of a group cloud_formation then nest all your hosts (or hosts groups) inside it.

Here would be an example inventory:

[cloud_formation:children]
test
prod

[cloud_formation:vars]
ansible_connection=local

[test]
one-test-network name=one
two-test-network name=two

[test:vars]
env=test

[prod]
three-prod-network name=three
four-prod-network name=four

[prod:vars]
env=prod

Running this playbook against it:

- hosts: cloud_formation
  gather_facts: false

  tasks:
    - debug:
        msg:
          cloudformation:
            stack_name: "{{ name }}-{{ env }}-network"

Would yield:

ok: [one-test-network] => 
  msg:
    cloudformation:
      stack_name: one-test-network
ok: [two-test-network] => 
  msg:
    cloudformation:
      stack_name: two-test-network
ok: [three-prod-network] => 
  msg:
    cloudformation:
      stack_name: three-prod-network
ok: [four-prod-network] => 
  msg:
    cloudformation:
      stack_name: four-prod-network

---

Then, if my guess of what you are trying to achieve is correct, you could even simplify further, with the inventory:

[cloud_formation:children]
test
prod

[cloud_formation:vars]
ansible_connection=local

[test]
one-test-network
two-test-network

[prod]
three-prod-network
four-prod-network

Running against the playbook:

- hosts: cloud_formation
  gather_facts: false

  tasks:
    - debug:
        msg:
          cloudformation:
            stack_name: "{{ inventory_hostname }}"

Would yield:

ok: [one-test-network] => 
  msg:
    cloudformation:
      stack_name: one-test-network
ok: [two-test-network] => 
  msg:
    cloudformation:
      stack_name: two-test-network
ok: [three-prod-network] => 
  msg:
    cloudformation:
      stack_name: three-prod-network
ok: [four-prod-network] => 
  msg:
    cloudformation:
      stack_name: four-prod-network

---

Or, without a parent group, the inventory:

[test]
one
two

[test:vars]
ansible_connection=local

[prod]
three
four

[prod:vars]
ansible_connection=local

Run against the playbook:

- hosts: test, prod
  gather_facts: false

  tasks:
    - debug:
        msg:
          cloudformation:
            stack_name: >-
              {{ inventory_hostname -}}
              -{{ group_names[0] -}}
              -network
            ## /!\ Mind that this only works accuratly
            ## if the hosts are present in a single group

Would yield:

ok: [one] => 
  msg:
    cloudformation:
      stack_name: one-test-network
ok: [two] => 
  msg:
    cloudformation:
      stack_name: two-test-network
ok: [three] => 
  msg:
    cloudformation:
      stack_name: three-prod-network
ok: [four] => 
  msg:
    cloudformation:
      stack_name: four-prod-network