Ansible, iterate over multiple registers and make extended use of build in methods - ansible

Question

To start off I have all my variables defined in YAML
app_dir: "/mnt/{{ item.name }}"
app_dir_ext: "/mnt/{{ item.0.name }}"
workstreams:
- name: tigers
service_workstream: tigers-svc
app_sub_dir:
- inbound
- inbound/incoming
- inbound/error
- inbound/error/processed
- name: lions
service_workstream: lions-svc
app_sub_dir:
- inbound
- inbound/incoming
- inbound/error
- inbound/error/processed
You may note app_dir: "/mnt/{{ item.name }}" and app_dir_ext: "/mnt/{{ item.0.name }}" looking odd, so I originally had my variables set as below in YAML but decided to use the above mainly due to less lines in YAML when I have a large amount of workstreams.
workstreams:
- name: tigers
service_workstream: tigers-svc
app_dir: /mnt/tigers
...
I then have Ansible code to check if the directories exists, if not create them and apply permissions (!note, have taken this approach due to a ssh timeout on operation when using the file: module on a number of very big NFS mounted shares).
- name: Check workstreams app_dir
stat:
path: "{{ app_dir }}"
register: app_dir_status
with_items:
- "{{ workstreams }}"
- name: Check workstreams app_sub_dir
stat:
path: "{{ app_dir_ext }}/{{ item.1 }}/"
register: app_sub_dir_status
with_subelements:
- "{{ workstreams }}"
- app_sub_dir
- name: create workstreams app_dir
file:
path: "/mnt/{{ item.0.name }}"
state: directory
owner: "ftp"
group: "ftp"
mode: '0770'
recurse: yes
with_nested:
- '{{ workstreams }}'
- app_dir_status.results
when:
- '{{ item.1.stat.exists }} == false'
This is a little hacky but works, however I have a 2nd, 3rd, 4th path to check..etc
My question here is how to I update/refactor the above code to use <register_name>.stat.exists == false from both app_dir_status and app_sub_dir_status to control my task ?

Answer 1

You don't need to make nested loop! There's all required data inside app_sub_dir_status – just strip unnecessary items.
Here's simplified example:
---
- hosts: localhost
gather_facts: no
vars:
my_list:
- name: zzz1
sub:
- aaa
- ccc
- name: zzz2
sub:
- aaa
- bbb
tasks:
- stat:
path: /tmp/{{ item.0.name }}/{{ item.1 }}
register: stat_res
with_subelements:
- "{{ my_list }}"
- sub
- debug:
msg: "path to create '{{ item }}'"
with_items: "{{ stat_res.results | rejectattr('stat.exists') | map(attribute='invocation.module_args.path') | list }}"
You can iterate over stat_res.results | rejectattr('stat.exists') | list as well, but will have to construct path again as /tmp/{{ item.item.0.name }}/{{ item.item.1 }} – note double item, because first item is an element of stat_res.results which contain another item as element of your original loop for stat task.
P.S. Also I see no reason for your first task, as subdir task can detect all missing directories.