set_fact in dictionary with dynamic variable name - ansible-2.x

Question

I have an ansible inventory list like this:
domaenenliste:
"01":
dhcp_start: 10.43.12.0
dhcp_ende: 10.43.15.254
server_id: 3
"15":
"16":
dhcp_start: 10.43.128.26
dhcp_ende: 10.43.131.255
server_id: 2
And I want to set facts within this structure, expected output:
domaenenliste:
"01":
dhcp_start: 10.43.12.0
dhcp_ende: 10.43.15.254
server_id: 3
"15":
partner: foobar
"16":
dhcp_start: 10.43.128.26
dhcp_ende: 10.43.131.255
server_id: 2
I tried to assign it like this:
- debug:
var: dom
- name: Test set
set_fact:
"{'{{domaenenliste[dom]}}':{'partner':'foobar'}}"
- debug:
var: domaenenliste[dom].partner
- debug:
var: domaenenliste['16']
Which creates the following output:
TASK [calculate_missing_inventory_variables : debug] ****************************************************************************
task path: /home/mpw/gits/ansible-ffms/roles/calculate_missing_inventory_variables/tasks/main.yml:5
ok: [des1] => {
"dom": "15"
}
TASK [calculate_missing_inventory_variables : Test set] *************************************************************************
task path: /home/mpw/gits/ansible-ffms/roles/calculate_missing_inventory_variables/tasks/main.yml:8
ok: [des1] => {
"ansible_facts": {
"_raw_params": {
"": {
"partner": "foobar"
}
}
},
"changed": false
}
TASK [calculate_missing_inventory_variables : debug] ****************************************************************************
task path: /home/mpw/gits/ansible-ffms/roles/calculate_missing_inventory_variables/tasks/main.yml:17
ok: [des1] => {
"domaenenliste[dom].partner": "VARIABLE IS NOT DEFINED!"
}
TASK [calculate_missing_inventory_variables : debug] ****************************************************************************
task path: /home/mpw/gits/ansible-ffms/roles/calculate_missing_inventory_variables/tasks/main.yml:20
ok: [des1] => {
"domaenenliste['16']": {
"dhcp_ende": "10.43.131.255",
"dhcp_start": "10.43.128.26",
"server_id": 2
}
}
As the debug output shows, the variable is still unassigned. Accessing this structure with this syntax works. But I can't make changes to it.
Does someone have an idea how to set this correctly?
Thanks for your help in advance!
Regards,
Matthias

Answer 1

You cannot assign subkey of a dictionary in Ansible, override whole variable with required modifications:
---
- hosts: localhost
gather_facts: no
vars:
domaenenliste:
"01":
dhcp_start: 10.43.12.0
dhcp_ende: 10.43.15.254
server_id: 3
"15":
"16":
dhcp_start: 10.43.128.26
dhcp_ende: 10.43.131.255
server_id: 2
tasks:
- set_fact:
domaenenliste: "{{ domaenenliste | combine(new_leaf) }}"
vars:
new_leaf:
"15":
partner: foobar
- debug:
msg: "{{ domaenenliste }}"