Combine nested dictionaries in ansible - dictionary

Question

I have 2 different dictionaries that contains application information I need to join together.
landscape_dictionary:
{
"app_1": {
"Category": "application",
"SolutionID": "194833",
"Availability": null,
"Environment": "stage",
"Vendor/Manufacturer": null
},
"app_2": false
}
app_info_dictionary:
{
"app_1": {
"app_id": "6886817",
"owner": "owner1#nomail.com",
"prod": [
"server1"
],
"stage": []
},
"app_2": {
"app_id": "3415012",
"owner": "owner2#nomail.com",
"prod": [
"server2"
],
"stage": [
"server3"
]
}
}
This is the code I'm using to join both dictionaries
- set_fact:
uber_dict: "{{app_info_dictionary}}"
- set_fact:
uber_dict: "{{ uber_dict | default ({}) | combine(new_item, recursive=true) }}"
vars:
new_item: "{ '{{item.key}}' : { 'landscape': '{{landscape_dictionary[item.key]|default(false)}}' } }"
with_dict: "{{ uber_dict }}"
- debug:
msg: "{{item.key}}: {{item.value}}"
with_dict: "{{uber_dict}}"
If the value in the landscape_dictionary is false it will add it to the uber_dict without problems. But if the value contains information, it fails.
This is the error:
fatal: [127.0.0.1]: FAILED! => {"msg": "|combine expects dictionaries, got u\"{ 'app_1' : { 'landscape': '{u'Category': u'application', u'SolutionID': u'194820', u'Availability': None, u'Environment': 'stage', u'Vendor/Manufacturer': None}' } }\""}
What could be the problem?
Do I need to do an extra combine when I set the var in the set_fact?
Thanks

Answer 1

As #DustWolf notes in the comments,
For anyone from the Internet looking for the answer to: "How tp combine nested dictionaries in ansible", the answer is | combine(new_item, recursive=true)
This solves a closely related issue that has baffled myself and my team for months.
I will demonstrate:
Code:
---
- hosts: localhost
gather_facts: false
vars:
my_default_values:
key1: value1
key2:
a: 10
b: 20
my_custom_values:
key3: value3
key2:
a: 30
my_values: "{{ my_default_values | combine(my_custom_values, recursive=true) }}"
tasks:
- debug: var=my_default_values
- debug: var=my_values
Output:
ok: [localhost] =>
my_values:
key1: value1
key2:
a: 30
key3: value3
Note how key2 was completely replaced, thus losing key2.b
We changed this to:
my_values: "{{ my_default_values | combine(my_custom_values, recursive=true) }}"
Output:
my_values:
key1: value1
key2:
a: 30
b: 20
key3: value3

Answer 2

This syntax is not legal, or at the very least doesn't do what you think:
new_item: "{ '{{item.key}}' : { 'landscape': '{{landscape_dictionary[item.key]|default(false)}}' } }"
Foremost, ansible will only auto-coerce JSON strings into a dict, but you have used python syntax.
Secondarily, the way to dynamically construct a dict is not to use jinja2 to build up text but rather use the fact that jinja2 is almost a programming language:
new_item: "{{
{
item.key: {
'landscape': landscape_dictionary[item.key]|default(false)
}
}
}}"
Any time you find yourself with nested jinja2 interpolation blocks, that is a code smell that you are thinking about the problem too much as text (by nested, I mean {{ something {{nested}} else }})