How to parse text with ansible using a nested list/dict? - ansible

Question

I have a text file that needs to be parsed so i can use it via a REST API with ansible.
10.0.0.0/16 Building-A
10.1.0.0/16 Building-A
10.2.0.0/16 Building-B
10.3.0.0/16 Building-B
I need to convert this text to something like this:
{
"parsed":[
{
"Building-A":[
"10.0.0.0/16",
"10.1.0.0/16"
]
},
{
"Building-B":[
"10.2.0.0/16",
"10.3.0.0/16"
]
}
]
}
Currently i run the following playbook to test the textparsing, without success. The list created is not unique.
- name: Test
hosts: localhost
tasks:
- name: Combine
ansible.builtin.set_fact:
parsed: "{{ (parsed | default([])) | union( [{item.split()[1]: item.split()[0] }] ) }}"
loop: "{{ lookup('file','hostgroups.txt').strip().splitlines() }}"
- name: Debug
ansible.builtin.debug:
var: parsed
ok: [localhost] => {
"parsed": [
{
"Building-A": "10.0.0.0/16"
},
{
"Building-A": "10.1.0.0/16"
},
{
"Building-B": "10.2.0.0/16"
},
{
"Building-B": "10.3.0.0/16"
}
]
}
Thanks for the tip with the helper variables and the groupby filter. Here is the final playbook:
- name: Test
hosts: localhost
# strategy: free
tasks:
- name: Get List
ansible.builtin.set_fact:
parsed_list: "{{ parsed_list | default([]) + [_item] }}"
loop: "{{ lookup('file','hostgroups.txt').strip().splitlines() }}"
vars:
_list: "{{ item.split() }}"
_item: "{{ {'Name': _list[1], 'Subnet': _list[0] } }}"
- name: Debug parsed_list
ansible.builtin.debug:
var: parsed_list
- name: Group parsed_list
ansible.builtin.set_fact.set_fact:
parsed_group: "{{ parsed_group | default([]) + [{_key: _value}] }}"
loop: "{{ parsed_list | groupby('Name') }}"
vars:
_key: "{{ item.0 }}"
_value: "{{ item.1 | map(attribute='Subnet') | list }}"
- name: Debug parsed_group
ansible.builtin.debug:
var: parsed_group

Answer 1

Parse the content, e.g.
- set_fact:
parsed_list: "{{ parsed_list|d([]) + [_item] }}"
loop: "{{ lookup('file','hostgroups.txt').splitlines() }}"
vars:
_array: "{{ item.split() }}"
_item: "{{ {'building': _array.1, 'ip': _array.0} }}"
gives
parsed_list:
- building: Building-A
ip: 10.0.0.0/16
- building: Building-A
ip: 10.1.0.0/16
- building: Building-B
ip: 10.2.0.0/16
- building: Building-B
ip: 10.3.0.0/16
Then, use filter groupby and create the list
- set_fact:
parsed: "{{ parsed|d([]) + [{_key: _val}] }}"
loop: "{{ parsed_list|groupby('building') }}"
vars:
_key: "{{ item.0 }}"
_val: "{{ item.1|map(attribute='ip')|list }}"
gives
parsed:
- Building-A:
- 10.0.0.0/16
- 10.1.0.0/16
- Building-B:
- 10.2.0.0/16
- 10.3.0.0/16
In some cases, a dictionary might be a better structure, e.g.
- set_fact:
parsed_dict: "{{ parsed_dict|d({})|combine({_key: _val}) }}"
loop: "{{ parsed_list|groupby('building') }}"
vars:
_key: "{{ item.0 }}"
_val: "{{ item.1|map(attribute='ip')|list }}"
gives
parsed_dict:
Building-A:
- 10.0.0.0/16
- 10.1.0.0/16
Building-B:
- 10.2.0.0/16
- 10.3.0.0/16