Ansible loop over a list to define a dynamic dictionary

Question

I am trying to define a dictionary FACTS_VAR in which the key must contain the word SUB. Argument_value and the value is true but when I loop over the variable Argument

hosts: all
gather_facts: true

vars:

  Argument:
    - value1
    - value2                      

tasks:

- name: DEFINING A variable
  set_fact:
    FACTS_VAR: {'SUB..item': true}
  loop: "{{Argument}}"

- debug:
    var: FACTS_VAR

I got this result so I don't know what is missing there. I am expecting to get a dictionary like this

FACTS_ENTRY:
   SUB.value1: true
   SUB.value2: true

TASK [debug] *****************************************************************************************************************
ok: [control] => {
    "FACTS_ENTRY": {
        "SUB..item": true
    }
}
ok: [ansible4] => {
    "FACTS_ENTRY": {
        "SUB..item": true
    }

score 2 · Accepted Answer · answered Jul 31 '22 at 20:14

Create the keys

facts_entry_keys: "{{ ['sub']|product(argument)|map('join','.')|list }}"

gives

facts_entry_keys:
  - sub.value1
  - sub.value2

Create the dictionary

facts_entry: "{{ dict(facts_entry_keys|product([true])) }}"

gives

facts_entry:
  sub.value1: true
  sub.value2: true

^{Example of a complete playbook
- hosts: localhost
vars:
argument:
- value1
- value2
facts_entry_keys: "{{ ['sub']|product(argument)|map('join','.')|list }}"
facts_entry: "{{ dict(facts_entry_keys|product([true])) }}"
tasks:
- debug:
var: facts_entry}

this is what i am looking for. It works like a magic, thank you so much for your efficient solution — medisamm, Aug 01 '22 at 20:16

score 1 · Answer 2 · answered Jul 31 '22 at 15:11

From your current description I understand only that you probably like to define variables somehow dynamically.

The following example could give some guidance.

---
- hosts: test
  become: false
  gather_facts: false

  vars:

    ARG:
      - val1
      - val2

  tasks:

  - name: Dynamically define variable
    set_fact:
      FACTS_VAR: "{ 'SUB_{{ item }}': true }"
    loop: "{{ ARG }}"

  - debug:
      var: FACTS_VAR

resulting into an output of

TASK [Dynamically define variable] **
ok: [test.example.com] => (item=val1)
ok: [test.example.com] => (item=val2)

TASK [debug] ************************
ok: [test.example.com] =>
  FACTS_VAR:
    SUB_val2: true

Please take note that according your current description there can be only one value as result.

Further Q&A

Build variable name at play level

thank you so much for the reply, exactly this is my problem that the `var` `FACTS_VAR` must take all the values given in input because i need after that to transform that `dictionary` into `JSON format` in the next task like this one [create_jason_file](https://stackoverflow.com/questions/63416703/how-to-write-a-json-file-using-ansible) — medisamm, Jul 31 '22 at 15:34

Ansible loop over a list to define a dynamic dictionary

2 Answers2