Append a list with loop in Ansible

Question

I'm trying to append new tunnel interface to empty list, but I'm getting the below error.

- name: empty list
  set_fact:
          list_tunnel: []

- name: create new list for tunnel
  set_fact:
        list_tunnel_new: "{{ list_tunnel + ['tunnel.{{item}}'] }}"
  loop: "{{ range(1,10)|list}}"

Error:

fatal: [SJL]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: 'item' is undefined\n\nThe error appears to be in '/etc/ansible/aws/interface_palo_facts.yaml': line 34, column 12, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n - name: print facts\n ^ here\n"}

Does this answer your question? [How can I make Ansible interpret a variable inside a variable?](https://stackoverflow.com/questions/67408680/how-can-i-make-ansible-interpret-a-variable-inside-a-variable) — β.εηοιτ.βε, Jul 19 '22 at 08:45
Also mind that you are getting this error in a task that you are not showing here `- name: print facts` — β.εηοιτ.βε, Jul 19 '22 at 08:47
And so, your `set_fact` should read `list_tunnel_new: "{{ list_tunnel + ['tunnel.' ~ item] }}"` — β.εηοιτ.βε, Jul 19 '22 at 08:47
here is the print_facts: - name: print facts debug: msg: "{{ list_tunnel_new }}" — Mike, Jul 19 '22 at 08:56
also , i tried to use your direction but getting below o/p , looks like it is not appending: ok: [SJL] => { "msg": [ "tunnel.9" ] } what i need is : [tunnel.1, tunnel.2, tunnel.3.......,tunnel.9 ] — Mike, Jul 19 '22 at 09:00
Because you made a mess in your variables names: `list_tunnel: "{{ list_tunnel + ['tunnel.' ~ item] }}"` — β.εηοιτ.βε, Jul 19 '22 at 09:24

score 3 · Answer 1 · edited Jul 19 '22 at 09:37

3

You can do it like this:

- name: create new list for tunnel
  set_fact:
    list_tunnel: "{{ list_tunnel | default([]) + ['tunnel.' + item | string] }}"
  loop: "{{ range(1,10) | list}}"

- debug:
    msg: "{{ list_tunnel }}"

or

- set_fact:
    list_tunnel: "{{ result }}"
  vars:
    prefix: tunnel
    a_list: "{{ range(1, 10) | list }}"
    result: "{{ [prefix] | product(a_list) | map('join', '.') | list }}"

edited Jul 19 '22 at 09:37

β.εηοιτ.βε

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answered Jul 19 '22 at 09:27

Abhijeet Kasurde

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How does Ansible works w that 'map(join, .) part? It's so weird to see that. And why is prefix required, why can't we simply put the string 'tunnel' as a string in the result variable. – Kevin C Aug 23 '23 at 14:18

score 1 · Answer 2 · answered Jul 19 '22 at 12:07

Create the list you want to add

  list_tunnel_add: "{{ ['tunnel']|product(range(1,10))|
                                  map('join','.')|
                                  list }}"

gives

  list_tunnel_add:
  - tunnel.1
  - tunnel.2
  - tunnel.3
  - tunnel.4
  - tunnel.5
  - tunnel.6
  - tunnel.7
  - tunnel.8
  - tunnel.9

Then concatenate the lists

  list_tunnel_new: "{{ list_tunel + list_tunnel_add }}"

^{Example of a complete playbook
- hosts: localhost
vars:
list_tunel: []
list_tunnel_add: "{{ ['tunnel']|product(range(1,10))|
map('join','.')|
list }}"
list_tunnel_new: "{{ list_tunel + list_tunnel_add }}"
tasks:
- debug:
var: list_tunnel_new

gives
list_tunnel_new:
- tunnel.1
- tunnel.2
- tunnel.3
- tunnel.4
- tunnel.5
- tunnel.6
- tunnel.7
- tunnel.8
- tunnel.9}

Append a list with loop in Ansible

2 Answers2

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