Output hosts from ansible inventory group to a template [duplicate] - ansible

Question

In Ansible, I have a list of strings that I want to join with newline characters to create a string, that when written to a file, becomes a series of lines. However, when I use the join() filter, it works on the inner list, the characters in the strings, and not on the outer list, the strings themselves. Here's my sample code:
# Usage: ansible-playbook tst3.yaml --limit <GRP>
---
- hosts: all
remote_user: root
tasks:
- name: Create the list
set_fact:
my_item: "{{ item }}"
with_items:
- "One fish"
- "Two fish"
- "Red fish"
- "Blue fish"
register: my_item_result
- name: Extract items and turn into a list
set_fact:
my_list: "{{ my_item_result.results | map(attribute='ansible_facts.my_item') | list }}"
- name: Examine the list
debug:
msg: "{{ my_list }}"
- name: Concatenate the public keys
set_fact:
my_joined_list: "{{ item | join('\n') }}"
with_items:
- "{{ my_list }}"
- name: Examine the joined string
debug:
msg: "{{ my_joined_list }}"
I want to get output that looks like:
One fish
Two fish
Red fish
Blue Fish
What I get instead is:
TASK: [Examine the joined string] *********************************************
ok: [hana-np-11.cisco.com] => {
"msg": "B\nl\nu\ne\n \nf\ni\ns\nh"
}
ok: [hana-np-12.cisco.com] => {
"msg": "B\nl\nu\ne\n \nf\ni\ns\nh"
}
ok: [hana-np-13.cisco.com] => {
"msg": "B\nl\nu\ne\n \nf\ni\ns\nh"
}
ok: [hana-np-14.cisco.com] => {
"msg": "B\nl\nu\ne\n \nf\ni\ns\nh"
}
ok: [hana-np-15.cisco.com] => {
"msg": "B\nl\nu\ne\n \nf\ni\ns\nh"
}
How do I properly concatenate a list of strings with the newline character?

Answer 1

Solution
join filter works on lists, so apply it to your list:
- name: Concatenate the public keys
set_fact:
my_joined_list: "{{ my_list | join('\n') }}"
Explanation
While my_list in your example is a list, when you use with_items, in each iterationitem is a string. Strings are treated as lists of characters, thus join splits them.
It’s like in any language: when you have a loop for i in (one, two, three) and refer to i inside the loop, you get only one value for each iteration, not the whole set.
Remarks
Don’t use debug module, but copy with content to have\n rendered as newline.
The way you create a list is pretty cumbersome. All you need is (quotation marks are also not necessary):
- name: Create the list
set_fact:
my_list:
- "One fish"
- "Two fish"
- "Red fish"
- "Blue fish"