How to join a list of strings in 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') }}" 

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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.

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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"