Provision a JSON file with Ansible while keeping indentation - json

Question

I want to provision a JSON file with Ansible. The content of this file is a variable in my Ansible's playbook.
And very important for my usecase: I need the indentation & line breaks to be exactly the same as in my variable.
The variable looks like this :
my_ansible_var:
{
"foobar": {
"foo": "bar"
},
"barfoo": {
"bar": "foo"
}
}
And it's use like this in my playbook :
- name: drop the gitlab-secrets.json file
copy:
content: "{{ my_ansible_var }}"
dest: "/some/where/file.json"
Problem: when this tasks is played, my file is provisionned but as a "one-line" file:
{ "foobar": { "foo": "bar" }, "barfoo": { "bar": "foo" } }
I tried several other ways:
Retrieve the base64 value of my JSON content, and use content: "{{ my_ansible_var | b64decode }}" : same problem at the end
I tried playing with YAML block indicator : none of the block indicators helped me with that problem
I tried adding some filters like to_json, to_nice_json(indent=2) : no more luck here
Question:
How in Ansible can I provison a JSON file while keeping the exact indentation I want ?

Answer 1

In your example my_ansible_var is a dict. If you don't need to access its keys in your playbook (e.g. my_ansible_var.foobar.foo) and just want it as JSON string for your copy task, force it to be a string.
There is type-detection feature in Ansible template engine, so if you feed it with dict-like or list-like string, it will be evaluated into object. See some details here.
This construction will work ok for your case:
---
- hosts: localhost
gather_facts: no
vars:
my_ansible_var: |
{
"foobar": {
"foo": "bar"
},
"barfoo": {
"bar": "foo"
}
}
tasks:
- copy:
content: "{{ my_ansible_var | string }}"
dest: /tmp/out.json
Note vertical bar in my_ansible_var definition and | string filter in content expression.