How to concatenate string in YAML? - yaml

Question

I am writing a playbook in which I need to execute mysql query and pass
output in json format. playbook code working fine just I want facing error in string concatenate part. If I am passing sample json string it is working fine.
- name: Execute php script with json parameter
command: php -f /path/to/php/test.php "{'colors':{'red','blue','yellow'}}"
register: php_output
output.stdout_lines is variable already set in my playbook which contains output in {'red','blue','yellow'} format.
- name: Execute php script with json parameter
command: php -f /path/to/php/test.php '{"stdout_lines": {{output.stdout_lines}} }'
register: php_output
So how can I concatenate output.stdout_lines variable in '{"stdout_lines": {{output.stdout_lines}} }' ? any suggestions

Answer 1

stdout_lines was created for convenience. Back in the day we only had stdout. Which is what you want, I think:
command: php -f /path/to/php/test.php '{"stdout_lines": {{output.stdout}} }'
and if you want to really concat yourself, say because you have your own list of strings then you can use the Jinja2 built-in filter join:
- hosts: localhost
gather_facts: False
tags: so9
vars:
- str_list: ['Hello', 'world', '!', ]
tasks:
- debug: msg="orig list={{ str_list }}"
- debug: msg="concated = {{ str_list | join(' ') }}"
- set_fact: concated_str="{{ str_list | join(' ') }}"
- debug: msg="assigned to a variable concated_str = {{ concated_str }}"

Answer 2

Try like this.
vars:
- img_path: "/var/lib/libvirt/images/{{ instance_name }}-disk2.img"
Where instance name is a another variable

Answer 3

This will do
- name: Generate JSON output based on template
template: src=colors.json.j2 dest=/tmp/colors.json
with_items: colors
It will generate a file like
{'colors':
{
'blue',
'red',
'green',
}
}

Answer 4

The to_json filter is what you want.
Ansible doesn't store variables as JSON strings, it stores them as Python objects. When you're debugging e.g. with -vvv, Ansible displays these Python objects as JSON strings, but that's for your convenience.
To produce the desired command:
- name: Execute php script with json parameter
vars:
# define my desired object
my_object:
colors: "{{ output.stdout_lines }}"
# my_object contains a dict with a single key
# "colors" who's value is the list contained
# in output.stdoutlines
command: "php -f /path/to/php/test.php {{ my_object | to_json | quote }}"
register: php_output
to_json takes the object stored in my_object and outputs a JSON string.
quote automatically handles any shell quoting that might be required for the JSON string. e.g. If my JSON string contains double-quotes, quote will wrap the whole JSON string in single-quotes.