Quoting

Quoting in Ansible can be a bit tricky. This page will give you a quick overview of the different types of quoting and how to use them.

Referencing variables in a playbook

In playbooks you can use Jinja2 templating language to reference variables. Playbooks need to be valid YAML, so you need to quote the variables in a way that YAML understands. Most of the time you can use double quotes " and single quotes ' on playbooks interchangeably.

Some keywords like when and register expect variables and therefore you don't need to quote there.

Correct exampleIncorrect example

debug:
  msg: '{{ mymessage }}/foo.cfg'

debug:
  msg: "{{ mymessage }}/foo.cfg"

# Here we don't need to quote the variable
when: inventory_hostname in groups['webserver']
register: myvar

debug:
  msg: {{ mymessage }}/foo.cfg # (1)!

1. This playbook will fail with an error like

    The offending line appears to be:
    debug:
        msg: {{ mymessage }}
            ^ here
   
        We could be wrong, but this one looks like it might be an issue with
        missing quotes. Always quote template expression brackets when they
        start a value. For instance:
   
            with_items:
            - {{ foo }}
   
        Should be written as:
   
            with_items:
            - "{{ foo }}"
   

Multiple types of quotes

If you need to to define quotes itself in a line, you need to use differents quotes arround the string.

The desired command to be run is:

echo 'Hello <name>'
              ^ Variable in ansible

Here we need to add multiple quotes so that ansible knows how to formulate the command.

shell:
    cmd: "echo 'Hello {{ name }}'"

Referencing variables in a Jinja2 template

Jinja templates(.j2) are are not parsed as YAML and therefore don't require quoting like ansible playbooks.

template.j2

Hello {{ mymessage }}

When to quote

Sometimes you don't need to quote variables.

Here is an example using the when keyword in YAML:

playbook.yml

# Only run when the current host is the same as the host in the loop
when: inventory_hostname == hostvars[item]['inventory_hostname']

This can be confusing, so let's break it down:

Name	Description
inventory_hostname	A variable referencing the current host
==	Equal operation
hostvars[]	A function calling hostvariables of a certain host
item	A variable referencing the current item in the loop
'inventory_hostname'	Is a sting referencing the variable name that we want to access from the hostvars[] funtion

This is similar in Jinja2 templates. Here is an example that is even more tricky:

template.j2

# Set the last host in the dns group as the master
{% if inventory_hostname in hostvars[groups['dns']|last]['inventory_hostname'] %}
  master = true
{% endif %}

Again let's break it down:

Name	Description
inventory_hostname	A variable referencing the current host
in	In operation (is this string in the compare value?)
hostvars[]	A function calling hostvariables of a certain host
groups[]	A function calling groupmembers of a certain group
'dns'	A string referencing the name of the group we want to get
|last	A Jinja2 filter extracting the last item in a list
'inventory_hostname'	Is a sting referencing the variable name that we want to access from the hostvars[] funtion

Reference

Ansble docs - quoting