CODEWITHSUNDEEP
syntaxansibleyaml
Julien
Julien

Reputation: 3085

YAML syntax for set_fact and vars in ansible

I have difficulties to get the differences between the following syntaxes when I set vars or facts in a YAML role:

vars:
  app_path1: "{{ (ansible_facts.env.ProgramFiles + '\\\\' + item.installation_directory) if item.executable else root_dir }}"
  app_path2: >
      {{ (ansible_facts.env.ProgramFiles + '\\' + item.installation_directory) if item.executable else root_dir }}   
  app_path3: |
      {{ (ansible_facts.env.ProgramFiles + '\\' + item.installation_directory) if item.executable else root_dir }}

Here is the result:

{        
  "app_path1": "C:\\Program Files\\\\MyCompany\\TheAppName",
  "app_path2": "C:\\Program Files\\\\MyCompany\\TheAppName\n",
  "app_path3": "C:\\Program Files\\\\MyCompany\\TheAppName\n"
}

Why app_path2 and app_path3 added a mysterious \n at the end? And why must I escape twice the backslashes in app_path1? It's a kind of black magic for me.

Upvotes: 2

Views: 387

Answers (1)

β.εηοιτ.βε
β.εηοιτ.βε

Reputation: 39264

For the new line, this is the behaviour of those two YAML style indicator.
There is "strip chomping indicator" to get rid of them though:

So, app_path2 and app_path3 should be

app_path2: >-
  {{ 
    (ansible_facts.env.ProgramFiles + '\\' + item.installation_directory) 
    if item.executable else root_dir 
  }}
app_path3: |-
  {{ 
    (ansible_facts.env.ProgramFiles + '\\' + item.installation_directory) 
    if item.executable else root_dir 
  }}

As for the double escaping, this is quite simple, since you are in a double quoted string, this remark applies:

The double-quoted style is specified by surrounding “"” indicators. This is the only style capable of expressing arbitrary strings, by using “\” escape sequences. This comes at the cost of having to escape the “\” and “"” characters.

Source: https://yaml.org/spec/1.2.2/#73-flow-scalar-styles

Since you want to display two backslashes and that you have to escape them both, you end up with four of them.

Note: a pretty good tool for the explanation of all this is https://yaml-multiline.info

Upvotes: 2

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