How to Break a String Over Multiple Lines with Ansible and YAML

How to use multi-line YAML variables in Ansible using the "|", Literal Block Scalar, and the ">", Folded Block Scalar, operators. Plus how to elide the new line "\n" at the end of the line and print multi-line with debug module on a terminal.

November 22, 2023

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How to Break a String Over Multiple Lines with Ansible and YAML

Welcome to another episode of Ansible Pilot! I’m Luca Berton, and today we’ll explore a handy technique in Ansible – breaking strings over multiple lines using YAML. This can be especially useful when dealing with multiline text in your Ansible playbooks. Let’s dive in and explore the two operators that make this possible: the | (Literal Block Scalar) and the > (Folded Block Scalar).

The Basics: `|` and `>` Operators

In Ansible, breaking a string over multiple lines is accomplished using two main operators:

| (Literal Block Scalar): This operator instructs Ansible to treat the string as a literal block scalar, preserving the newlines within the string.
> (Folded Block Scalar): This operator tells Ansible to treat the string as a folded block scalar, collapsing all newlines into a single space.

Let’s illustrate these concepts with some examples.

Example 1: Using `|` (Literal Block Scalar)

my_variable: |
  This is a
  multiline string

In this example, my_variable will be a multiline string, preserving the newline characters.

Example 2: Using `>` (Folded Block Scalar)

my_variable: >
  This is a
  multiline string

In this case, my_variable will be a single-line string with spaces replacing the newlines.

The key difference is that | preserves newlines, while > collapses them.

Examples

Now, let’s look at some practical examples to solidify our understanding.

Example 1: Variable Definitions

Code:

variable1: |
  exactly as you see
  will appear these three
  lines of poetry

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Output:

variable1: |
  exactly as you see
  will appear these three
  lines of poetry\n

Example 2: Using `>` Operator

Code:

variable2: >
  this is really a
  single line of text
  despite appearances

Output:

variable2: this is really a single line of text despite appearances\n

In the second example, variable2 collapses into a single line.

Removing Newline at the End

To remove the newline at the end of strings, simply add a - after the | or > operator.

Running a Playbook

Let’s see these examples in action by running an Ansible playbook.

Playbook Code:

---
- name: debug module demo
  hosts: all
  vars:
    variable1: |-
      exactly as you see
      will appear these three
      lines of poetry      
    variable2: >-
      this is really a
      single line of text
      despite appearances      
  tasks:
    - name: print variable1
      ansible.builtin.debug:
        var: variable1
    - name: print variable2
      ansible.builtin.debug:
        var: variable2

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Playbook Execution:

$ ansible-playbook -i inventoryfile playbook.yml

This playbook will execute, and the debug module will print the values of variable1 and variable2.

Additional Tip: Splitting Multiline Strings

If you want to work with the multiline structure, you can split the string using the split('\n') method.

Code:

- name: debug module demo
  hosts: all
  vars:
    variable1: |-
      exactly as you see
      will appear these three
      lines of poetry      
    variable2: >-
      this is really a
      single line of text
      despite appearances      
  tasks:
    - name: print variable1
      ansible.builtin.debug:
        msg: "{{ variable1.split('\n') }}"
    - name: print variable2
      ansible.builtin.debug:
        var: variable2

Execution:

$ ansible-playbook -i inventoryfile playbook.yml

This will output an array for variable1 with each line as a separate element.

Recap

Congratulations! You’ve now mastered the art of breaking strings over multiple lines in Ansible using the | and > operators. These techniques are invaluable when dealing with multiline text in your playbooks. Feel free to explore and integrate these methods into your Ansible workflows. Happy automating! Subscribe to the YouTube channel, Medium, and Website, X (formerly Twitter) to not miss the next episode of the Ansible Pilot.