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)
``yaml
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)
`yaml
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:
`yaml
variable1: |
exactly as you see
will appear these three
lines of poetry
`
#### Output:
`yaml
variable1: |
exactly as you see
will appear these three
lines of poetry\n
`
Example 2: Using > Operator
#### Code:
`yaml
variable2: >
this is really a
single line of text
despite appearances
`
#### Output:
`yaml
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:
`yaml
---
- name: debug module Playbook
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
`
#### Playbook Execution:
`bash
$ 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