EX294 Transform data with filters and plugins Practice Question
An Ansible task uses the variable `{{ my_var | default(required=true) }}`. What happens if `my_var` is undefined?
⚠ Common exam trap
Many candidates confuse `default(required=true)` with setting a default value, thinking it will use the string 'required' or an empty string, when in fact it enforces mandatory variable definition and causes a failure.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The task fails with an error message
The `default(required=true)` filter in Ansible explicitly marks the variable as required. If `my_var` is undefined, the filter raises an error because it enforces that the variable must be provided, causing the task to fail with an error message. This is a deliberate mechanism to catch missing mandatory variables early in playbook execution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The task fails with an error message
Why this is correct
The `default` filter with `required=true` raises an undefined-variable error when `my_var` is absent, halting the task immediately. This satisfies the stem's constraint that an undefined variable must not silently fall back to a substitute value, unlike a plain `default('x')` which would return the fallback instead.
- ✗
The task skips the host
Why it's wrong here
The default filter with required=true raises an undefined-variable error, failing the task on that host rather than skipping it. Skipping is tempting because Ansible does skip hosts on unreachable or failed conditions, but an undefined mandatory variable aborts the play for that host instead.
- ✗
The task uses an empty string
Why it's wrong here
Supplying an empty string is what default() does without required=true, but required=true forces an error when the variable is undefined. The empty-string behaviour is tempting because it is the filter's normal fallback, yet the mandatory flag changes the outcome to a fatal undefined-variable failure.
- ✗
The task uses the string 'required'
Why it's wrong here
The string 'required' is never substituted; required=true is a keyword argument that makes the filter raise an error on an undefined variable. Treating it as a literal value is tempting because default() normally returns its argument, but here the argument configures error behaviour instead.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This EX294 practice question is part of Courseiva's free Red Hat certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the EX294 exam.