EX294 Transform data with filters and plugins Practice Question
This EX294 practice question tests your understanding of transform data with filters and plugins. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Your organization manages a fleet of 500 web servers running RHEL 8. Each server has a custom fact file /etc/ansible/facts.d/web.fact containing:
You have a playbook that needs to configure the firewall to allow traffic on the port defined in the custom fact for each server. The playbook uses the 'ansible_local' variable to access these facts. However, some servers have the custom fact file missing or malformed. The task to open the firewall port fails on those servers with 'VARIABLE IS UNDEFINED'. You need to implement a solution that handles missing custom facts gracefully, setting a default port of 8080 if the fact is not defined, and still log a warning. Which approach should you take?
Use 'ignore_errors: yes' on the firewall task and then check the result with 'failed_when' to set a default.
Why wrong: Ignore_errors hides all failures, not just missing facts, and does not set a default port.
B
Use a 'set_fact' task with 'port: "{{ ansible_local.web.port | default(8080) }}"' and add a 'debug' task with 'when: ansible_local.web.port is undefined' to warn.
Correct: sets default and warns.
C
Use 'block' and 'rescue' to catch the error and then set the fact.
Why wrong: Block/rescue can work but is more verbose and less efficient than default filter.
D
Create a separate playbook for servers without the fact file, running a different role.
Why wrong: Too complex and not dynamic; does not handle individual server variations.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a 'set_fact' task with 'port: "{{ ansible_local.web.port | default(8080) }}"' and add a 'debug' task with 'when: ansible_local.web.port is undefined' to warn.
Option B is correct because it uses the `default` filter to gracefully handle undefined variables, setting a fallback port of 8080 when the custom fact is missing or malformed. The additional `debug` task with `when: ansible_local.web.port is undefined` provides a warning without causing the playbook to fail. This approach aligns with the EX294 objective of transforming data with filters and plugins, specifically using Jinja2 filters to manage missing data.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use 'ignore_errors: yes' on the firewall task and then check the result with 'failed_when' to set a default.
Why it's wrong here
Ignore_errors hides all failures, not just missing facts, and does not set a default port.
✓
Use a 'set_fact' task with 'port: "{{ ansible_local.web.port | default(8080) }}"' and add a 'debug' task with 'when: ansible_local.web.port is undefined' to warn.
Why this is correct
Correct: sets default and warns.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use 'block' and 'rescue' to catch the error and then set the fact.
Why it's wrong here
Block/rescue can work but is more verbose and less efficient than default filter.
✗
Create a separate playbook for servers without the fact file, running a different role.
Why it's wrong here
Too complex and not dynamic; does not handle individual server variations.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may overcomplicate the solution with error handling constructs like `ignore_errors` or `block/rescue`, instead of using the simple and idiomatic Jinja2 `default` filter, which is the most efficient and Ansible-native way to handle undefined variables.
Detailed technical explanation
How to think about this question
The `default` filter in Ansible is a Jinja2 filter that returns a specified default value if the variable is undefined, but it does not modify the underlying fact; it only provides a fallback at evaluation time. In this scenario, `ansible_local.web.port | default(8080)` ensures the task uses 8080 when the fact is missing, while the `debug` task with `when: ansible_local.web.port is undefined` checks the original variable state, not the filtered value, allowing a warning to be logged. Real-world usage often involves combining `default` with `mandatory` to enforce required facts while providing sensible defaults for optional ones.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the EX294 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Transform data with filters and plugins — This question tests Transform data with filters and plugins — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a 'set_fact' task with 'port: "{{ ansible_local.web.port | default(8080) }}"' and add a 'debug' task with 'when: ansible_local.web.port is undefined' to warn. — Option B is correct because it uses the `default` filter to gracefully handle undefined variables, setting a fallback port of 8080 when the custom fact is missing or malformed. The additional `debug` task with `when: ansible_local.web.port is undefined` provides a warning without causing the playbook to fail. This approach aligns with the EX294 objective of transforming data with filters and plugins, specifically using Jinja2 filters to manage missing data.
What should I do if I get this EX294 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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