EX294 Transform data with filters and plugins Practice Test 4 — 15 Questions

Question 1

A playbook needs to set a fact 'total_memory' by summing the 'memory_mb' values from a list of servers. Which filter should be used?

Accepted Answer

{{ servers | map(attribute='memory_mb') | sum }}. It uses the `map` filter with the `attribute` parameter to extract the `memory_mb` value from each dictionary in the list, then pipes the resulting list of integers into the `sum` filter to compute the total. This is the standard Ansible idiom for summing a specific attribute across a list of dictionaries.

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Question 2

The playbook uses the community.general.parse_csv filter. Assuming the collection is installed, what is the type and structure of the 'parsed' variable?

Accepted Answer

A list of dictionaries: [{'name': 'Alice', 'age': '30'}, {'name': 'Bob', 'age': '25'}]. The `community.general.parse_csv` filter in Ansible parses CSV content into a list of dictionaries, where the first row is treated as headers and subsequent rows become dictionaries with those headers as keys. Option A correctly describes this output: a list of dictionaries with keys 'name' and 'age' and corresponding string values.

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A single string: 'Alice,30
Bob,25'

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A list of strings: ['name,age', 'Alice,30', 'Bob,25']

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A dictionary: {'Alice': '30', 'Bob': '25'}

Question 3

A playbook uses the 'debug' module to print a variable 'my_var' but the output is 'VARIABLE IS UNDEFINED'. The variable is defined in group_vars/all.yml. Which filter could be used to provide a default value and avoid this error?

Accepted Answer

{{ my_var | default('fallback') }}. The `default` filter in Ansible provides a fallback value when a variable is undefined, preventing the 'VARIABLE IS UNDEFINED' error. Using `{{ my_var | default('fallback') }}` ensures that if `my_var` is not defined in group_vars/all.yml or any other precedence level, the string 'fallback' is used instead of causing a failure.

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Question 4

Drag and drop the steps to set up a cron job that runs a script every day at 2 AM in the correct order.

Accepted Answer

Prepare script, test script, edit crontab, add entry with correct syntax, verify. Cron setup: prepare script, test, edit crontab, add entry with correct syntax, verify.

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Edit crontab, add entry, prepare script, test, verify

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Prepare script, edit crontab, add entry, test, verify

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Test script, prepare script, edit crontab, add entry, verify

Question 5

A playbook uses `{{ my_var | default('fallback') }}`. What is the effect?

Accepted Answer

If `my_var` is undefined, the expression evaluates to 'fallback'.. The `default` filter in Ansible (also known as `d()`) returns the specified fallback value only when the variable is undefined. If `my_var` is defined but empty or None, the filter returns the variable's value (empty string or None), not the fallback. This behavior is specific to the `default` filter's default mode; to also catch empty or None values, you must use `default('fallback', true)`.

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If `my_var` is defined but empty, the expression evaluates to 'fallback'.

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If `my_var` is defined but equal to None, the expression evaluates to 'fallback'.

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The filter raises an error because 'default' is not a valid filter.

Question 6

You have a list `my_list` containing `[0, 1, 2, '', 'hello']`. You want to extract the first truthy element that exists. Which chain achieves this?

Accepted Answer

`my_list | select('truthy') | first | default('')`. `select('truthy')` filters the list to include only elements that evaluate to `true` in Ansible/Jinja2 (non-zero numbers, non-empty strings, etc.), and `first` returns the first such element. The `default('')` provides a fallback if no truthy element exists. This chain correctly extracts `1` from the list `[0, 1, 2, '', 'hello']`.

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`my_list | list | first | default('')`

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`my_list | select('string') | first | default('')`

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`my_list | first | default('')`

Question 7

Consider the task: `- debug: msg={{ item | upper }}` with `loop: "{{ ['a','b'] }}"`. What will be the output?

Accepted Answer

Two debug messages: 'A' and 'B'. The `upper` filter in Ansible converts each string item in the loop to uppercase. The `loop` directive iterates over the list `['a','b']`, and for each iteration, the `{{ item | upper }}` expression applies the `upper` filter to the current item, resulting in `'A'` and `'B'`. The `debug` module then prints each transformed value as a separate message.

Answer

An error because upper expects a string, not a loop variable.

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Two debug messages: 'a' and 'b'

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One debug message with the list ['A','B']

Question 8

Given `{{ ['1', '2', '3'] | map('int') | list }}`, what is the result?

Accepted Answer

`[1, 2, 3]`. The `map('int')` filter in Ansible/Jinja2 converts each string element in the list to an integer. The `list` filter then materializes the generator into a list, resulting in `[1, 2, 3]`. Option B is correct because this is the standard behavior of the `map` filter with the `int` function.

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An error because 'int' is not a valid filter name.

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`['1', '2', '3']` as integers, but stored as strings.

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`['1', '2', '3']`

Question 9

Which TWO filters are commonly used for list manipulation in Ansible? (Select exactly two.)

Accepted Answer

`map`. The `map` filter is specifically designed for list manipulation in Ansible, allowing you to apply a transformation (such as extracting a specific attribute) to every element in a list. Option D is correct because the `select` filter is used to filter list items based on a condition, returning only those elements that match. Both are core Jinja2 filters commonly used in Ansible playbooks for processing lists.

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`default`

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`ternary`

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`regex_replace`

Question 10

Which THREE of the following are valid Ansible lookup plugins? (Select exactly three.)

Accepted Answer

`csvfile`. `csvfile` is a built-in Ansible lookup plugin that reads data from CSV files, allowing playbooks to parse structured tabular data. It is documented in the official Ansible lookup plugin list and is commonly used for dynamic inventory or configuration values.

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`map`

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`select`

Question 11

What is the effect of the `filter_plugins` setting in `ansible.cfg`?

Accepted Answer

It adds the directory to the default search path for filter plugins.. The `filter_plugins` setting in `ansible.cfg` adds the specified directory to the default search path for filter plugins, not replacing it. Ansible searches default locations like `~/.ansible/plugins/filter` and the `filter_plugins` directory relative to the playbook, in addition to any directories specified by this setting. Therefore, option D is correct.

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It sets the directory for filter plugins but only for the current playbook.

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It configures the path for lookup plugins, not filter plugins.

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It replaces the default search path for filter plugins with the specified directory.

Question 12

What is the output of the following playbook task?
```yaml
- name: Example task
  debug:
    msg: "{{ ['apple', 'banana'] | map('upper') | first }}"
```

Accepted Answer

'APPLE'. The playbook task likely uses a filter that extracts only the first element after applying `map('upper')`. For example, `{{ ['apple', 'banana'] | map('upper') | first }}` would output 'APPLE'. The `map` filter applies the `upper` filter to each element, but the `first` filter selects only the first item, resulting in the string 'APPLE'. Candidates may mistakenly think the entire list is returned, but this task explicitly retrieves a single element.

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An error because map expects a list of strings.

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['APPLE', 'BANANA']

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'apple'

Question 13

An Ansible playbook needs to convert a list of server names into a comma-separated string for an API call. Which filter should be applied to the list variable 'server_list'?

Accepted Answer

join(','). The `join` filter in Ansible is designed to concatenate list elements into a single string using a specified delimiter. Applying `join(',')` to `server_list` will produce a comma-separated string, exactly as required for the API call.

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map('regex_replace', '^', '')

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combine(',')

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regex_replace('
', ',')

Question 14

An administrator must parse an inventory file where hostnames are stored in YAML format under a list 'nodes'. The task needs to extract only hostnames that contain 'prod' in the name, then sort them in reverse order. Which combination of filters in a single Ansible expression achieves this?

Accepted Answer

nodes | select('match', '.*prod.*') | sort(reverse=True). The `select` filter with the `match` test returns only list items that match the regex `'.*prod.*'`, i.e., hostnames containing 'prod'. The `sort(reverse=True)` then sorts the resulting list in descending alphabetical order, fulfilling both requirements in a single Ansible expression.

Answer

nodes | regex_search('prod') | sort(True)

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nodes | map('regex_search', 'prod') | sort(reverse=True)

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nodes | reject('match', '.*prod.*') | sort(reverse=True)

Question 15

A playbook needs to generate a default value for a variable if it is undefined or empty. Which filter with a default value should be used?

Accepted Answer

my_var | default('fallback'). The `default` filter in Ansible is specifically designed to provide a fallback value when a variable is undefined or evaluates to an empty string (with the `omit` parameter). It is the idiomatic way to handle missing or empty variables in Jinja2 templates within Ansible playbooks, ensuring idempotency and avoiding undefined variable errors.

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my_var | fail('fallback')

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my_var | ternary('fallback', my_var)

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my_var | coalesce('fallback')