EX294 Transform data with filters and plugins Practice Test 5 — 15 Questions

Question 1

A security team requires that all passwords in an Ansible vault be encrypted with a different key from the host variables. They want to use a custom lookup plugin that fetches secrets from an external API. Which plugin type should be developed?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Lookup plugin. A lookup plugin is the correct choice because it is designed to retrieve data from external sources (like an API) and return it as a string or list for use in Ansible playbooks. This aligns with the requirement to fetch secrets from an external API, and lookup plugins can be used directly in variables or templates without modifying the host state.

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Module

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Action plugin

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Filter plugin

Question 2

An Ansible playbook needs to dynamically include a set of variables based on the environment (dev/staging/prod). The developer wants to use a variable from a lookup plugin that returns a YAML file path. Which lookup plugin is most appropriate for fetching a file’s contents?

Accepted Answer

file. The `file` lookup plugin is the most appropriate for fetching the contents of a file from the control node, as it reads the entire file and returns its content as a string. This is ideal for dynamically including variable files based on environment (e.g., `{{ lookup('file', 'vars/{{ env }}.yml') }}`), allowing the playbook to load environment-specific YAML data.

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env

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pipe

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template

Question 3

A company uses Ansible Tower and has defined a custom inventory script. The inventory returns JSON with nested groups. The playbook needs to list all hosts from a specific group 'webservers' that are not in the 'drain' subgroup. Which combination of filters correctly extracts these hosts?

Accepted Answer

{{ groups['webservers'] | difference(groups['drain']) }}. The `difference` filter in Ansible returns the elements of the first list that are not present in the second list. This directly matches the requirement: all hosts in the 'webservers' group that are not in the 'drain' subgroup.

Answer

{{ groups['webservers'] | symmetric_difference(groups['drain']) }}

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Answer

Question 4

Which TWO filters are commonly used to transform strings in Ansible? (Select exactly two.)

Accepted Answer

regex_replace. `regex_replace` is a built-in Jinja2 filter in Ansible that allows you to transform strings by replacing substrings that match a regular expression pattern. This is commonly used for string manipulation tasks such as sanitizing user input or formatting output.

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items2dict

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flatten

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dict2items

Question 5

Which THREE features are provided by Ansible's filter plugins? (Select exactly three.)

Accepted Answer

Data transformation (e.g., format dates, modify strings). Filter plugins in Ansible are used to transform data within Jinja2 templates. Option B is correct because filters like `| date`, `| regex_replace`, and `| upper` directly perform data transformation tasks such as formatting dates and modifying strings, which is a core purpose of filter plugins.

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Defining new Ansible modules

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Fetching data from external APIs

Question 6

Refer to the exhibit. What is the output of the debug task?

Accepted Answer

192.168.1.10. The `debug` task in Ansible uses the `msg` parameter to display the value of a variable. In the exhibit, the variable `ansible_default_ipv4.address` is referenced, which returns the IPv4 address of the default network interface. Since the host's default interface is eth0 with IP 192.168.1.10, the debug output is that IP address. Option D correctly shows the output as '192.168.1.10'.

Answer

10.0.0.5

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[ '192.168.1.10' ]

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eth0

Question 7

An Ansible playbook retrieves a JSON response from an API and stores it in the variable `api_response`. The JSON structure is a list of objects, each with keys `name`, `status`, and `id`. The team needs to create a list of names for objects where status is 'active'. Which filter should be used?

Accepted Answer

{{ api_response | selectattr('status', 'equalto', 'active') | map(attribute='name') | list }}. It uses `selectattr` to filter the list of objects to only those where `status` equals 'active', then `map` to extract the `name` attribute from each filtered object, and finally `list` to convert the result into a list. This is the standard Ansible approach for filtering a list of dictionaries and extracting specific keys.

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Answer

Answer

Question 8

An administrator needs to combine two dictionaries, `base_config` and `user_config`, where keys in `user_config` should override keys in `base_config`, and nested dictionaries should be merged recursively. Which filter syntax achieves this?

Accepted Answer

{{ base_config | combine(user_config, recursive=True) }}. The `combine` filter in Ansible with `recursive=True` merges two dictionaries, with `user_config` overriding `base_config`, and recursively merges nested dictionaries. This matches the requirement exactly, as `recursive=True` ensures that nested structures are combined rather than replaced outright.

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Answer

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Question 9

A developer wrote a custom filter plugin in a Python file `my_filters.py` and placed it in the directory `./filter_plugins/`. The playbook fails with 'ERROR! no filter named 'my_custom_filter''. The playbook is located in `/home/user/project/playbook.yml`. The `ansible.cfg` file in the same directory does not set `filter_plugins`. Which is the most likely cause?

Accepted Answer

The plugin file must be a Python module with a class named `FilterModule` and the filter function must be listed in the `filters` method. Ansible requires custom filter plugins to be Python modules that define a class named `FilterModule` with a `filters()` method returning a dictionary mapping filter names to their implementing functions. Without this structure, Ansible cannot discover or register the filter, causing the 'no filter named' error.

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The filter file must be named `__init__.py`

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The filter function must be imported in the playbook via `filter_plugins: my_filters`

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The filter function name does not match the class name in the plugin

Question 10

An Ansible task uses the variable `{{ my_var | default(required=true) }}`. What happens if `my_var` is undefined?

Accepted Answer

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.

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The task skips the host

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The task uses an empty string

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The task uses the string 'required'

Question 11

Given a list of dictionaries `users` with keys `name` and `role`, a playbook needs to create a list of names where role is 'admin'. Which expression achieves this?

Accepted Answer

{{ users | selectattr('role', 'equalto', 'admin') | map(attribute='name') | list }}. It first uses `selectattr` to filter the list of dictionaries, keeping only those where `role` equals `'admin'`, then applies `map(attribute='name')` to extract the `name` values from the filtered dictionaries, and finally converts the result to a list with the `list` filter. This produces a list of names for admin users.

Answer

{{ users | map(attribute='name') | selectattr('role', 'equalto', 'admin') | list }}

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{{ users | json_query("[?role=='admin'].{name: name}") }}

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Question 12

A playbook has a dictionary `config` that maps service names to ports. The team wants to iterate over both keys and values in a task. Which filter should be used to convert the dictionary into a list of key-value pairs?

Accepted Answer

dict2items. The `dict2items` filter is the correct choice because it converts a dictionary into a list of key-value pairs, each represented as a dictionary with `key` and `value` keys. This is the standard Ansible filter for iterating over both keys and values in a `loop` within a task, enabling access to `item.key` and `item.value`.

Answer

items2dict

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flatten

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json_query

Question 13

Which TWO filters are commonly used to manipulate JSON data in Ansible? (Select exactly two.)

Accepted Answer

from_json. (from_json) is correct because it converts a JSON string into an Ansible data structure (dict or list), enabling further manipulation with filters like json_query. This is essential when parsing API responses or configuration files that return JSON-formatted strings.

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flatten

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regex_replace

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to_json

Question 14

Which TWO filters can be used to conditionally select elements from a list based on a test? (Select exactly two.)

Accepted Answer

reject. In Ansible, the `reject` filter removes elements from a list that match a given condition, effectively selecting only those that do not match. The `select` filter does the opposite: it keeps elements that match the condition. Both are used for conditional selection from a list based on a test, making C and D correct.

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map

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combine

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flatten

Question 15

An Ansible role uses a variable "server_list" which is a list of dictionaries. Each dictionary has a key "ports" which should be a list of integers. However, due to inconsistent input, "ports" could be a comma-separated string (e.g., "80,443") or already a list of integers (e.g., [80,443]). The engineer wants to normalize "ports" to always be a list of integers for further processing. Which of the following tasks correctly normalizes the "ports" field?

Accepted Answer

- set_fact:
    server_list: "{{ server_list | map('combine', {'ports': (item.ports is string) | ternary(item.ports | split(','), item.ports)}) }}"
  loop: "{{ server_list }}". It uses the `ternary` filter to check if `item.ports` is a string; if true, it splits the string by commas into a list, otherwise it keeps the existing list. This ensures the `ports` field is always normalized to a list of integers, handling both inconsistent input formats.

Answer

- set_fact:
    server_list: "{{ server_list | map('combine', {'ports': item.ports | split(',')}) }}"
  loop: "{{ server_list }}"

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- set_fact:
    server_list: "{{ server_list | map('combine', {'ports': [item.ports] | flatten}) }}"
  loop: "{{ server_list }}"

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- set_fact:
    server_list: "{{ server_list | map('combine', {'ports': item.ports}) }}"
  loop: "{{ server_list }}"