Installing cert-manager for Kubernetes via Ansible gives ModuleNotFoundError

I am writing an Ansible playbook to build a Kubernetes cluster (K3S) running on 4 nodes with Raspi OS.

I am using the kubernetes.core package that can be installed in Ansible with the command:

ansible-galaxy collection install kubernetes.core

The API is found here.

I am trying to install the cert-manager repository to Helm with a task that is analogue to the command:

helm repo add jetstack https://charts.jetstack.io --force-update

And so far I have defined the task as:

- name: Add cert-manager Helm repository
  kubernetes.core.helm_repository:
    name: jetstack
    url: https://charts.jetstack.io
    force: true

But when I run my playbook I get the following error:

TASK [helm : Add cert-manager Helm repository]
***************************************************
An exception occurred during task execution. To see
the full traceback, use -vvv. The error was: 
ModuleNotFoundError: No module named 'yaml'

Adding -vvv gives a little more information, but still rather obscure:

The full traceback is:

Traceback (most recent call last):
  File "/tmp/ansible_kubernetes.core.helm_repository_payload_tdbnu9cy/ansible_kubernetes.core.helm_repository_payload.zip/ansible_collections/kubernetes/core/plugins/modules/helm_repository.py", line 173, in <module>
ModuleNotFoundError: No module named 'yaml'

Is there anyone who knows what is going on?

Solution

Some modules in Ansible have external dependencies which you might need t installed them on either target node or controller node(This depends on where it will going to be used). To check module dependencies, by convention, they have REQUIREMENTS field which you can check by using something like grep or awk:

ansible-doc kubernetes.core.helm_repository | awk '/REQUIREMENTS/,/^$/'

Example:

~> ansible-doc kubernetes.core.helm_repository |  awk  '/REQUIREMENTS/,/^$/'
REQUIREMENTS:  helm (https://github.com/helm/helm/releases), yaml
        (https://pypi.org/project/PyYAML/)


~> ansible-doc community.mysql.mysql_db |  awk  '/REQUIREMENTS/,/^$/'
REQUIREMENTS:  MySQLdb (Python 2.x), PyMySQL (Python 2.7 and Python
        3.x) or, mysql (command line binary),
        mysqlclient (Python 3.5+) or, mysqldump
        (command line binary)

keep in mind, not all of them always needed. for instance in mysql example its enough to have either of MySQLdb or PyMySQL. sometimes a dependency is used in a specific kind of task too. like mysqldump would be used just if you want to create dumps using mysql Ansible module, otherwise you don't need it.