ansible-later/docs/content/build_rules/rule.md

title
Write a rule

A typical rule check will look like:

{{< highlight Python "linenos=table" >}} class CheckBecomeUser(RuleBase):

sid = "ANSIBLE0015"
description = "Become should be combined with become_user"
helptext = "the task has `become` enabled but `become_user` is missing"
types = ["playbook", "task", "handler"]

def check(self, candidate, settings):
    tasks, errors = self.get_normalized_tasks(candidate, settings)
    true_value = [True, "true", "True", "TRUE", "yes", "Yes", "YES"]

    if not errors:
        gen = (task for task in tasks if "become" in task)
        for task in gen:
            if task["become"] in true_value and "become_user" not in task.keys():
                errors.append(self.Error(task["__line__"], self.helptext))

    return self.Result(candidate.path, errors)

{{< /highlight >}}

They return a Result object, which contains a possibly empty list of Error objects. Error objects are formed of a line number and a message. If the error applies to the whole file being reviewed, set the line number to None.