Ansible error stating: 'apt_repository' is not a valid attribute for a Play [duplicate]

Answer 1

You try to run tasks list as a playbook.

To make it work, write a simple playbook:

- hosts: all
  tasks:
    - include: roles/java/tasks/debian.yml

Answer 2

Your input

- name: Setup oracle java deb repo
   apt_repository:
     repo: "ppa:webupd8team/java"
     update_cache: yes

is invalid YAML.

This is correct (value for name is a scalar spread over multiple lines):

- name: Setup oracle java deb repo
   apt_repository
     repo "ppa:webupd8team/java"
     update_cache yes

And this is correct as well (proper indentation at 2 indents):

- name: Setup oracle java deb repo
  apt_repository:
    repo: "ppa:webupd8team/java"
    update_cache: yes

You probably want the later.