How to get the list of authorized_keys of a given user?

I want to write a ansible playbook where we can provide a username and ansible will display the authorized keys for that user. The path to the authorized keys is {{user_home_dir}}/.ssh/authorized_keys.

I tried with shell module like below:

---
- name: Get authorized_keys 
  shell: cat "{{ user_home_dir }}"/.ssh/authorized_keys
  register: read_key

- name: Prints out authorized_key 
  debug: var=read_key.stdout_lines

The problem is, it will show me the file inside /home/ansible/.ssh/authorized_keys. "ansible" is the user that I am using to connect to remote machine.

Below is vars/main.yml

---
authorized_user: username
user_home_dir: "{{ lookup('env','HOME') }}"

Any idea? FYI I am new to ansible and tried this link already.

Solution

Below worked. We need to have become too otherwise we will get permission denied error.

---
- hosts: local
  remote_user: ansible
  gather_facts: no
  become: yes
  become_method: sudo

  vars:
    username: myuser

  tasks:

    - name: get user info
      getent:
        split: ":"
        database: passwd
        key: "{{ username }}"

    - name: Get authorized_keys
      shell: cat "{{ getent_passwd[username][4]  }}"/.ssh/authorized_keys
      register: read_key

    - name: Prints out authorized_key
      debug: var=read_key.stdout_lines