Find ansible ssh user

Question

I'm using the User in ~/.ssh/config file to specify the user name ansible uses to access the remote server, for example:

Host 123.234.098.076
  User my_local_user_name

Is there a way to find that user name in Ansible? In the following playbook ansible_user is defined:

---
- hosts: "all"
  tasks:
    - name: "perform whoami"
      shell: whoami
      register: whoami
    - set_fact:
        ansible_user: "{{ whoami.stdout }}"
    - debug:
        msg: "I am user: {{ ansible_user }}"  # will display: "I am user: my_local_user_name"

However I'm not sure of any unintended consequences of setting the ansible_user directly as opposed to using the remote_user setting in the playbook, in the inventory or in the ansible config such as:

---
- hosts: "all"
  remote_user: my_local_user_name
  tasks:
    #- name: "perform whoami"
    #  shell: whoami
    #  register: whoami
    #- set_fact:
    #    ansible_user: "{{ whoami.stdout }}"
    - debug:
        msg: "I am user: {{ ansible_user }}"  # will display: "I am user: my_local_user_name"

Answer 1

If you need to get ssh user after connection has been made and facts about target host are available, you can use ansible_user_id fact.

If you want to know ssh user before connection has been made, here is a trick:

---
- hosts: all
  gather_facts: no
  tasks:
    - name: Save our destination host
      set_fact: dest_host="{{ ansible_host }}"

    - name: Get user from local ssh config
      local_action: shell ssh -G {{ dest_host }} | awk '/^user /{ print $2 }'
      changed_when: false
      register: ssh_user

    - name: Print forced ansible_user if defined or username from ssh config otherwize
      debug: msg="Ansible will connect with {{ ansible_user | default(ssh_user.stdout) }}"

- hosts: all
  gather_facts: yes
  tasks:
    - name: Print our remote name
      debug: msg="Ansible connected with {{ ansible_user_id }}"

Not sure if ssh -G is available on every system.

If you don't specify remote_user in Ansible playbook or inventory, it relies on ssh to make the connection, so the only way to know username is to parse ssh config files, where -G option comes in handy.