Ansible task to fix `Plugin 'unix_socket' is not loaded` on MariaDB

fix_unix_socket.yml

---
- name: Enable plugin unix_socket
  command: mysql --defaults-file=/etc/mysql/debian.cnf -e "INSTALL PLUGIN unix_socket SONAME 'auth_socket'"
  register: mysql_result
  changed_when: mysql_result.rc == 0
  failed_when: mysql_result.rc != 0 and 'already installed' not in mysql_result.stderr

Thanks @corny

This is what worked for me:

---
- name: Load auth_socket plugin
  ini_file:
    path: /etc/mysql/mariadb.cnf
    section: mysqld
    option: plugin-load-add
    value: auth_socketo.so
  register: auth_socket_loaded

- service: name=mysql state=restarted enabled=yes
  when: auth_socket_loaded.changed