"Error establishing a database connection" ao acessar via browse o IP 172.17.177.40. provisioning.yml executado com sucesso.

---
- hosts: database
  handlers:
    - name: restart mysql
      service:
        name: mysql
        state: restarted
      become: yes
  tasks:
  - name: 'Instala pacotes de dependencia do sistema operacional'
    apt:
      update_cache: yes
      cache_valid_time: 3600 #1 hora
      name:
          - mysql-server
          - python-mysqldb
      state: latest
    become: yes

  - name: 'Cria o banco no MySQL'
    mysql_db:
      login_user: root
      name: "{{ wp_db_name }}"
      state: present
    become: yes

  - name: 'Cria o usuário do MySQL'
    mysql_user:
      login_user: root
      name: "{{wp_username}}"
      password: "{{wp_user_password}}"
      priv: "{{wp_db_name}}.*:ALL"
      state: present
      host: "{{ item }}"
    loop:
      - 'localhost'
      - '127.0.0.1'
      - "{{ wp_host_ip }}"
    become: yes

  - name: 'Configura MySQL para aceitar conexões remotas'
    copy:
      src: 'files/my.cnf'
      dest: '/etc/mysql/my.cnf'
    become: yes
    notify:
        - restart mysql

- hosts: wordpress
  handlers:
     - name: restart apache
       service:
         name: apache2
         state: restarted
  become: yes

  tasks:
    - name: 'Instala pacotes de dependencia do sistema operacional'
      apt:
        update_cache: yes
        cache_valid_time: 3600 #1 hora
        name:
            - php7.2
            - apache2
            - libapache2-mod-php7.2
            - php7.2-gd
            - php-ssh2
            - php7.2-mysql
        state: latest
      become: yes

    - name: 'Baixa o arquivo de instalacao do Wordpress'
      get_url:
        url: 'https://wordpress.org/latest.tar.gz'
        dest: '/tmp/wordpress.tar.gz'
        mode: 0440

    - name: 'Descompacta o Wordpress'
      unarchive:
        src: '/tmp/wordpress.tar.gz'
        dest: '/var/www/'
        remote_src: yes
      become: yes

    - copy:
        src: "{{ wp_installation_dir }}/wp-config-sample.php"
        dest: "{{ wp_installation_dir }}/wp-config.php"
        remote_src: yes
      become: yes

    - name: 'Configura o wp-config com as entradas do banco de dados'
      replace:
        path: "{{ wp_installation_dir }}/wp-config.php"
        regexp: "{{ item.regex }}"
        replace: "{{ item.value }}"
      loop:
            - { regex: 'database_name_here', value: "{{wp_db_name}}"}
            - { regex: 'username_here', value: "{{wp_username}}"}
            - { regex: 'password_here', value: "{{wp_user_password}}"}
            - { regex: 'localhost', value: "{{wp_db_ip}}"}
      become: yes

    - name: 'Configura Apache para servir Wordpress'
      template:
        src: 'templates/000-default.conf.j2'
        dest: '/etc/apache2/sites-available/000-default.conf'
      become: yes
      notify:
        - restart apache

arquivo all.yml
---
  wp_db_name: wordpress_db
  wp_user_password: 12345
  wp_username: zick
  wp_installation_dir: '/var/www/wordpress'

arquivo database.yml
---
  wp_host_ip: '172.17.177.40'

arquivo wordpress.yml
---
  wp_db_ip: '172.17.177.42'