Install openwisp2 ubuntu 18.04.4

[Rental Net]

hello everyone, I try to install openwisp2 in ubuntu so after installation it throws me the following error 

fatal: [192.168.10.97]: FAILED! => {"changed": true, "cmd": ["/usr/sbin/postmap"           , "/etc/postfix/generic"], "delta": "0:00:01.010549", "end": "2019-10-22 01:08:5           4.446612", "msg": "non-zero return code", "rc": 1, "start": "2019-10-22 01:08:53           .436063", "stderr": "postmap: warning: valid_hostname: numeric hostname: 192.168           .10.97\npostmap: fatal: file /etc/postfix/main.cf: parameter myhostname: bad par           ameter value: 192.168.10.97", "stderr_lines": ["postmap: warning: valid_hostname           : numeric hostname: 192.168.10.97", "postmap: fatal: file /etc/postfix/main.cf:            parameter myhostname: bad parameter value: 192.168.10.97"], "stdout": "", "stdou           t_lines": []}

[Daniel Wang]

Hello,

It is highly recommended for production servers to use a publicly accessible FQDN (for example: openwisp2.mydomain.com) as the hostname in the Ansible inventory file. This is needed to send emails properly.

If you are installing for development, you can bypass this error by adding postfix_myhostname: localhost as one of the vars in playbook.yml.

Regards,

Daniel