send a welcome message from ansible

filters_plugins.py

import yaml

class FilterModule(object):
    def filters(self):
        return {
            'nice_yaml': lambda *a, **kw: yaml.safe_dump(*a, indent=4, default_flow_style=False, **kw),
        }

welcome-message.yaml

---
- hosts: ${hosts}
  tasks:
    - mail: to=...
      args:
        from: root@$ansible_fqdn
        body: $TEMPLATE(welcome.j2)
        subject: welcome to $ansible_fqdn

welcome.j2

Hi, I'm your new server!

My name is {{ ansible_fqdn }}.

RSA Host Key
------------
{{ ansible_ssh_host_key_rsa_public|nice_yaml }}

IPv4
----
{{ ansible_default_ipv4|nice_yaml }}

IPv6
----
{{ ansible_default_ipv6|nice_yaml }}

Hardware
------
{{ ansible_processor|nice_yaml }}

{{ ansible_devices|nice_yaml }}