An Ansible plugin that builds an inventory from the output of 'getent hosts' on a remote machine

remote_hosts.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

import socket
import subprocess
from ansible.plugins.inventory import BaseInventoryPlugin

DOCUMENTATION = r'''
    name: remote_hosts
    plugin_type: inventory
    short_description: Returns an Ansible inventory from 'getent hosts'
    description:
      - Generate an inventory by connecting to a remote machine using ssh
      - and running 'getent hosts'.
      - The returned inventory is grouped into a 'xxx_hosts' group, where xxx
      - is the remote_hostname. We assume that 'ssh' is on the path, and
      - the system is able to connect using passwordless auth.
    options:
      plugin:
          description: getent hosts inventory
          required: true
      remote_hostname:
        description: The remote machine on which to run 'getent hosts'.
        required: true
      remote_user:
        description:
          - The user to connect to the remote machine as.
          - If left empty, we connect as the current user.
        required: false
    author: Tim Foster @timfoster
'''

#
# For example:
# $ /bin/ls ~/.ansible/plugins/inventory/remote_hosts.py
# /Users/timf/.ansible/plugins/inventory/remote_hosts.py
#
# $ cat remote_inv.yml
# plugin: remote_hosts
# remote_hostname: puroto
#
# $ ansible-inventory -i remote_inv.yml  --graph
# @all:
#  |--@puroto_hosts:
#  |  |--LB2120.mhs
#  |  |--aeris
#  |  |--amiorangi
#  |  |--ampache
#  |  |--aratuku
#  etc.
#

class InventoryModule(BaseInventoryPlugin):

    NAME = 'remote_hosts'

    def verify_file(self, path):
        # This is really basic
        if path.endswith(".yaml") or path.endswith(".yml"):
            return True
        return False

    def parse(self, inventory, loader, path, cache=True):
        super(InventoryModule, self).parse(inventory, loader, path, cache)
        self.inventory = inventory
        self.loader = loader
        self.path = path
        self.cache = cache

        config = self._read_config_data(path)
        remote_host = config.get("remote_hostname")
        remote_user = config.get("remote_user")
        if not remote_host:
            raise Exception("Missing 'remote_hostname' configuration")

        try:
            socket.gethostbyname(remote_host)
        except Exception as e:
            raise Exception("Unable to reach %s: %s" % (s, e))

        group = "%s_hosts" % remote_host
        self.inventory.add_group(group)

        if remote_user:
            ssh_cmd = "ssh -l %s %s getent hosts" % (remote_user, remote_host)
        else:
            ssh_cmd = "ssh %s getent hosts" % remote_host

        completed = subprocess.run(ssh_cmd.split(), capture_output=True)
        if completed.returncode != 0:
            raise Exception("Unable to run command: %s" % ssh_cmd)

        for line in completed.stdout.decode().split('\n'):
            if not line:
                continue
            address, hosts = line.split(maxsplit=1)
            for host in hosts.split():
                self.inventory.add_host(host.strip(), group)