ansible/system/host

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# (c) 2013, René Moser <mail@renemoser.net>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.

DOCUMENTATION = '''
---
module: host
author: René Moser
version_added: "1.3"
short_description: Add or remove entries in /etc/hosts
requirements:
description:
    - Manage entries in /etc/hosts
options:
    ip:
        required: false
        description:
            - IP address. Required on state "present".
    hostname:
        required: false
        description:
            - name of host. Required on state "present".
    aliases:
        required: false
        description:
            - list of alias hostnames, comma separated.
    state:
        required: false
        default: "present"
        choices: [ present, absent ]
        description:
            - Whether the entries should be present or not in /etc/hosts.
'''

EXAMPLES = '''
# Example host command from Ansible Playbooks
- host: ip=127.0.0.1 hostname=localhost aliases=foobar.com,localhost.foobar.com
- host: ip=127.0.0.1 hostname=localhost state=present
- host: ip=192.168.1.1 state=absent
- host: hostname=localhost state=absent
- host: ip=::1 hostname=localhost aliases=ip6-localhost,ip6-loopback
'''

import os
import tempfile
import fileinput
import syslog

class Host(object):

    HOSTSFILE = '/etc/hosts'

    def __init__(self, module):
        self.module             = module
        self.state              = module.params['state']
        self.ip                 = module.params['ip']
        self.hostname           = module.params['hostname']
        self.aliases            = module.params['aliases']
        self.changed            = False
        self.ip_matches         = False
        self.hostname_matches   = False
        self.aliases_matches    = False
        self.has_aliases        = False
        self.found_on_line      = -1
        self.syslogging         = False

    def validate_has_hostname_on_present(self):
        err = ''
        if self.state == 'present' and not (self.hostname and self.ip):
            err = "Error: No param 'hostnames' or 'ip' given in state 'present'."
        return err

    def validate_has_ip_or_hostname_on_absent(self):
        err = ''
        if self.state == 'absent':
            if not (self.hostname or self.ip):
                err = "Error: Either param 'hostnames' or 'ip' must be given in state 'absent'."
            if self.hostname and self.ip:
                err = "Error: Either param 'hostnames' or 'ip' must be given in state 'absent'."
        return err

    def log(self, msg):
        if self.syslogging:
            syslog.openlog('ansible-%s' % os.path.basename(__file__))
            syslog.syslog(syslog.LOG_NOTICE, '' + msg)

    def proceed_hosts_entries(self):

        f = open(self.HOSTSFILE,'rb')
        self.lines = f.readlines()
        f.close()

        for lineno, line in enumerate(self.lines):
            if line.startswith("#"):
                continue

            ip = line.split()[0:1]
            hostname = line.split()[1:2]
            aliases = ','.join(line.split()[2:])

            if self.ip and self.ip in ip: 
                self.ip_matches = True
                self.found_on_line = lineno
                self.log(self.ip + ' found on line')

            if self.hostname and self.hostname in hostname:
                self.hostname_matches = True
                self.found_on_line = lineno
                self.log(self.hostname + ' found on line')

            # only look at aliases if we found hostname or ip
            if self.hostname_matches or self.ip_matches:
                if aliases:
                    self.log('aliases: ' + aliases)
                    self.has_aliases = True
                if self.aliases and self.aliases == aliases:
                    self.aliases_matches = True
                break

    def full_entry_exists(self):
        if self.has_aliases and not self.aliases_matches:
            return False
        return self.ip_matches and self.hostname_matches

    def entry_exists(self):
        return self.ip_matches or self.hostname_matches

    def remove_entry(self):
        self.lines.pop(self.found_on_line)

    def add_entry(self):
        aliases = ''
        if self.aliases:
            aliases = self.aliases.replace(',',' ')
        host_entry =  self.ip + " " + self.hostname + " " + aliases + "\n"
        if self.entry_exists():
            self.lines[self.found_on_line] = host_entry
        else:
            self.lines.extend(host_entry)

    def write_changes(self):
        tmpfd, tmpfile = tempfile.mkstemp()
        f = os.fdopen(tmpfd,'wb')
        f.writelines(self.lines)
        f.close()
        self.module.atomic_move(tmpfile, self.HOSTSFILE)
        self.changed = True

def main():
    module = AnsibleModule(
        argument_spec = dict(
            state=dict(default='present', choices=['present', 'absent'], type='str'),
            ip=dict(default=None, type='str'),
            hostname=dict(default=None, type='str'),
            aliases=dict(default=None, type='str'),
        ),
        supports_check_mode=True
    )

    result = {}
    host = Host(module)
    result['state'] = host.state

    err = host.validate_has_hostname_on_present()
    if err:
        module.fail_json(msg=err)

    err = host.validate_has_ip_or_hostname_on_absent()
    if err:
        module.fail_json(msg=err)

    host.proceed_hosts_entries()
    if host.state == 'present':
        if not host.full_entry_exists():
            host.log('Entry does not fully exist or may be missing.')
            if module.check_mode:
                module.exit_json(changed=True)
            host.log('Adding or replacing entry.')
            host.add_entry()
            host.write_changes()

    elif host.state == 'absent':
        if host.entry_exists():
            host.log('IP entry exists, removing.')
            if module.check_mode:
                module.exit_json(changed=True)
            host.remove_entry()
            host.write_changes()

    result['changed'] = host.changed
    module.exit_json(**result)

# include magic from lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()