lineinfile

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

# (c) 2012, Daniel Hokka Zakrisson <daniel@hozac.com>
#
# 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/>.

import re
import os

DOCUMENTATION = '''
---
module: lineinfile
author: Daniel Hokka Zakrisson
short_description: Ensure a particular line is in a file
description:
  - This module will search a file for a line, and ensure that it is present or absent.
  - This is primarily useful when you want to change a single line in a
    file only. For other cases, see the M(copy) or M(template) modules.
version_added: "0.7"
options:
  dest:
    required: true
    aliases: [ name, destfile ]
    description:
      - The file to modify
  regexp:
    required: true
    description:
      - The regular expression to look for in the file. For C(state=present),
        the pattern to replace. For C(state=absent), the pattern of the line
        to remove.
  state:
    required: false
    choices: [ present, absent ]
    default: "present"
    aliases: []
    description:
      - Whether the line should be there or not.
  line:
    required: false
    description:
      - Required for C(state=present). The line to insert/replace into the
        file. Must match the value given to C(regexp).
  insertafter:
    required: false
    default: EOF
    description:
      - Used with C(state=present). If specified, the line will be inserted
        after the specified regular expression. Two special values are
        available; C(BOF) for inserting the line at the beginning of the
        file, and C(EOF) for inserting the line at the end of the file.
    choices: [ BOF, EOF ]
    default: EOF
  backup:
     required: false
     default: no
     description:
       - Create a backup file including the timestamp information so you can
         get the original file back if you somehow clobbered it incorrectly.
examples:
   - code: lineinfile dest=/etc/selinux/config regexp=^SELINUX= line=SELINUX=disabled
   - code: lineinfile dest=/etc/sudoers state=absent regexp="^%wheel"
'''

def present(module, dest, regexp, line, insertafter, backup):
    f = open(dest, 'rb')
    lines = f.readlines()
    f.close()

    mre = re.compile(regexp)
    if not mre.search(line):
        module.fail_json(msg="usage error: line= doesn't match regexp (%s)" % regexp)

    if insertafter in ('BOF', 'EOF'):
        iare = None
    else:
        iare = re.compile(insertafter)

    index = [-1, -1]
    for lineno in range(0, len(lines)):
        if mre.search(lines[lineno]):
            index[0] = lineno
        elif iare is not None and iare.search(lines[lineno]):
            # + 1 for the next line
            index[1] = lineno + 1

    # Regexp matched a line in the file
    if index[0] != -1:
        if lines[index[0]] == line + os.linesep:
            msg = ''
            changed = False
        else:
            lines[index[0]] = line + os.linesep
            msg = 'line replaced'
            changed = True
    # Add it to the beginning of the file
    elif insertafter == 'BOF':
        lines.insert(0, line + os.linesep)
        msg = 'line added'
        changed = True
    # Add it to the end of the file if requested or if insertafter= didn't match
    elif insertafter == 'EOF' or index[1] == -1:
        lines.append(line + os.linesep)
        msg = 'line added'
        changed = True
    # insertafter= matched
    else:
        lines.insert(index[1], line + os.linesep)
        msg = 'line added'
        changed = True

    if changed:
        if backup:
            module.backup_local(dest)
        f = open(dest, 'wb')
        f.writelines(lines)
        f.close()

    module.exit_json(changed=changed, msg=msg)

def absent(module, dest, regexp, backup):
    f = open(dest, 'rb')
    lines = f.readlines()
    f.close()
    cre = re.compile(regexp)
    found = []
    def matcher(line):
        if cre.search(line):
            found.append(line)
            return False
        else:
            return True
    lines = filter(matcher, lines)
    changed = len(found) > 0
    if changed:
        if backup:
            module.backup_local(dest)
        f = open(dest, 'wb')
        f.writelines(lines)
        f.close()
    module.exit_json(changed=changed, found=len(found))

def main():
    module = AnsibleModule(
        argument_spec = dict(
            dest=dict(required=True, aliases=['name', 'destfile']),
            state=dict(default='present', choices=['absent', 'present']),
            regexp=dict(required=True),
            line=dict(aliases=['value']),
            insertafter=dict(default='EOF'),
            backup=dict(default=False, choices=BOOLEANS),
        ),
    )

    params = module.params
    backup = module.boolean(module.params.get('backup', False))

    if params['state'] == 'present':
        if 'line' not in params:
            module.fail_json(msg='line= is required with state=present')
        present(module, params['dest'], params['regexp'], params['line'],
                params['insertafter'], backup)
    else:
        absent(module, params['dest'], params['regexp'], backup)

# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>

main()