#!/usr/bin/python # -*- coding: utf-8 -*- """ Ansible module to manage symbolic link alternatives. (c) 2014, Gabe Mulley (c) 2015, David Wittman 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 . """ DOCUMENTATION = ''' --- module: alternatives short_description: Manages alternative programs for common commands description: - Manages symbolic links using the 'update-alternatives' tool - Useful when multiple programs are installed but provide similar functionality (e.g. different editors). version_added: "1.6" author: - "David Wittman (@DavidWittman)" - "Gabe Mulley (@mulby)" options: name: description: - The generic name of the link. required: true path: description: - The path to the real executable that the link should point to. required: true link: description: - The path to the symbolic link that should point to the real executable. - This option is required on RHEL-based distributions required: false priority: description: - The priority of the alternative required: false requirements: [ update-alternatives ] ''' EXAMPLES = ''' - name: correct java version selected alternatives: name=java path=/usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java - name: alternatives link created alternatives: name=hadoop-conf link=/etc/hadoop/conf path=/etc/hadoop/conf.ansible - name: make java 32 bit an alternative with low priority alternatives: name=java path=/usr/lib/jvm/java-7-openjdk-i386/jre/bin/java priority=-10 ''' import re from ansible.module_utils.basic import * from ansible.module_utils.pycompat24 import get_exception def main(): module = AnsibleModule( argument_spec = dict( name = dict(required=True), path = dict(required=True, type='path'), link = dict(required=False, type='path'), priority = dict(required=False, type='int', default=50), ), supports_check_mode=True, ) params = module.params name = params['name'] path = params['path'] link = params['link'] priority = params['priority'] UPDATE_ALTERNATIVES = module.get_bin_path('update-alternatives',True) current_path = None all_alternatives = [] # Run `update-alternatives --display ` to find existing alternatives (rc, display_output, _) = module.run_command( ['env', 'LC_ALL=C', UPDATE_ALTERNATIVES, '--display', name] ) if rc == 0: # Alternatives already exist for this link group # Parse the output to determine the current path of the symlink and # available alternatives current_path_regex = re.compile(r'^\s*link currently points to (.*)$', re.MULTILINE) alternative_regex = re.compile(r'^(\/.*)\s-\spriority', re.MULTILINE) current_path = current_path_regex.search(display_output).group(1) all_alternatives = alternative_regex.findall(display_output) if not link: # Read the current symlink target from `update-alternatives --query` # in case we need to install the new alternative before setting it. # # This is only compatible on Debian-based systems, as the other # alternatives don't have --query available rc, query_output, _ = module.run_command( ['env', 'LC_ALL=C', UPDATE_ALTERNATIVES, '--query', name] ) if rc == 0: for line in query_output.splitlines(): if line.startswith('Link:'): link = line.split()[1] break if current_path != path: if module.check_mode: module.exit_json(changed=True, current_path=current_path) try: # install the requested path if necessary if path not in all_alternatives: if not link: module.fail_json(msg="Needed to install the alternative, but unable to do so as we are missing the link") module.run_command( [UPDATE_ALTERNATIVES, '--install', link, name, path, str(priority)], check_rc=True ) # select the requested path module.run_command( [UPDATE_ALTERNATIVES, '--set', name, path], check_rc=True ) module.exit_json(changed=True) except subprocess.CalledProcessError: e = get_exception() module.fail_json(msg=str(dir(cpe))) else: module.exit_json(changed=False) main()