Add the cronvar module.

This manages environment variables in Vixie crontabs.  It includes
addition/removal/replacement of variables and ordering via the
insertbefore/insertafter parameters.

lib/ansible/modules/extras/system/cronvar.py

@@ -0,0 +1,430 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+#
+# 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/>.
+#
+# Cronvar Plugin: The goal of this plugin is to provide an indempotent
+# method for set cron variable values.  It should play well with the
+# existing cron module as well as allow for manually added variables.
+# Each variable entered will be preceded with a comment describing the
+# variable so that it can be found later.  This is required to be
+# present in order for this plugin to find/modify the variable
+#
+# This module is based on the crontab module.
+#
+
+DOCUMENTATION = """
+---
+module: cronvar
+short_description: Manage variables in crontabs
+description:
+  - Use this module to manage crontab variables. This module allows
+    you to create, update, or delete cron variable definitions.
+version_added: "2.0"
+options:
+  name:
+    description:
+      - Name of the crontab variable.
+    default: null
+    required: true
+  value:
+    description:
+      - The value to set this variable to.  Required if state=present.
+    required: false
+    default: null
+  insertafter:
+    required: false
+    default: null
+    description:
+      - Used with C(state=present). If specified, the variable will be inserted
+        after the variable specified.
+  insertbefore:
+    required: false
+    default: null
+    description:
+      - Used with C(state=present). If specified, the variable will be inserted
+        just before the variable specified.
+  state:
+    description:
+      - Whether to ensure that the variable is present or absent.
+    required: false
+    default: present
+    choices: [ "present", "absent" ]
+  user:
+    description:
+      - The specific user whose crontab should be modified.
+    required: false
+    default: root
+  cron_file:
+    description:
+      - If specified, uses this file in cron.d instead of an individual user's crontab.
+    required: false
+    default: null
+  backup:
+    description:
+      - If set, create a backup of the crontab before it is modified.
+        The location of the backup is returned in the C(backup) variable by this module.
+    required: false
+    default: false
+requirements:
+  - cron
+author: Doug Luce
+"""
+
+EXAMPLES = '''
+# Ensure a variable exists.
+# Creates an entry like "EMAIL=doug@ansibmod.con.com"
+- cronvar: name="EMAIL" value="doug@ansibmod.con.com"
+
+# Make sure a variable is gone.  This will remove any variable named
+# "LEGACY"
+- cronvar: name="LEGACY" state=absent
+
+# Adds a variable to a file under /etc/cron.d
+- cronvar: name="LOGFILE" value="/var/log/yum-autoupdate.log"
+        user="root" cron_file=ansible_yum-autoupdate
+'''
+
+import os
+import re
+import tempfile
+import platform
+import pipes
+import shlex
+
+CRONCMD = "/usr/bin/crontab"
+
+class CronVarError(Exception):
+    pass
+
+class CronVar(object):
+    """
+        CronVar object to write variables to crontabs.
+
+        user      - the user of the crontab (defaults to root)
+        cron_file - a cron file under /etc/cron.d
+    """
+    def __init__(self, module, user=None, cron_file=None):
+        self.module = module
+        self.user = user
+        if self.user is None:
+            self.user = 'root'
+        self.lines = None
+        self.wordchars = ''.join(chr(x) for x in range(128) if chr(x) not in ('=', "'", '"', ))
+        # select whether we dump additional debug info through syslog
+        self.syslogging = False
+
+        if cron_file:
+            self.cron_file = '/etc/cron.d/%s' % cron_file
+        else:
+            self.cron_file = None
+
+        self.read()
+
+    def read(self):
+        # Read in the crontab from the system
+        self.lines = []
+        if self.cron_file:
+            # read the cronfile
+            try:
+                f = open(self.cron_file, 'r')
+                self.lines = f.read().splitlines()
+                f.close()
+            except IOError, e:
+                # cron file does not exist
+                return
+            except:
+                raise CronVarError("Unexpected error:", sys.exc_info()[0])
+        else:
+            # using safely quoted shell for now, but this really should be two non-shell calls instead.  FIXME
+            (rc, out, err) = self.module.run_command(self._read_user_execute(), use_unsafe_shell=True)
+
+            if rc != 0 and rc != 1: # 1 can mean that there are no jobs.
+                raise CronVarError("Unable to read crontab")
+
+            lines = out.splitlines()
+            count = 0
+            for l in lines:
+                if count > 2 or (not re.match( r'# DO NOT EDIT THIS FILE - edit the master and reinstall.', l) and
+                                 not re.match( r'# \(/tmp/.*installed on.*\)', l) and
+                                 not re.match( r'# \(.*version.*\)', l)):
+                    self.lines.append(l)
+                count += 1
+
+    def log_message(self, message):
+        if self.syslogging:
+            syslog.syslog(syslog.LOG_NOTICE, 'ansible: "%s"' % message)
+
+    def write(self, backup_file=None):
+        """
+        Write the crontab to the system. Saves all information.
+        """
+        if backup_file:
+            fileh = open(backup_file, 'w')
+        elif self.cron_file:
+            fileh = open(self.cron_file, 'w')
+        else:
+            filed, path = tempfile.mkstemp(prefix='crontab')
+            fileh = os.fdopen(filed, 'w')
+
+        fileh.write(self.render())
+        fileh.close()
+
+        # return if making a backup
+        if backup_file:
+            return
+
+        # Add the entire crontab back to the user crontab
+        if not self.cron_file:
+            # quoting shell args for now but really this should be two non-shell calls.  FIXME
+            (rc, out, err) = self.module.run_command(self._write_execute(path), use_unsafe_shell=True)
+            os.unlink(path)
+
+            if rc != 0:
+                self.module.fail_json(msg=err)
+
+    def remove_variable_file(self):
+        try:
+            os.unlink(self.cron_file)
+            return True
+        except OSError, e:
+            # cron file does not exist
+            return False
+        except:
+            raise CronVarError("Unexpected error:", sys.exc_info()[0])
+
+    def parse_for_var(self, line):
+        lexer = shlex.shlex(line)
+        lexer.wordchars = self.wordchars
+        varname = lexer.get_token()
+        is_env_var = lexer.get_token() == '='
+        value = ''.join(lexer)
+        if is_env_var:
+            return (varname, value)
+        raise CronVarError("Not a variable.")
+
+    def find_variable(self, name):
+        comment = None
+        for l in self.lines:
+            try:
+                (varname, value) = self.parse_for_var(l)
+                if varname == name:
+                    return value
+            except CronVarError:
+                pass
+        return None
+
+    def get_var_names(self):
+        var_names = []
+        for l in self.lines:
+            try:
+                (var_name, _) = self.parse_for_var(l)
+                var_names.append(var_name)
+            except CronVarError:
+                pass
+        return var_names
+
+    def add_variable(self, name, value, insertbefore, insertafter):
+        if insertbefore is None and insertafter is None:
+            # Add the variable to the top of the file.
+            self.lines.insert(0, "%s=%s" % (name, value))
+        else:
+            newlines = []
+            for l in self.lines:
+                try:
+                    (varname, _) = self.parse_for_var(l) # Throws if not a var line
+                    if varname == insertbefore:
+                        newlines.append("%s=%s" % (name, value))
+                        newlines.append(l)
+                    elif varname == insertafter:
+                        newlines.append(l)
+                        newlines.append("%s=%s" % (name, value))
+                    else:
+                        raise CronVarError # Append.
+                except CronVarError:
+                    newlines.append(l)
+
+            self.lines = newlines
+
+    def remove_variable(self, name):
+        self.update_variable(name, None, remove=True)
+
+    def update_variable(self, name, value, remove=False):
+        newlines = []
+        for l in self.lines:
+            try:
+                (varname, _) = self.parse_for_var(l) # Throws if not a var line
+                if varname != name:
+                    raise CronVarError # Append.
+                if not remove:
+                    newlines.append("%s=%s" % (name, value))
+            except CronVarError:
+                newlines.append(l)
+
+        self.lines = newlines
+
+    def render(self):
+        """
+        Render a proper crontab
+        """
+        result = '\n'.join(self.lines)
+        if result and result[-1] not in ['\n', '\r']:
+            result += '\n'
+        return result
+
+    def _read_user_execute(self):
+        """
+        Returns the command line for reading a crontab
+        """
+        user = ''
+
+        if self.user:
+            if platform.system() == 'SunOS':
+                return "su %s -c '%s -l'" % (pipes.quote(self.user), pipes.quote(CRONCMD))
+            elif platform.system() == 'AIX':
+                return "%s -l %s" % (pipes.quote(CRONCMD), pipes.quote(self.user))
+            elif platform.system() == 'HP-UX':
+                return "%s %s %s" % (CRONCMD , '-l', pipes.quote(self.user))
+            else:
+                user = '-u %s' % pipes.quote(self.user)
+        return "%s %s %s" % (CRONCMD , user, '-l')
+
+    def _write_execute(self, path):
+        """
+        Return the command line for writing a crontab
+        """
+        user = ''
+        if self.user:
+            if platform.system() in ['SunOS', 'HP-UX', 'AIX']:
+                return "chown %s %s ; su '%s' -c '%s %s'" % (pipes.quote(self.user), pipes.quote(path), pipes.quote(self.user), CRONCMD, pipes.quote(path))
+            else:
+                user = '-u %s' % pipes.quote(self.user)
+        return "%s %s %s" % (CRONCMD , user, pipes.quote(path))
+
+#==================================================
+
+def main():
+    # The following example playbooks:
+    #
+    # - cronvar: name="SHELL" value="/bin/bash"
+    #
+    # - name: Set the email
+    #   cronvar: name="EMAILTO" value="doug@ansibmod.con.com"
+    #
+    # - name: Get rid of the old new host variable
+    #   cronvar: name="NEW_HOST" state=absent
+    #
+    # Would produce:
+    # SHELL = /bin/bash
+    # EMAILTO = doug@ansibmod.con.com
+
+    module = AnsibleModule(
+        argument_spec=dict(
+            name=dict(required=True),
+            value=dict(required=False),
+            user=dict(required=False),
+            cron_file=dict(required=False),
+            insertafter=dict(default=None),
+            insertbefore=dict(default=None),
+            state=dict(default='present', choices=['present', 'absent']),
+            backup=dict(default=False, type='bool'),
+        ),
+        mutually_exclusive=[['insertbefore', 'insertafter']],
+        supports_check_mode=False,
+    )
+
+    name = module.params['name']
+    value = module.params['value']
+    user = module.params['user']
+    cron_file = module.params['cron_file']
+    insertafter = module.params['insertafter']
+    insertbefore = module.params['insertbefore']
+    state = module.params['state']
+    backup = module.params['backup']
+    ensure_present = state == 'present'
+
+    changed = False
+    res_args = dict()
+
+    # Ensure all files generated are only writable by the owning user.  Primarily relevant for the cron_file option.
+    os.umask(022)
+    cronvar = CronVar(module, user, cron_file)
+
+    if cronvar.syslogging:
+        syslog.openlog('ansible-%s' % os.path.basename(__file__))
+        syslog.syslog(syslog.LOG_NOTICE, 'cronvar instantiated - name: "%s"' % name)
+
+    # --- user input validation ---
+
+    if name is None and ensure_present:
+        module.fail_json(msg="You must specify 'name' to insert a new cron variabale")
+
+    if value is None and ensure_present:
+        module.fail_json(msg="You must specify 'value' to insert a new cron variable")
+
+    if name is None and not ensure_present:
+        module.fail_json(msg="You must specify 'name' to remove a cron variable")
+
+    # if requested make a backup before making a change
+    if backup:
+        (_, backup_file) = tempfile.mkstemp(prefix='cronvar')
+        cronvar.write(backup_file)
+
+    if cronvar.cron_file and not name and not ensure_present:
+        changed = cronvar.remove_job_file()
+        module.exit_json(changed=changed, cron_file=cron_file, state=state)
+
+    old_value = cronvar.find_variable(name)
+
+    if ensure_present:
+        if old_value is None:
+            cronvar.add_variable(name, value, insertbefore, insertafter)
+            changed = True
+        elif old_value != value:
+            cronvar.update_variable(name, value)
+            changed = True
+    else:
+        if old_value is not None:
+            cronvar.remove_variable(name)
+            changed = True
+
+    res_args = {
+        "vars": cronvar.get_var_names(),
+        "changed": changed
+    }
+
+    if changed:
+        cronvar.write()
+
+    # retain the backup only if crontab or cron file have changed
+    if backup:
+        if changed:
+            res_args['backup_file'] = backup_file
+        else:
+            os.unlink(backup_file)
+
+    if cron_file:
+        res_args['cron_file'] = cron_file
+
+    module.exit_json(**res_args)
+
+    # --- should never get here
+    module.exit_json(msg="Unable to execute cronvar task.")
+
+# import module snippets
+from ansible.module_utils.basic import *
+
+main()