ansible/library/service

#!/usr/bin/python

# (c) 2012, Michael DeHaan <michael.dehaan@gmail.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/>.

try:
    import json
except ImportError:
    import simplejson as json
import sys
import shlex
import subprocess
import os.path
import syslog

# TODO: switch to fail_json and other helper functions
# like other modules are using

# ===========================================

SERVICE = None
CHKCONFIG = None

def fail_json(d):
    print json.dumps(d)
    sys.exit(1)

def _find_binaries():
    # list of possible paths for service/chkconfig binaries
    # with the most probable first
    global CHKCONFIG
    global SERVICE
    global INITCTL
    paths = ['/sbin', '/usr/sbin', '/bin', '/usr/bin']
    binaries = [ 'service', 'chkconfig', 'update-rc.d', 'initctl']
    location = dict()

    for binary in binaries:
        location[binary] = None

    for binary in binaries:
        for path in paths:
            if os.path.exists(path + '/' + binary):
                location[binary] = path + '/' + binary
                break

    if location.get('chkconfig', None):
        CHKCONFIG = location['chkconfig']
    elif location.get('update-rc.d', None):
        CHKCONFIG = location['update-rc.d']
    else:
        fail_json(dict(failed=True, msg='unable to find chkconfig or update-rc.d binary'))
    if location.get('service', None):
        SERVICE = location['service']
    else:
        fail_json(dict(failed=True, msg='unable to find service binary'))
    if location.get('initctl', None):
        INITCTL = location['initctl']
    else:
        INITCTL = None

def _get_service_status(name):
    rc, status_stdout, status_stderr = _run("%s %s status" % (SERVICE, name))
    status = status_stdout + status_stderr

    # set the running state to None because we don't know it yet
    running = None

    # Check if we got upstart on the system and then the job state
    if INITCTL != None:
        # check the job status by upstart response
        initctl_rc, initctl_status_stdout, initctl_status_stderr = _run("%s status %s" % (INITCTL, name))
        if initctl_status_stdout.find("stop/waiting") != -1:
            running = False
        elif initctl_status_stdout.find("start/running") != -1:
            running = True

    # if the job status is still not known check it by response code
    if running == None:
        if rc == 3:
            running = False
        elif rc == 0:
            running = True

    # if the job status is still not known check it by status output keywords
    if running == None:
        # first tranform the status output that could irritate keyword matching
        cleaned_status_stdout = status_stdout.lower().replace(name.lower(),'')
        if cleaned_status_stdout.find("stop") != -1:
            running = False
        elif cleaned_status_stdout.find("run") != -1 and cleaned_status_stdout.find("not") != -1:
            running = False
        elif cleaned_status_stdout.find("run") != -1 and cleaned_status_stdout.find("not") == -1:
            running = True
        elif cleaned_status_stdout.find("start") != -1 and cleaned_status_stdout.find("not") == -1:
            running = True
        elif 'could not access pid file' in cleaned_status_stdout:
            running = False

    # if the job status is still not known check it by special conditions
    if running == None:
        if name == 'iptables' and status_stdout.find("ACCEPT") != -1:
            # iptables status command output is lame
            # TODO: lookup if we can use a return code for this instead?
            running = True
    
    return running

def _run(cmd):
    # returns (rc, stdout, stderr) from shell command
    process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
    stdout, stderr = process.communicate()
    return (process.returncode, stdout, stderr) 


def _do_enable(name, enable):
    # we change argument depending on real binary used
    # update-rc.d wants enable/disable while
    # chkconfig wants on/off
    valid_argument = dict({'on' : 'on', 'off' : 'off'})

    if CHKCONFIG.endswith("update-rc.d"):
        valid_argument['on'] = "enable"
        valid_argument['off'] = "disable"

    if enable.lower() in ['on', 'true', 'yes', 'enable']:
        rc, stdout, stderr = _run("%s %s %s" % (CHKCONFIG, name, valid_argument['on']))
    elif enable.lower() in ['off', 'false', 'no', 'disable']:
        rc, stdout, stderr = _run("%s %s %s" % (CHKCONFIG, name, valid_argument['off']))
    
    return rc, stdout, stderr
    
argfile = sys.argv[1]
args = open(argfile, 'r').read()
items = shlex.split(args)
syslog.openlog('ansible-%s' % os.path.basename(__file__))
syslog.syslog(syslog.LOG_NOTICE, 'Invoked with %s' % args)

if not len(items):
    fail_json(dict(failed=True, msg='this module requires arguments (-a)'))

params = {}
for arg in items:
    if "=" not in arg:
        fail_json(dict(failed=True, msg='expected key=value format arguments'))

    (name, value) = arg.split("=")
    params[name] = value

name = params.get('name', None)

if name is None:
    fail_json(dict(failed=True, msg='missing name'))

state = params.get('state', None)
list_items = params.get('list', None)
enable = params.get('enabled', params.get('enable', None))

# running and started are the same
if state and state.lower() not in [ 'running', 'started', 'stopped', 'restarted','reloaded' ]:
    fail_json(dict(failed=True, msg='invalid value for state'))
if list_items and list_items.lower() not in [ 'status' ]:
    fail_json(dict(failed=True, msg='invalid value for list'))
if enable and enable.lower() not in [ 'on', 'off', 'true', 'false', 'yes', 'no', 'enable', 'disable' ]:
    fail_json(dict(failed=True, msg='invalid value for enable'))
    

# ===========================================
# find binaries locations on minion
_find_binaries()


# ===========================================
# get service status
running = _get_service_status(name)


if state or enable:
    rc = 0
    out = ''
    err = ''
    changed = False
        
    if enable:
        rc_enable, out_enable, err_enable = _do_enable(name, enable)
        rc += rc_enable
        out += out_enable
        err += err_enable

    if state and running == None:
        print json.dumps({
            "failed" : True,
            "msg"    : "failed determining the current service state => state stays unchanged",
        })
        print >> sys.stderr, out + err
    elif state:
        # a state change command has been requested

        # ===========================================
        # determine if we are going to change anything

        if not running and state in ("started", "running"):
            changed = True
        elif running and state in ("stopped","reloaded"):
            changed = True
        elif state == "restarted":
            changed = True

        # ===========================================
        # run change commands if we need to

        if changed:
            if state in ('started', 'running'):
                rc_state, stdout, stderr = _run("%s %s start" % (SERVICE, name))
            elif state == 'stopped':
                rc_state, stdout, stderr = _run("%s %s stop" % (SERVICE, name))
            elif state == 'reloaded':
                rc_state, stdout, stderr = _run("%s %s reload" % (SERVICE, name))
            elif state == 'restarted':
                rc1, stdout1, stderr1 = _run("%s %s stop" % (SERVICE, name))
                rc2, stdout2, stderr2 = _run("%s %s start" % (SERVICE, name))
                rc_state = rc + rc1 + rc2
                stdout = stdout1 + stdout2
                stderr = stderr1 + stderr2

            out += stdout
            err += stderr
            rc = rc + rc_state

    if rc != 0:

        print json.dumps({
            "failed" : 1,
            "rc"     : rc,
        })
        print >> sys.stderr, out + err
        sys.exit(1)


    # ===============================================
    # success

    result = {"changed": changed}

    rc, stdout, stderr = _run("%s %s status" % (SERVICE, name))
    if list_items and list_items in [ 'status' ]:
        result['status'] = stdout
    print json.dumps(result)

    
elif list_items is not None:

    # solo list=status mode, don't change anything, just return
    # suitable for /usr/bin/ansible usage or API, playbooks
    # not so much

    print json.dumps({
        "status" : status
    })

else:
 
    print json.dumps(dict(failed=True, msg="expected state or list parameters"))


sys.exit(0)