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/>.

SERVICE = None
CHKCONFIG = None
INITCTL = None

def _find_binaries(m):
    # list of possible paths for service/chkconfig binaries
    # with the most probable first
    global SERVICE
    global CHKCONFIG
    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:
        m.fail_json(msg='unable to find chkconfig or update-rc.d binary')
    if location.get('service', None):
        SERVICE = location['service']
    else:
        m.fail_json(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))

    # 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
        cleanout = status_stdout.lower().replace(name.lower(), '')
        if "stop" in cleanout:
            running = False
        elif "run" in cleanout and "not" in cleanout:
            running = False
        elif "run" in cleanout and "not" not in cleanout:
            running = True
        elif "start" in cleanout and "not" not in cleanout:
            running = True
        elif 'could not access pid file' in cleanout:
            running = False
        elif 'is dead and pid file exists' in cleanout:
            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 is not None:
        if enable:
            rc, stdout, stderr = _run("%s %s %s" % (CHKCONFIG, name, valid_argument['on']))
        else:
            rc, stdout, stderr = _run("%s %s %s" % (CHKCONFIG, name, valid_argument['off']))
    
    return rc, stdout, stderr
    
def main():
    module = AnsibleModule(
        argument_spec = dict(
            name = dict(required=True),
            state = dict(required=True, choices=['running', 'started', 'stopped', 'restarted', 'reloaded']),
            enable = dict(choices=BOOLEANS)
        )
    )

    name = module.params['name']
    state = module.params['state']
    enable = module.boolean(module.params.get('enable', None))

    # ===========================================
    # find binaries locations on minion
    _find_binaries(module)
    
    # ===========================================
    # get service status
    running = _get_service_status(name)

    # ===========================================
    # Some common variables
    changed = False
    rc = 0
    err = ''
    out = ''
    
    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:
        module.fail_json(msg="failed determining the current service state => state stays unchanged", changed=False)

    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:
        module.fail_json(msg=err)

    result = {"changed": changed}
    rc, stdout, stderr = _run("%s %s status" % (SERVICE, name))
    module.exit_json(**result);
    

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

main()