ansible/library/service

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

# (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/>.

DOCUMENTATION = '''
---
module: service
author: Michael DeHaan
version_added: 0.1
short_description:  Manage services.
description:
    - Controls services on remote hosts.
options:
    name:
        required: true
        description:
        - Name of the service.
    state:
        required: false
        choices: [ started, stopped, restarted, reloaded ]
        description:
          - C(started)/C(stopped) are idempotent actions that will not run
            commands unless necessary.  C(restarted) will always bounce the
            service.  C(reloaded) will always reload.
    pattern:
        required: false
        version_added: "0.7"
        description:
        - If the service does not respond to the status command, name a
          substring to look for as would be found in the output of the I(ps)
          command as a stand-in for a status result.  If the string is found,
          the service will be assumed to be running.
    enabled:
        required: false
        choices: [ "yes", "no" ]
        description:
        - Whether the service should start on boot.
    arguments:
        description:
        - Additional arguments provided on the command line
        aliases: [ 'args' ]
examples:
    - description: Example action to start service httpd, if not running
      code: "service: name=httpd state=started"
    - description: Example action to stop service httpd, if running
      code: "service: name=httpd state=stopped"
    - description: Example action to restart service httpd, in all cases
      code: "service: name=httpd state=restarted"
    - description: Example action to reload service httpd, in all cases
      code: "service: name=httpd state=reloaded"
    - description: Example action to start service foo, based on running process /usr/bin/foo
      code: "service: name=foo pattern=/usr/bin/foo state=started"
    - description: Example action to restart network service for interface eth0
      code: "service: name=network state=restarted args=eth0"
'''

import platform
import os
import tempfile
import shlex
import select

class Service(object):
    """
    This is the generic Service manipulation class that is subclassed
    based on platform.

    A subclass should override the following action methods:-
      - get_service_tools
      - service_enable
      - get_service_status
      - service_control

    All subclasses MUST define platform and distribution (which may be None).
    """

    platform = 'Generic'
    distribution = None

    def __new__(cls, *args, **kwargs):
        return load_platform_subclass(Service, args, kwargs)

    def __init__(self, module):
        self.module         = module
        self.name           = module.params['name']
        self.state          = module.params['state']
        self.pattern        = module.params['pattern']
        self.enable         = module.boolean(module.params.get('enabled', None))
        self.changed        = False
        self.running        = None
        self.action         = None
        self.svc_cmd        = None
        self.svc_initscript = None
        self.svc_initctl    = None
        self.enable_cmd     = None
        self.arguments      = module.params.get('arguments', '')
        self.rcconf_file    = None
        self.rcconf_key     = None
        self.rcconf_value   = None

        # select whether we dump additional debug info through syslog
        self.syslogging = False

# ===========================================
# Platform specific methods (must be replaced by subclass).

    def get_service_tools(self):
        self.module.fail_json(msg="get_service_tools not implemented on target platform")

    def service_enable(self):
        self.module.fail_json(msg="service_enable not implemented on target platform")

    def get_service_status(self):
        self.module.fail_json(msg="get_service_status not implemented on target platform")

    def service_control(self):
        self.module.fail_json(msg="service_control not implemented on target platform")

# ===========================================
# Generic methods that should be used on all platforms.

    def execute_command(self, cmd, daemonize=False):
        if self.syslogging:
            syslog.openlog('ansible-%s' % os.path.basename(__file__))
            syslog.syslog(syslog.LOG_NOTICE, 'Command %s, daemonize %r' % (cmd, daemonize))

        # Most things don't need to be daemonized
        if not daemonize:
            return self.module.run_command(cmd)

        # This is complex because daemonization is hard for people.
        # What we do is daemonize a part of this module, the daemon runs the
        # command, picks up the return code and output, and returns it to the
        # main process.
        pipe = os.pipe()
        pid = os.fork()
        if pid == 0:
            os.close(pipe[0])
            # Set stdin/stdout/stderr to /dev/null
            fd = os.open(os.devnull, os.O_RDWR)
            if fd != 0:
                os.dup2(fd, 0)
            if fd != 1:
                os.dup2(fd, 1)
            if fd != 2:
                os.dup2(fd, 2)
            if fd not in (0, 1, 2):
                os.close(fd)

            # Make us a daemon. Yes, that's all it takes.
            pid = os.fork()
            if pid > 0:
                os._exit(0)
            os.setsid()
            os.chdir("/")
            pid = os.fork()
            if pid > 0:
                os._exit(0)

            # Start the command
            p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, preexec_fn=lambda: os.close(pipe[1]))
            stdout = ""
            stderr = ""
            fds = [p.stdout, p.stderr]
            # Wait for all output, or until the main process is dead and its output is done.
            while fds:
                rfd, wfd, efd = select.select(fds, [], fds, 1)
                if not (rfd + wfd + efd) and p.poll() is not None:
                    break
                if p.stdout in rfd:
                    dat = os.read(p.stdout.fileno(), 4096)
                    if not dat:
                        fds.remove(p.stdout)
                    stdout += dat
                if p.stderr in rfd:
                    dat = os.read(p.stderr.fileno(), 4096)
                    if not dat:
                        fds.remove(p.stderr)
                    stderr += dat
            p.wait()
            # Return a JSON blob to parent
            os.write(pipe[1], json.dumps([p.returncode, stdout, stderr]))
            os.close(pipe[1])
            os._exit(0)
        elif pid == -1:
            self.module.fail_json(msg="unable to fork")
        else:
            os.close(pipe[1])
            os.waitpid(pid, 0)
            # Wait for data from daemon process and process it.
            data = ""
            while True:
                rfd, wfd, efd = select.select([pipe[0]], [], [pipe[0]])
                if pipe[0] in rfd:
                    dat = os.read(pipe[0], 4096)
                    if not dat:
                        break
                    data += dat
            return json.loads(data)

    def check_ps(self):
        # Set ps flags
        if platform.system() == 'SunOS':
            psflags = '-ef'
        else:
            psflags = 'auxww'

        # Find ps binary
        psbin = self.module.get_bin_path('ps', True)

        (rc, psout, pserr) = self.execute_command('%s %s' % (psbin, psflags))
        # If rc is 0, set running as appropriate
        if rc == 0:
            self.running = False
            lines = psout.split("\n")
            for line in lines:
                if self.pattern in line and not "pattern=" in line:
                    # so as to not confuse ./hacking/test-module
                    self.running = True
                    break

    def check_service_changed(self):
        if self.state and self.running == None:
            self.module.fail_json(msg="failed determining the current service state => state stays unchanged")
        # Find out if state has changed
        if not self.running and self.state in ["started", "running"]:
            self.changed = True
        elif self.running and self.state in ["stopped","reloaded"]:
            self.changed = True
        elif self.state == "restarted":
            self.changed = True

    def modify_service_state(self):
        # Only do something if state will change
        if self.changed:
            # Control service
            if self.state in ['started', 'running']:
                self.action = "start"
            elif self.state == 'stopped':
                self.action = "stop"
            elif self.state == 'reloaded':
                self.action = "reload"
            elif self.state == 'restarted':
                self.action = "restart"

            return self.service_control()

        else:
            # If nothing needs to change just say all is well
            rc = 0
            err = ''
            out = ''
            return rc, out, err

    def service_enable_rcconf(self):
        if self.rcconf_file is None or self.rcconf_key is None or self.rcconf_value is None:
            self.module.fail_json(msg="service_enable_rcconf() requires rcconf_file, rcconf_key and rcconf_value")

        changed = None
        entry = '%s="%s"\n' % (self.rcconf_key, self.rcconf_value)
        RCFILE = open(self.rcconf_file, "r")
        new_rc_conf = []

        # Build a list containing the possibly modified file. 
        for rcline in RCFILE:
            # Parse line removing whitespaces, quotes, etc.
            rcarray = shlex.split(rcline, comments=True)
            if len(rcarray) >= 1 and '=' in rcarray[0]:
                (key, value) = rcarray[0].split("=", 1)
                if key == self.rcconf_key:
                    if value == self.rcconf_value:
                        # Since the proper entry already exists we can stop iterating.
                        changed = False
                        break
                    else: 
                        # We found the key but the value is wrong, replace with new entry.
                        rcline = entry
                        changed = True

            # Add line to the list.
            new_rc_conf.append(rcline)

        # We are done with reading the current rc.conf, close it.
        RCFILE.close()

        # If we did not see any trace of our entry we need to add it.
        if changed is None:
            new_rc_conf.append(entry)
            changed = True

        if changed is True:
            # Create a temporary file next to the current rc.conf (so we stay on the same filesystem).
            # This way the replacement operation is atomic.
            rcconf_dir = os.path.dirname(self.rcconf_file)
            rcconf_base = os.path.basename(self.rcconf_file)
            (TMP_RCCONF, tmp_rcconf_file) = tempfile.mkstemp(dir=rcconf_dir, prefix="%s-" % rcconf_base)

            # Write out the contents of the list into our temporary file.
            for rcline in new_rc_conf:
                os.write(TMP_RCCONF, rcline)

            # Close temporary file.
            os.close(TMP_RCCONF)

            # Replace previous rc.conf.
            self.module.atomic_replace(tmp_rcconf_file, self.rcconf_file)

# ===========================================
# Subclass: Linux

class LinuxService(Service):
    """
    This is the Linux Service manipulation class - it is currently supporting
    a mixture of binaries and init scripts for controlling services started at
    boot, as well as for controlling the current state.
    """

    platform = 'Linux'
    distribution = None

    def get_service_tools(self):
        paths = [ '/sbin', '/usr/sbin', '/bin', '/usr/bin' ]
        binaries = [ 'service', 'chkconfig', 'update-rc.d', 'initctl', 'systemctl' ]
        initpaths = [ '/etc/init.d' ]
        location = dict()

        for binary in binaries:
            location[binary] = None

        for binary in binaries:
            location[binary] = self.module.get_bin_path(binary)

        # Locate a tool for enable options
        if location.get('systemctl', None):
            self.enable_cmd = location['systemctl']
        elif location.get('chkconfig', None):
            self.enable_cmd = location['chkconfig']
        elif location.get('update-rc.d', None):
            self.enable_cmd = location['update-rc.d']

        if self.enable_cmd is None:
            self.module.fail_json(msg='unable to find enable binary')

        # Locate a tool for runtime service management (start, stop etc.)
        if location.get('service', None):
            self.svc_cmd = location['service']
        else:
            for initdir in initpaths:
                initscript = "%s/%s" % (initdir,self.name)
                if os.path.isfile(initscript):
                    self.svc_initscript = initscript

        if not self.svc_cmd and not self.svc_initscript:
            self.module.fail_json(msg='unable to find service binary nor initscript')

        if location.get('initctl', None):
            self.svc_initctl = location['initctl']

    def get_service_status(self):
        self.action = "status"
        rc, status_stdout, status_stderr = self.service_control()

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

        # if the job status is still not known check it by response code
        if self.running == None:
            if rc in [2, 3, 4, 69]:
                self.running = False
            elif rc == 0:
                self.running = True

        # if the job status is still not known check it by status output keywords
        if self.running == None:
            # first tranform the status output that could irritate keyword matching
            cleanout = status_stdout.lower().replace(self.name.lower(), '')
            if "stop" in cleanout:
                self.running = False
            elif "run" in cleanout and "not" in cleanout:
                self.running = False
            elif "run" in cleanout and "not" not in cleanout:
                self.running = True
            elif "start" in cleanout and "not" not in cleanout:
                self.running = True
            elif 'could not access pid file' in cleanout:
                self.running = False
            elif 'is dead and pid file exists' in cleanout:
                self.running = False
            elif 'dead but subsys locked' in cleanout:
                self.running = False
            elif 'dead but pid file exists' in cleanout:
                self.running = False

        # if the job status is still not known check it by special conditions
        if self.running == None:
            if self.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?
                self.running = True

    def service_enable(self):
        # we change argument depending on real binary used
        # update-rc.d wants enable/disable while
        # chkconfig wants on/off
        # also, systemctl needs the arguments reversed
        if self.enable:
            on_off = "on"
            enable_disable = "enable"
        else:
            on_off = "off"
            enable_disable = "disable"

        if self.enable_cmd.endswith("update-rc.d"):
            args = (self.enable_cmd, self.name, enable_disable)
        elif self.enable_cmd.endswith("systemctl"):
            args = (self.enable_cmd, enable_disable, self.name + ".service")
        else:
            args = (self.enable_cmd, self.name, on_off)

        if self.enable is not None:
            return self.execute_command("%s %s %s" % args)

    def service_control(self):

        # Decide what command to run
        if self.svc_cmd:
            svc_cmd = "%s %s" % (self.svc_cmd, self.name)
        elif self.svc_initscript:
            svc_cmd = "%s" % self.svc_initscript

        if self.action is not "restart":
            rc_state, stdout, stderr = self.execute_command("%s %s %s" % (svc_cmd, self.action, self.arguments), daemonize=True)
        else:
            rc1, stdout1, stderr1 = self.execute_command("%s %s %s" % (svc_cmd, 'stop', self.arguments), daemonize=True)
            rc2, stdout2, stderr2 = self.execute_command("%s %s %s" % (svc_cmd, 'start', self.arguments), daemonize=True)
            if rc1 != 0 and rc2 == 0:
                rc_state = rc2
                stdout = stdout2
                stderr = stderr2
            else:
                rc_state = rc1 + rc2
                stdout = stdout1 + stdout2
                stderr = stderr1 + stderr2

        return(rc_state, stdout, stderr)

# ===========================================
# Subclass: FreeBSD

class FreeBsdService(Service):
    """
    This is the FreeBSD Service manipulation class - it uses the /etc/rc.conf
    file for controlling services started at boot and the 'service' binary to
    check status and perform direct service manipulation.
    """

    platform = 'FreeBSD'
    distribution = None

    def get_service_tools(self):
        self.svc_cmd = self.module.get_bin_path('service', True)

        if not self.svc_cmd:
            self.module.fail_json(msg='unable to find service binary')

    def get_service_status(self):
        rc, stdout, stderr = self.execute_command("%s %s %s" % (self.svc_cmd, self.name, 'onestatus'))
        if rc == 1:
            self.running = False
        elif rc == 0:
            self.running = True

    def service_enable(self):
        if self.enable:
            self.rcconf_value = "YES"
        else:
            self.rcconf_value = "NO"

        rcfiles = [ '/etc/rc.conf','/usr/local/etc/rc.conf' ]
        for rcfile in rcfiles:
            if os.path.isfile(rcfile):
                self.rcconf_file = rcfile
        
        self.rcconf_key = "%s_enable" % self.name

        return self.service_enable_rcconf()

    def service_control(self):
        if self.action is "start":
            self.action = "onestart"
        if self.action is "stop":
            self.action = "onestop"
        if self.action is "reload":
            self.action = "onereload"

        return self.execute_command("%s %s %s" % (self.svc_cmd, self.name, self.action))

# ===========================================
# Subclass: OpenBSD

class OpenBsdService(Service):
    """
    This is the OpenBSD Service manipulation class - it uses /etc/rc.d for
    service control. Enabling a service is currently not supported because the
    <service>_flags variable is not boolean, you should supply a rc.conf.local
    file in some other way.
    """

    platform = 'OpenBSD'
    distribution = None

    def get_service_tools(self):
        rcdir = '/etc/rc.d'

        rc_script = "%s/%s" % (rcdir, self.name)
        if os.path.isfile(rc_script):
            self.svc_cmd = rc_script

        if not self.svc_cmd:
            self.module.fail_json(msg='unable to find rc.d script')

    def get_service_status(self):
        rc, stdout, stderr = self.execute_command("%s %s" % (self.svc_cmd, 'check'))
        if rc == 1:
            self.running = False
        elif rc == 0:
            self.running = True

    def service_control(self):
        return self.execute_command("%s %s" % (self.svc_cmd, self.action))

# ===========================================
# Main control flow

def main():
    module = AnsibleModule(
        argument_spec = dict(
            name = dict(required=True),
            state = dict(choices=['running', 'started', 'stopped', 'restarted', 'reloaded']),
            pattern = dict(required=False, default=None),
            enabled = dict(choices=BOOLEANS),
            arguments = dict(aliases=['args'], default=''),
        )
    )

    service = Service(module)

    if service.syslogging:
        syslog.openlog('ansible-%s' % os.path.basename(__file__))
        syslog.syslog(syslog.LOG_NOTICE, 'Service instantiated - platform %s' % service.platform)
        if service.distribution:
            syslog.syslog(syslog.LOG_NOTICE, 'Service instantiated - distribution %s' % service.distribution)

    rc = 0
    out = ''
    err = ''
    result = {}
    result['name'] = service.name
    result['state'] = service.state

    # Find service management tools
    service.get_service_tools()

    # Enable/disable service startup at boot if requested
    if service.module.params['enabled']:
        service.service_enable()

    # Collect service status
    if service.pattern:
        service.check_ps()
    service.get_service_status()

    # Calculate if request will change service state
    service.check_service_changed()

    # Modify service state if necessary
    (rc, out, err) = service.modify_service_state()

    if rc != 0:
        if err:
            module.fail_json(msg=err)
        else:
            module.fail_json(msg=out)

    result['changed'] = service.changed
    if service.module.params['enabled']:
        result['enabled'] = service.module.params['enabled']
    if service.state:
        result['state'] = service.state

    module.exit_json(**result)

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

main()