ceph/src/pybind/mgr/hello/module.py

   1
   2 """
   3 A hello world module
   4
   5 See doc/mgr/hello.rst for more info.
   6 """
   7
   8 from mgr_module import CLIReadCommand, HandleCommandResult, MgrModule, Option
   9 from threading import Event
  10 from typing import cast, Any, Optional, TYPE_CHECKING
  11 import errno
  12
  13
  14 class Hello(MgrModule):
  15     # These are module options we understand.  These can be set with
  16     #
  17     #   ceph config set global mgr/hello/<name> <value>
  18     #
  19     # e.g.,
  20     #
  21     #   ceph config set global mgr/hello/place Earth
  22     #
  23     MODULE_OPTIONS = [
  24         Option(name='place',
  25                default='world',
  26                desc='a place in the world',
  27                runtime=True),   # can be updated at runtime (no mgr restart)
  28         Option(name='emphatic',
  29                type='bool',
  30                desc='whether to say it loudly',
  31                default=True,
  32                runtime=True),
  33         Option(name='foo',
  34                type='str',
  35                enum_allowed=['a', 'b', 'c'],
  36                default='a',
  37                runtime=True)
  38     ]
  39
  40     # These are "native" Ceph options that this module cares about.
  41     NATIVE_OPTIONS = [
  42         'mgr_tick_period',
  43     ]
  44
  45     def __init__(self, *args: Any, **kwargs: Any):
  46         super().__init__(*args, **kwargs)
  47
  48         # set up some members to enable the serve() method and shutdown()
  49         self.run = True
  50         self.event = Event()
  51
  52         # ensure config options members are initialized; see config_notify()
  53         self.config_notify()
  54
  55         # for mypy which does not run the code
  56         if TYPE_CHECKING:
  57             self.mgr_tick_period = 0
  58
  59     def config_notify(self) -> None:
  60         """
  61         This method is called whenever one of our config options is changed.
  62         """
  63         # This is some boilerplate that stores MODULE_OPTIONS in a class
  64         # member, so that, for instance, the 'emphatic' option is always
  65         # available as 'self.emphatic'.
  66         for opt in self.MODULE_OPTIONS:
  67             setattr(self,
  68                     opt['name'],
  69                     self.get_module_option(opt['name']))
  70             self.log.debug(' mgr option %s = %s',
  71                            opt['name'], getattr(self, opt['name']))
  72         # Do the same for the native options.
  73         for opt in self.NATIVE_OPTIONS:
  74             setattr(self,
  75                     opt,
  76                     self.get_ceph_option(opt))
  77             self.log.debug(' native option %s = %s', opt, getattr(self, opt))
  78
  79     # there are CLI commands we implement
  80     @CLIReadCommand('hello')
  81     def hello(self, person_name: Optional[str] = None) -> HandleCommandResult:
  82         """
  83         Say hello
  84         """
  85         if person_name is None:
  86             who = cast(str, self.get_module_option('place'))
  87         else:
  88             who = person_name
  89         fin = '!' if self.get_module_option('emphatic') else ''
  90         return HandleCommandResult(stdout=f'Hello, {who}{fin}')
  91
  92     @CLIReadCommand('count')
  93     def count(self, num: int) -> HandleCommandResult:
  94         """
  95         Do some counting
  96         """
  97         ret = 0
  98         out = ''
  99         err = ''
 100         if num < 1:
 101             err = 'That\'s too small a number'
 102             ret = -errno.EINVAL
 103         elif num > 10:
 104             err = 'That\'s too big a number'
 105             ret = -errno.EINVAL
 106         else:
 107             out = 'Hello, I am the count!\n'
 108             out += ', '.join([str(x) for x in range(1, num + 1)]) + '!'
 109         return HandleCommandResult(retval=ret,
 110                                    stdout=out,
 111                                    stderr=err)
 112
 113     def serve(self) -> None:
 114         """
 115         This method is called by the mgr when the module starts and can be
 116         used for any background activity.
 117         """
 118         self.log.info("Starting")
 119         while self.run:
 120             # Do some useful background work here.
 121
 122             # Use mgr_tick_period (default: 2) here just to illustrate
 123             # consuming native ceph options.  Any real background work
 124             # would presumably have some more appropriate frequency.
 125             sleep_interval = self.mgr_tick_period
 126             self.log.debug('Sleeping for %d seconds', sleep_interval)
 127             self.event.wait(sleep_interval)
 128             self.event.clear()
 129
 130     def shutdown(self) -> None:
 131         """
 132         This method is called by the mgr when the module needs to shut
 133         down (i.e., when the serve() function needs to exit).
 134         """
 135         self.log.info('Stopping')
 136         self.run = False
 137         self.event.set()