1 files changed, 137 insertions, 0 deletions
diff --git a/src/pybind/mgr/hello/module.py b/src/pybind/mgr/hello/module.py
new file mode 100644
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+++ b/src/pybind/mgr/hello/module.py
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+
+"""
+A hello world module
+
+See doc/mgr/hello.rst for more info.
+"""
+
+from mgr_module import CLIReadCommand, HandleCommandResult, MgrModule, Option
+from threading import Event
+from typing import cast, Any, Optional, TYPE_CHECKING
+import errno
+
+
+class Hello(MgrModule):
+    # These are module options we understand.  These can be set with
+    #
+    #   ceph config set global mgr/hello/<name> <value>
+    #
+    # e.g.,
+    #
+    #   ceph config set global mgr/hello/place Earth
+    #
+    MODULE_OPTIONS = [
+        Option(name='place',
+               default='world',
+               desc='a place in the world',
+               runtime=True),   # can be updated at runtime (no mgr restart)
+        Option(name='emphatic',
+               type='bool',
+               desc='whether to say it loudly',
+               default=True,
+               runtime=True),
+        Option(name='foo',
+               type='str',
+               enum_allowed=['a', 'b', 'c'],
+               default='a',
+               runtime=True)
+    ]
+
+    # These are "native" Ceph options that this module cares about.
+    NATIVE_OPTIONS = [
+        'mgr_tick_period',
+    ]
+
+    def __init__(self, *args: Any, **kwargs: Any):
+        super().__init__(*args, **kwargs)
+
+        # set up some members to enable the serve() method and shutdown()
+        self.run = True
+        self.event = Event()
+
+        # ensure config options members are initialized; see config_notify()
+        self.config_notify()
+
+        # for mypy which does not run the code
+        if TYPE_CHECKING:
+            self.mgr_tick_period = 0
+
+    def config_notify(self) -> None:
+        """
+        This method is called whenever one of our config options is changed.
+        """
+        # This is some boilerplate that stores MODULE_OPTIONS in a class
+        # member, so that, for instance, the 'emphatic' option is always
+        # available as 'self.emphatic'.
+        for opt in self.MODULE_OPTIONS:
+            setattr(self,
+                    opt['name'],
+                    self.get_module_option(opt['name']))
+            self.log.debug(' mgr option %s = %s',
+                           opt['name'], getattr(self, opt['name']))
+        # Do the same for the native options.
+        for opt in self.NATIVE_OPTIONS:
+            setattr(self,
+                    opt,
+                    self.get_ceph_option(opt))
+            self.log.debug(' native option %s = %s', opt, getattr(self, opt))
+
+    # there are CLI commands we implement
+    @CLIReadCommand('hello')
+    def hello(self, person_name: Optional[str] = None) -> HandleCommandResult:
+        """
+        Say hello
+        """
+        if person_name is None:
+            who = cast(str, self.get_module_option('place'))
+        else:
+            who = person_name
+        fin = '!' if self.get_module_option('emphatic') else ''
+        return HandleCommandResult(stdout=f'Hello, {who}{fin}')
+
+    @CLIReadCommand('count')
+    def count(self, num: int) -> HandleCommandResult:
+        """
+        Do some counting
+        """
+        ret = 0
+        out = ''
+        err = ''
+        if num < 1:
+            err = 'That\'s too small a number'
+            ret = -errno.EINVAL
+        elif num > 10:
+            err = 'That\'s too big a number'
+            ret = -errno.EINVAL
+        else:
+            out = 'Hello, I am the count!\n'
+            out += ', '.join([str(x) for x in range(1, num + 1)]) + '!'
+        return HandleCommandResult(retval=ret,
+                                   stdout=out,
+                                   stderr=err)
+
+    def serve(self) -> None:
+        """
+        This method is called by the mgr when the module starts and can be
+        used for any background activity.
+        """
+        self.log.info("Starting")
+        while self.run:
+            # Do some useful background work here.
+
+            # Use mgr_tick_period (default: 2) here just to illustrate
+            # consuming native ceph options.  Any real background work
+            # would presumably have some more appropriate frequency.
+            sleep_interval = self.mgr_tick_period
+            self.log.debug('Sleeping for %d seconds', sleep_interval)
+            self.event.wait(sleep_interval)
+            self.event.clear()
+
+    def shutdown(self) -> None:
+        """
+        This method is called by the mgr when the module needs to shut
+        down (i.e., when the serve() function needs to exit).
+        """
+        self.log.info('Stopping')
+        self.run = False
+        self.event.set()