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# Copyright 2015, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""Reference implementation for health checking in gRPC Python."""
import abc
import enum
import threading
from grpc.health.v1 import health_pb2
@enum.unique
class HealthStatus(enum.Enum):
"""Statuses for a service mirroring the reference health.proto's values."""
UNKNOWN = health_pb2.HealthCheckResponse.UNKNOWN
SERVING = health_pb2.HealthCheckResponse.SERVING
NOT_SERVING = health_pb2.HealthCheckResponse.NOT_SERVING
class _HealthServicer(health_pb2.EarlyAdopterHealthServicer):
"""Servicer handling RPCs for service statuses."""
def __init__(self):
self._server_status_lock = threading.Lock()
self._server_status = {}
def Check(self, request, context):
with self._server_status_lock:
if request.service not in self._server_status:
# TODO(atash): once the Python API has a way of setting the server
# status, bring us into conformance with the health check spec by
# returning the NOT_FOUND status here.
raise NotImplementedError()
else:
return health_pb2.HealthCheckResponse(
status=self._server_status[request.service].value)
def set(service, status):
if not isinstance(status, HealthStatus):
raise TypeError('expected grpc.health.v1.health.HealthStatus '
'for argument `status` but got {}'.format(status))
with self._server_status_lock:
self._server_status[service] = status
class HealthServer(health_pb2.EarlyAdopterHealthServer):
"""Interface for the reference gRPC Python health server."""
__metaclass__ = abc.ABCMeta
@abc.abstractmethod
def start(self):
raise NotImplementedError()
@abc.abstractmethod
def stop(self):
raise NotImplementedError()
@abc.abstractmethod
def set(self, service, status):
"""Set the status of the given service.
Args:
service (str): service name of the service to set the reported status of
status (HealthStatus): status to set for the specified service
"""
raise NotImplementedError()
class _HealthServerImplementation(HealthServer):
"""Implementation for the reference gRPC Python health server."""
def __init__(self, server, servicer):
self._server = server
self._servicer = servicer
def start(self):
self._server.start()
def stop(self):
self._server.stop()
def set(self, service, status):
self._servicer.set(service, status)
def create_Health_server(port, private_key=None, certificate_chain=None):
"""Get a HealthServer instance.
Args:
port (int): port number passed through to health_pb2 server creation
routine.
private_key (str): to-be-created server's desired private key
certificate_chain (str): to-be-created server's desired certificate chain
Returns:
An instance of HealthServer (conforming thus to
EarlyAdopterHealthServer and providing a method to set server status)."""
servicer = _HealthServicer()
server = health_pb2.early_adopter_create_Health_server(
servicer, port=port, private_key=private_key,
certificate_chain=certificate_chain)
return _HealthServerImplementation(server, servicer)
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