Chameleon fault tolerance
Change-Id: Id7060f121f85a444005dfeff6279daef51a59295
diff --git a/asleep.py b/asleep.py
new file mode 100644
index 0000000..e1868ab
--- /dev/null
+++ b/asleep.py
@@ -0,0 +1,27 @@
+#
+# Copyright 2016 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+""" Async sleep (asleep) method and other twisted goodies """
+
+from twisted.internet import reactor
+from twisted.internet.defer import Deferred
+
+
+def asleep(dt):
+ assert isinstance(dt, (int, float))
+ d = Deferred()
+ reactor.callLater(dt, lambda: d.callback(None))
+ return d
diff --git a/grpc_client/grpc_client.py b/grpc_client/grpc_client.py
index c2d66db..72c8e47 100644
--- a/grpc_client/grpc_client.py
+++ b/grpc_client/grpc_client.py
@@ -15,11 +15,11 @@
#
"""
-gRPC client meant to connect to a gRPC server endpoint,
-and query the end-point's schema by calling
-SchemaService.Schema(NullMessage) and all of its
+gRPC client meant to connect to a gRPC server endpoint, and query the
+end-point's schema by calling SchemaService.Schema(NullMessage) and all of its
semantics are derived from the recovered schema.
"""
+
import os
import sys
from random import randint
@@ -27,14 +27,25 @@
import grpc
from consul import Consul
+from grpc._channel import _Rendezvous
from structlog import get_logger
+from twisted.internet import reactor
+from twisted.internet.defer import inlineCallbacks
+from werkzeug.exceptions import ServiceUnavailable
+from chameleon.asleep import asleep
from chameleon.protos.schema_pb2 import NullMessage, SchemaServiceStub
log = get_logger()
class GrpcClient(object):
+ """
+ Connect to a gRPC server, fetch its schema, and process the downloaded
+ schema files to drive the customization of the north-bound interface(s)
+ of Chameleon.
+ """
+ RETRY_BACKOFF = [0.05, 0.1, 0.2, 0.5, 1, 2, 5]
def __init__(self, consul_endpoint, work_dir, endpoint='localhost:50055'):
self.consul_endpoint = consul_endpoint
@@ -45,11 +56,13 @@
self.channel = None
self.schema = None
-
+ self.retries = 0
+ self.on_reconnect = None
self.shutting_down = False
- def run(self):
- self.connect()
+ def run(self, on_reconnect=None):
+ self.on_reconnect = on_reconnect
+ reactor.callLater(0, self.connect)
return self
def shutdown(self):
@@ -58,14 +71,18 @@
self.shutting_down = True
pass
+ @inlineCallbacks
def connect(self):
- """(re-)connect to end-point"""
+ """
+ (Re-)Connect to end-point
+ """
+
if self.shutting_down:
return
try:
if self.endpoint.startswith('@'):
- _endpoint = self.get_endpoint_from_consul(self.endpoint[1:])
+ _endpoint = self._get_endpoint_from_consul(self.endpoint[1:])
else:
_endpoint = self.endpoint
@@ -74,13 +91,43 @@
self._retrieve_schema()
self._compile_proto_files()
+ self._clear_backoff()
+
+ if self.on_reconnect is not None:
+ reactor.callLater(0, self.on_reconnect)
+
+ return
+
+ except _Rendezvous, e:
+ if e.code() == grpc.StatusCode.UNAVAILABLE:
+ log.info('grpc-endpoint-not-available')
+ else:
+ log.exception(e)
+ yield self._backoff('not-available')
except Exception, e:
- log.exception('cannot-connect', endpoint=_endpoint)
+ if not self.shutting_down:
+ log.exception('cannot-connect', endpoint=_endpoint)
+ yield self._backoff('unknown-error')
- def get_endpoint_from_consul(self, service_name):
- """Look up an appropriate grpc endpoint (host, port) from
- consul, under the service name specified by service-name
+ reactor.callLater(0, self.connect)
+
+ def _backoff(self, msg):
+ wait_time = self.RETRY_BACKOFF[min(self.retries,
+ len(self.RETRY_BACKOFF) - 1)]
+ self.retries += 1
+ log.error(msg, retry_in=wait_time)
+ return asleep(wait_time)
+
+ def _clear_backoff(self):
+ if self.retries:
+ log.info('reconnected', after_retries=self.retries)
+ self.retries = 0
+
+ def _get_endpoint_from_consul(self, service_name):
+ """
+ Look up an appropriate grpc endpoint (host, port) from
+ consul, under the service name specified by service-name
"""
host = self.consul_endpoint.split(':')[0].strip()
port = int(self.consul_endpoint.split(':')[1].strip())
@@ -100,10 +147,19 @@
return endpoint
def _retrieve_schema(self):
- """Retrieve schema from gRPC end-point"""
+ """
+ Retrieve schema from gRPC end-point, and save all *.proto files in
+ the work directory.
+ """
assert isinstance(self.channel, grpc.Channel)
stub = SchemaServiceStub(self.channel)
+ # try:
schema = stub.GetSchema(NullMessage())
+ # except _Rendezvous, e:
+ # if e.code == grpc.StatusCode.UNAVAILABLE:
+ #
+ # else:
+ # raise e
os.system('mkdir -p %s' % self.work_dir)
os.system('rm -fr /tmp/%s/*' %
@@ -124,7 +180,12 @@
f.write(content)
def _compile_proto_files(self):
-
+ """
+ For each *.proto file in the work directory, compile the proto
+ file into the respective *_pb2.py file as well as generate the
+ web server gateway python file *_gw.py.
+ :return: None
+ """
google_api_dir = os.path.abspath(os.path.join(
os.path.dirname(__file__),
'../protos/third_party'
@@ -132,8 +193,8 @@
for fname in [f for f in os.listdir(self.work_dir)
if f.endswith('.proto')]:
- log.info('compiling', file=fname)
+ log.debug('compiling', file=fname)
cmd = (
'cd %s && '
'env PATH=%s PYTHONPATH=%s '
@@ -152,8 +213,9 @@
self.plugin_dir,
fname)
)
- log.debug('executing', cmd=cmd)
+ log.debug('executing', cmd=cmd, file=fname)
os.system(cmd)
+ log.info('compiled', file=fname)
# test-load each _pb2 file to see all is right
if self.work_dir not in sys.path:
@@ -166,5 +228,28 @@
_ = __import__(modname)
def invoke(self, stub, method_name, request):
- response = getattr(stub(self.channel), method_name)(request)
- return response
+ """
+ Invoke a gRPC call to the remote server and return the response.
+ :param stub: Reference to the *_pb2 service stub
+ :param method_name: The method name inside the service stub
+ :param request: The request protobuf message
+ :return: The response protobuf message
+ """
+
+ if self.channel is None:
+ raise ServiceUnavailable()
+
+ try:
+ response = getattr(stub(self.channel), method_name)(request)
+ return response
+
+ except grpc._channel._Rendezvous, e:
+ if e.code() == grpc.StatusCode.UNAVAILABLE:
+ e = ServiceUnavailable()
+ else:
+ log.exception(e)
+
+ self.channel = None
+ reactor.callLater(0, self.connect)
+
+ raise e
diff --git a/main.py b/main.py
index 470dc84..3892dac 100755
--- a/main.py
+++ b/main.py
@@ -222,9 +222,11 @@
self.log.info('starting-internal-components')
args = self.args
self.grpc_client = yield \
- GrpcClient(args.consul, args.work_dir, args.grpc_endpoint).run()
+ GrpcClient(args.consul, args.work_dir, args.grpc_endpoint)
self.web_server = yield \
WebServer(args.rest_port, args.work_dir, self.grpc_client).run()
+ self.grpc_client.run(
+ on_reconnect=self.web_server.reload_generated_routes)
self.log.info('started-internal-services')
@inlineCallbacks
diff --git a/web_server/web_server.py b/web_server/web_server.py
index af8c6c5..c46ad88 100644
--- a/web_server/web_server.py
+++ b/web_server/web_server.py
@@ -25,6 +25,7 @@
from twisted.internet.tcp import Port
from twisted.web.server import Site
from twisted.web.static import File
+from werkzeug.exceptions import BadRequest
log = get_logger()
@@ -43,23 +44,13 @@
os.path.join(os.path.dirname(__file__), '../swagger_ui'))
self.tcp_port = None
+ self.shutting_down = False
@inlineCallbacks
def run(self):
yield self._open_endpoint()
- yield self._load_generated_routes()
returnValue(self)
- def _load_generated_routes(self):
- for fname in os.listdir(self.work_dir):
- if fname.endswith('_gw.py'):
- module_name = fname.replace('.py', '')
- print 'module_name', module_name
- m = __import__(module_name)
- print dir(m)
- assert hasattr(m, 'add_routes')
- m.add_routes(self.app, self.grpc_client)
-
@inlineCallbacks
def _open_endpoint(self):
endpoint = endpoints.TCP4ServerEndpoint(reactor, self.port)
@@ -70,10 +61,20 @@
@inlineCallbacks
def shutdown(self):
- if self.tcp_porte is not None:
+ self.shutting_down = True
+ if self.tcp_port is not None:
assert isinstance(self.tcp_port, Port)
yield self.tcp_port.socket.close()
+ def reload_generated_routes(self):
+ for fname in os.listdir(self.work_dir):
+ if fname.endswith('_gw.py'):
+ module_name = fname.replace('.py', '')
+ m = __import__(module_name)
+ assert hasattr(m, 'add_routes')
+ m.add_routes(self.app, self.grpc_client)
+ log.info('routes-loaded', module=module_name)
+
# static swagger_ui website as landing page (for now)
@app.route('/', branch=True)