Simple gRPC envoy configuration - grpc

Question

I'm trying to setup a envoy proxy as a gRPC fron end, and can't get it to work, so I'm trying to get to as simple a test setup as possible and build from there, but I can't get that to work either. Here's what my test setup looks like:
Python server (slightly modified gRPC example code)
# greeter_server.py
from concurrent import futures
import time
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
_ONE_DAY_IN_SECONDS = 60 * 60 * 24
class Greeter(helloworld_pb2_grpc.GreeterServicer):
def SayHello(self, request, context):
return helloworld_pb2.HelloReply(message='Hello, %s!' % request.name)
def serve():
server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
server.add_insecure_port('[::]:8081')
server.start()
try:
while True:
time.sleep(_ONE_DAY_IN_SECONDS)
except KeyboardInterrupt:
server.stop(0)
if __name__ == '__main__':
serve()
Python client (slightly modified gRPC example code)
from __future__ import print_function
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
def run():
# NOTE(gRPC Python Team): .close() is possible on a channel and should be
# used in circumstances in which the with statement does not fit the needs
# of the code.
with grpc.insecure_channel('localhost:9911') as channel:
stub = helloworld_pb2_grpc.GreeterStub(channel)
response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))
print("Greeter client received: " + response.message)
if __name__ == '__main__':
run()
And then my two envoy yaml files:
# envoy-hello-server.yaml
static_resources:
listeners:
- address:
socket_address:
address: 0.0.0.0
port_value: 8811
filter_chains:
- filters:
- name: envoy.http_connection_manager
typed_config:
"#type": type.googleapis.com/envoy.config.filter.network.http_connection_manager.v2.HttpConnectionManager
codec_type: auto
stat_prefix: ingress_http
access_log:
- name: envoy.file_access_log
typed_config:
"#type": type.googleapis.com/envoy.config.accesslog.v2.FileAccessLog
path: "/dev/stdout"
route_config:
name: local_route
virtual_hosts:
- name: backend
domains:
- "*"
routes:
- match:
prefix: "/"
grpc: {}
route:
cluster: hello_grpc_service
http_filters:
- name: envoy.router
typed_config: {}
clusters:
- name: hello_grpc_service
connect_timeout: 0.250s
type: strict_dns
lb_policy: round_robin
http2_protocol_options: {}
load_assignment:
cluster_name: hello_grpc_service
endpoints:
- lb_endpoints:
- endpoint:
address:
socket_address:
address: hello_grpc_service
port_value: 8081
admin:
access_log_path: "/tmp/envoy_hello_server.log"
address:
socket_address:
address: 0.0.0.0
port_value: 8881
and
# envoy-hello-client.yaml
static_resources:
listeners:
- address:
socket_address:
address: 0.0.0.0
port_value: 9911
filter_chains:
- filters:
- name: envoy.http_connection_manager
typed_config:
"#type": type.googleapis.com/envoy.config.filter.network.http_connection_manager.v2.HttpConnectionManager
codec_type: auto
add_user_agent: true
access_log:
- name: envoy.file_access_log
typed_config:
"#type": type.googleapis.com/envoy.config.accesslog.v2.FileAccessLog
path: "/dev/stdout"
stat_prefix: egress_http
common_http_protocol_options:
idle_timeout: 0.840s
use_remote_address: true
route_config:
name: local_route
virtual_hosts:
- name: backend
domains:
- grpc
routes:
- match:
prefix: "/"
route:
cluster: backend-proxy
http_filters:
- name: envoy.router
typed_config: {}
clusters:
- name: backend-proxy
type: logical_dns
dns_lookup_family: V4_ONLY
lb_policy: round_robin
connect_timeout: 0.250s
http_protocol_options: {}
load_assignment:
cluster_name: backend-proxy
endpoints:
- lb_endpoints:
- endpoint:
address:
socket_address:
address: hello_grpc_service
port_value: 8811
admin:
access_log_path: "/tmp/envoy_hello_client.log"
address:
socket_address:
address: 0.0.0.0
port_value: 9991
Now, what I expect this would allow is something like hello_client.py (port 9911) -> envoy (envoy-hello-client.yaml) -> envoy (envoy-hello-server.yaml) -> hello_server.py (port 8081)
Instead, what I get is an error from the python client:
$ python3 greeter_client.py
Traceback (most recent call last):
File "greeter_client.py", line 35, in <module>
run()
File "greeter_client.py", line 30, in run
response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))
File "/usr/lib/python3/dist-packages/grpc/_channel.py", line 533, in __call__
return _end_unary_response_blocking(state, call, False, None)
File "/usr/lib/python3/dist-packages/grpc/_channel.py", line 467, in _end_unary_response_blocking
raise _Rendezvous(state, None, None, deadline)
grpc._channel._Rendezvous: <_Rendezvous of RPC that terminated with:
status = StatusCode.UNIMPLEMENTED
details = ""
debug_error_string = "{"created":"#1594770575.642032812","description":"Error received from peer","file":"src/core/lib/surface/call.cc","file_line":1017,"grpc_message":"","grpc_status":12}"
>
And in the envoy client log:
[2020-07-14 16:22:10.407][16935][info][main] [external/envoy/source/server/server.cc:652] starting main dispatch loop
[2020-07-14 16:23:25.441][16935][info][runtime] [external/envoy/source/common/runtime/runtime_impl.cc:524] RTDS has finished initialization
[2020-07-14 16:23:25.441][16935][info][upstream] [external/envoy/source/common/upstream/cluster_manager_impl.cc:182] cm init: all clusters initialized
[2020-07-14 16:23:25.441][16935][info][main] [external/envoy/source/server/server.cc:631] all clusters initialized. initializing init manager
[2020-07-14 16:23:25.441][16935][info][config] [external/envoy/source/server/listener_manager_impl.cc:844] all dependencies initialized. starting workers
[2020-07-14 16:23:25.441][16935][warning][main] [external/envoy/source/server/server.cc:537] there is no configured limit to the number of allowed active connections. Set a limit via the runtime key overload.global_downstream_max_connections
[2020-07-14T23:49:35.641Z] "POST /helloworld.Greeter/SayHello HTTP/2" 200 NR 0 0 0 - "10.0.0.56" "grpc-python/1.16.1 grpc-c/6.0.0 (linux; chttp2; gao)" "aa72310a-3188-46b2-8cbf-9448b074f7ae" "localhost:9911" "-"
And nothing in the server log.
Also, weirdly, this is an almost one second delay between when I run the python client and when the log message shows up in the client envoy.
What am I missing to make these two scripts talk via envoy?

Answer 1

I know I'm bit late, hope this helps someone. Since you are grpc server is running in the same host you could specify hostname to be host.docker.internal (previous docker.for.mac.localhost deprecated from docker v18.03.0)
In your case if you are running in a dockerized environment you could do the following:
Envoy version: 1.13+
clusters:
- name: backend-proxy
type: logical_dns
dns_lookup_family: V4_ONLY
lb_policy: round_robin
connect_timeout: 0.250s
http_protocol_options: {}
load_assignment:
cluster_name: backend-proxy
endpoints:
- lb_endpoints:
- endpoint:
address:
socket_address:
address: host.docker.internal
port_value: 8811
hello_grpc_service won't be resolved to IP in dockerized environment.
Note: you could enable envoy trace log level for detailed logs