failed to connect to all addresses

[valentinc94]

https://djangogrpcframework.readthedocs.io/en/latest/quickstart.html

I did this tutorial but when executing this:

with grpc.insecure_channel('localhost:50051') as channel:
stub = account_pb2_grpc.UserControllerStub(channel)
for user in stub.List(account_pb2.UserListRequest()):
print(user, end='')

always return

grpc._channel._MultiThreadedRendezvous: <_MultiThreadedRendezvous of RPC that terminated with:
status = StatusCode.UNAVAILABLE
details = "failed to connect to all addresses"
debug_error_string = "{"created":"@1605744210.127297754","description":"Failed to pick subchannel","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":4165,"referenced_errors":[{"created":"@1605744210.127291858","description":"failed to connect to all addresses","file":"src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.cc","file_line":397,"grpc_status":14}]}"

i have a docker for this project

version: '3'

services:
db:
image: postgres
env_file:
- ./backend/.env
ports:
- "6543:5432"
networks:
- webappnetwork
backend:
build: ./backend
volumes:
- ./backend/:/code
env_file:
- ./backend/.env
ports:
- "8000:8000"
command: python manage.py runserver 0.0.0.0:8000
depends_on:
- db
networks:
- webappnetwork
grpc:
build: ./backend
volumes:
- ./backend/:/code
env_file:
- ./backend/.env
ports:
- "50051:50051"
command: python manage.py grpcrunserver --dev
depends_on:
- db
- backend
networks:
- webappnetwork

networks:
webappnetwork:
driver: bridge

volumes:
database-data:
pgadmin-data: