I am trying to follow the tutorial here
https://channels.readthedocs.io/en/latest/tutorial/part_2.html and check if channel layer can communicate with Redis. The only different thing I’m doing is that I’m using docker-compose and running the entire thing on a docker container, and that seems to be messing up with everything. This is the error message I’m getting when I try to
run async_to_sync(channel_layer.send)('test_channel', {'type': 'hello'})
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/lib/python3.7/site-packages/asgiref/sync.py", line 116, in __call__
return call_result.result()
File "/usr/local/lib/python3.7/concurrent/futures/_base.py", line 428, in result
return self.__get_result()
File "/usr/local/lib/python3.7/concurrent/futures/_base.py", line 384, in __get_result
raise self._exception
File "/usr/local/lib/python3.7/site-packages/asgiref/sync.py", line 156, in main_wrap
result = await self.awaitable(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/channels_redis/core.py", line 293, in send
async with self.connection(index) as connection:
File "/usr/local/lib/python3.7/site-packages/channels_redis/core.py", line 820, in __aenter__
self.conn = await self.pool.pop()
File "/usr/local/lib/python3.7/site-packages/channels_redis/core.py", line 70, in pop
conns.append(await aioredis.create_redis(**self.host, loop=loop))
File "/usr/local/lib/python3.7/site-packages/aioredis/commands/__init__.py", line 175, in create_redis
loop=loop)
File "/usr/local/lib/python3.7/site-packages/aioredis/connection.py", line 113, in create_connection
timeout)
File "/usr/local/lib/python3.7/asyncio/tasks.py", line 414, in wait_for
return await fut
File "/usr/local/lib/python3.7/site-packages/aioredis/stream.py", line 24, in open_connection
lambda: protocol, host, port, **kwds)
File "/usr/local/lib/python3.7/asyncio/base_events.py", line 958, in create_connection
raise exceptions[0]
File "/usr/local/lib/python3.7/asyncio/base_events.py", line 945, in create_connection
await self.sock_connect(sock, address)
File "/usr/local/lib/python3.7/asyncio/selector_events.py", line 473, in sock_connect
return await fut
File "/usr/local/lib/python3.7/asyncio/selector_events.py", line 503, in _sock_connect_cb
raise OSError(err, f'Connect call failed {address}')
ConnectionRefusedError: [Errno 111] Connect call failed ('127.0.0.1', 6379)
I’ve checked a few post and saw that many suggested this is because Redis isn’t running. I know that Redis exist since docker ps shows that
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2ccab2cfc570 test_web "python manage.py ru…" 7 minutes ago Up 7 minutes 0.0.0.0:8000->8000/tcp test_web_1
6da398f093fc redis:2.8 "docker-entrypoint.s…" 10 minutes ago Up 10 minutes 0.0.0.0:6379->6379/tcp relaxed_aryabhata
Any idea what I can do right now? I’m really new to these
9
Answers
Try changing
127.0.0.1:6379
toredis:6379
.Although Redis is running, your
python
container isn’t able to communicate with it; this is because it’s trying to connect to127.0.0.1:6379
, but from the container’s perspective, there’s nothing running there. This can be a bit frustrating to debug, but it’s a bit easier if you keep in mind that containers get their own network namespace. As a result,python
‘s localhost !=redis
‘s localhost != your host machine’slocalhost
.Luckily, it’s easy to connect containers that are sharing the same bridge, and by default,
docker-compose
creates a single bridge network and connects all your containers to them, providing the necessary DNS to allow them to discover one another. As a result, container-to-container communication works simply by using the service name.As a note, it’s possible to run containers in the same namespace, and to run in them in the namespace of the host, via the
--net=container:<container-id>
or--net=host
flag. This is especially useful for running debugging tools in a container and attaching them to the network namespace of either another container or the host, e.g. using netshoot to see what ports are listening within the container (exposed or not),docker run --rm -it --net container:test_web_1 nicolaka/netshoot netstat -tulpn
.and then start the server
i have the same issue,
the problem was the version of my python and also of the channels.
the tutorial woks perfectly with python=3.6, channels-redis 2.3.1 and daphne 2.0.2, channels =2.0.
You can follow the channels documentation of the channels version you have install.
So I got stuck on this and none of the answers seemed to work for me.
I found that docker would give the container its own IP address. to find the IP address in the command line I used;
‘docker ps’ to get the container ID.
‘docker inspect -f ‘{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}} * container-id*’ which gave me the IP.
This worked for;
it works for me. Just some details
docker-compose.yml
I had a similar error with a Python FastAPI app running in a Docker container trying to connect to another container with
http3.AsyncClient
which also usesasyncio
library.One option which worked was to use IP of a container to which trying to connect. Get container id with
docker ps
then get container’s IP with one of the options:The other was to run container on a
host
network which lets a container share your host’s networking stackthen
127.0.0.1
can be used for a host to connect to.Whether install Redis on your container manually and set it up with Django or set up docker-compose to do that for you.
or
My docker-compose.yml file
When you set up a service for redis the name of your service will be your host.
know more
Okay, my search query was ConnectionRefusedError: [Errno 111] Connect call failed (‘127.0.0.1’, 5432) and google took me here. So, if anyone is looking for that issue, assuming,
try,
Follow the Tutorial:
docker run -p 6379:6379 -d redis:5
before and then:
python3 manage.py runserver
If you restart your system you need to run docker run -p 6379:6379 -d redis:5 again before python3 manage.py runserver