Weird behavior on AWS beanstalk deployment

[RodrigoNeves95]

I'm kinda running out of ideas and getting desperate at the same time ahah. I also don't know if this is the correct place but here it goes:

Trying to deploy a flask web-app using flask-socketio over a Docker AWS Beanstalk deployment. gevent is being used to serve the web app:

Note 1: The deployment used an AWS Application load balancer and entry point with a certificate and routes the traffic to a EC2 instance where a nginx server is running on port 80 to get the request and proxy them to the docker on port 5000 - This is the normal flow of the AWS Beanstalk stack

Note: no configuration at all was made to the nginx on the EC2 instnace

CMD ["gunicorn", "--bind", "0.0.0.0:5000","--workers","1", "--threads", "1", "application:application", "-k", "geventwebsocket.gunicorn.workers.GeventWebSocketWorker", "--timeout", "180"]

First weird thing:

From the client if I do not force the protocol to to only use WebSocket I can't make the server go from polling to WebSocket. I get a 400 on the request. If I force to use Webscocket from the client I can make the ws protocol work.

Second weird thing:

If I actually remove gevent-websocket requirement and start the server with a gevent worker the server can make the request over polling, with no problem at all.

Third weird thing:

If I run the server with gevent-websocket support and force the client to run with ws only (to make sure I can actually use webscokets) I can run the web app normally, except for one tiny little thing that is driving me crazy: The first request to the server (after the login) is getting a 400 regardless of what I do. And this request is a normal HTTP GET method. All the requests after that first one, runs normally.

I'm also getting this weird things on the server output

<gevent._socket3.socket at 0x7fd3c5d2c1c0 object, fd=14, family=2, type=1, proto=6>: Invalid HTTP method: '3ff5ce1-583e6c977c0b74f445ff044d\r\n' 

I have no idea what this is and where it comes from

Happy to present all info needed

[miguelgrinberg]

I also don't know if this is the correct place but here it goes:

No. It's not good to file a bug when you just have questions. Use the discussions board for questions. I have transferred it for you this time.

From the client if I do not force the protocol to to only use WebSocket I can't make the server go from polling to WebSocket. I get a 400 on the request. If I force to use Webscocket from the client I can make the ws protocol work.

This is expected when you use a load balancing solution that is not compliant with the requirements of Socket.IO. See
using multiple workers in the documentation for these requirements.

If I actually remove gevent-websocket requirement and start the server with a gevent worker the server can make the request over polling, with no problem at all.

I don't see what relation gevent-websocket vs gevent standard worker can have on this, so I don't have an explanation for this other than you changed something else without realizing it.

If I run the server with gevent-websocket support and force the client to run with ws only (to make sure I can actually use webscokets) I can run the web app normally, except for one tiny little thing that is driving me crazy: The first request to the server (after the login) is getting a 400 regardless of what I do. And this request is a normal HTTP GET method. All the requests after that first one, runs normally.

I don't understand this. If you are connecting with WebSocket, then there is only one request per connection. No idea what other requests your client is sending, but if you are using WebSocket they cannot be related to Socket.IO.

[RodrigoNeves95]

As I was expecting I never ran the server with more than one worker. Check the server output logs after starting explicitly with one worker and making a login and logout twice

That weird socket print appears every time we get the 400.

I also tried locally not using gevent-websocket (running everything with polling, and not trying the upgrade) and the 400 does not happen. Something that you can remember from gevent-websocket that is making this happening?

[miguelgrinberg]

I'm sorry, I think I may have not been very clear. When I referred to the 400 errors I meant errors coming from the Socket.IO side. This is not a Socket.IO error, this is some issue on the gevent-websocket library, which I'm not surprised of since it hasn't been regularly maintained in a long time. You can try using eventlet, which has its own internal WebSocket server.

[RodrigoNeves95]

Thanks for the feedback and answers. I will give it a try and report back then.

This is not a blocker for me, because after the first 400 everything just works for the session, but nevertheless, I found this super weird.

Thanks for the support

[RodrigoNeves95]

Finally got the time to remove gevent + gevent-webscoket and use eventlet.

Everything works. I had to do it because things got unusable. So I initially thought that we would only get an initial 400. But actually, I would get an 400 error everytime after a POST request (yeah I have no idea as well)

I will assume gevent-websocket is just broken.

[RodrigoNeves95]

I think we can close this