I am trying to convert from flask-sockets but I used blueprints before, having so many routes in my project for normal webpages, and multiple uses of websockets.

I tried simply replacing my flask-sockets import with flask-sock, but get this error:

    sockets.register_blueprint(vnc.vnc_bp, url_prefix=r'/')
AttributeError: 'Sock' object has no attribute 'register_blueprint'

how can I proceed?

Like title, the error

"TypeError: init() got an unexpected keyword argument 'websocket'"

will prompt up out of random, i checked its not my code syntax error or what not, because when i restart my server, its worked again

Here is the stack trace after i ran 'flask run --host=0.0.0.0'

` * Serving Flask app "./run.py"

• Environment: production WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
• Debug mode: off Traceback (most recent call last): File "/usr/bin/flask", line 11, in load_entry_point('Flask==1.1.1', 'console_scripts', 'flask')() File "/usr/lib/python3/dist-packages/flask/cli.py", line 966, in main cli.main(prog_name="python -m flask" if as_module else None) File "/usr/lib/python3/dist-packages/flask/cli.py", line 586, in main return super(FlaskGroup, self).main(*args, **kwargs) File "/usr/lib/python3/dist-packages/click/core.py", line 717, in main rv = self.invoke(ctx) File "/usr/lib/python3/dist-packages/click/core.py", line 1137, in invoke return _process_result(sub_ctx.command.invoke(sub_ctx)) File "/usr/lib/python3/dist-packages/click/core.py", line 956, in invoke return ctx.invoke(self.callback, **ctx.params) File "/usr/lib/python3/dist-packages/click/core.py", line 555, in invoke return callback(*args, **kwargs) File "/usr/lib/python3/dist-packages/click/decorators.py", line 64, in new_func return ctx.invoke(f, obj, *args, **kwargs) File "/usr/lib/python3/dist-packages/click/core.py", line 555, in invoke return callback(*args, **kwargs) File "/usr/lib/python3/dist-packages/flask/cli.py", line 848, in run_command app = DispatchingApp(info.load_app, use_eager_loading=eager_loading) File "/usr/lib/python3/dist-packages/flask/cli.py", line 305, in init self._load_unlocked() File "/usr/lib/python3/dist-packages/flask/cli.py", line 330, in _load_unlocked self._app = rv = self.loader() File "/usr/lib/python3/dist-packages/flask/cli.py", line 388, in load_app app = locate_app(self, import_name, name) File "/usr/lib/python3/dist-packages/flask/cli.py", line 240, in locate_app import(module_name) File "/home/ubuntu/f3_portal/run.py", line 2, in app = create_app() File "/home/ubuntu/f3_portal/f3portal/init.py", line 40, in create_app import f3portal.socket.api File "/home/ubuntu/f3_portal/f3portal/socket/api.py", line 10, in def instance_state(ws): File "/home/ubuntu/.local/lib/python3.8/site-packages/flask_sock/init.py", line 31, in decorator return (self.app or self.bp).route(path, **kwargs)(websocket_route) File "/usr/lib/python3/dist-packages/flask/app.py", line 1314, in decorator self.add_url_rule(rule, endpoint, f, **options) File "/usr/lib/python3/dist-packages/flask/app.py", line 98, in wrapper_func return f(self, *args, **kwargs) File "/usr/lib/python3/dist-packages/flask/app.py", line 1274, in add_url_rule rule = self.url_rule_class(rule, methods=methods, **options) TypeError: init() got an unexpected keyword argument 'websocket'`

if try to simulate this error, it would not generate, this appear out of random

I have a flask-sock app deployed using gunicorn and nginx. I get disconnected after 10 minutes (sometimes sooner) with the following error: Disconnected (code: 1006, reason: "")

Is there a way to configure the timeout length?

I'm running it with: gunicorn --bind 127.0.0.1:5655 --workers 4 --threads 20 wsgi:app

I've been using this package for some time and it works very well. I'm still trying to determine the best way to close a websocket connection using ws.close(). After a connection is made by a client and the data has finished being sent, I get this error on the server side (full stack trace below):

wsproto.utilities.LocalProtocolError: Connection cannot be closed in state ConnectionState.CLOSED

Here is the code to reproduce this error. I'm running Python 3.8.5 on Ubuntu.

$ mkdir flask-sock-example
$ cd flask-sock-example
$ python3 -m venv env
$ source env/bin/activate
$ pip install Flask==1.1.2 flask-sock==0.3.0 "werkzeug>=2.0.0rc3"
$ pip freeze
click==8.0.0
Flask==1.1.2
flask-sock==0.3.0
h11==0.12.0
itsdangerous==2.0.0
Jinja2==3.0.0
MarkupSafe==2.0.0
simple-websocket==0.1.0
Werkzeug==2.0.0
wsproto==1.0.0

In a file called app.py:

from flask import Flask
from flask_sock import Sock
import time

app = Flask(__name__)
sock = Sock(app)

@sock.route('/stream')
def stream(ws):
    for i in range(3):
        ws.send(i)
        time.sleep(1)

    ws.close()

I use flask run to start the application. In another tab, I'm using wscat to connect to the websocket on localhost:

$ wscat -c ws://127.0.0.1:5000/stream
Connected (press CTRL+C to quit)
< 0
< 1
< 2
Disconnected (code: 1000, reason: "")
$ 

This works fine, however on the server side I get the aforementioned error:

 $ flask run
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [14/May/2021 12:57:09] "GET /stream HTTP/1.1" 200 -
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/home/imrankhan/flask-sock-example/env/lib/python3.8/site-packages/simple_websocket/ws.py", line 89, in _thread
    self.connected = self._handle_events()
  File "/home/imrankhan/flask-sock-example/env/lib/python3.8/site-packages/simple_websocket/ws.py", line 99, in _handle_events
    out_data += self.ws.send(event.response())
  File "/home/imrankhan/flask-sock-example/env/lib/python3.8/site-packages/wsproto/__init__.py", line 62, in send
    data += self.connection.send(event)
  File "/home/imrankhan/flask-sock-example/env/lib/python3.8/site-packages/wsproto/connection.py", line 99, in send
    raise LocalProtocolError(
wsproto.utilities.LocalProtocolError: Connection cannot be closed in state ConnectionState.CLOSED

Alternatively, if I remove the ws.close() line, I don't get an error on the server, instead I see this on the client:

$ wscat -c ws://127.0.0.1:5000/stream
Connected (press CTRL+C to quit)
< 0
< 1
< 2
error: Invalid WebSocket frame: RSV1 must be clear
> $ 

The popular flask-sockets project has recently been archived. It seems like this project should be its spiritual successor.

@edmorley, would it be appropriate to direct people to this project given that no one seems to have forked flask-sockets in order to continue maintaining it?

Hi Miguel, I have a Flask route which accepts a POST request with a parameters. Given one of the parameters is 'hello', is it possible to ws.send this 'hello' string to one of the connected ws clients? My app is purely server to client messages. Thanks!

Hello,

I am trying to run flask-sock over a GCP AppEngine instance. When running the script over it I am having multiple issue:

 Uncaught DOMException: Failed to execute 'send' on 'WebSocket': Still in CONNECTING state.
    at HTMLDocument.<anonymous> 

In the HTML header I have: <script>const socket = new WebSocket('wss://' + 'specificdomain.ey.r.appspot.com:8080' + '/customdimfrom0');</script>

I am running the script over a appspot.com subdomain (generated by google) And no error from the console to help find out the current problem.

I am sure it's the way on how the websocket connect to the appengine instance and I am clueless on how to fix this so far. (been trying

Any tips or similar issue when running the library over appengine instance ? Is there additional configuration on the appengine to accept incoming websocket? or maybe need to update the current url to initiate a websocket to the backend.

Thanks !

I am trying to keep track of connected clients and send messages to them. I connect with one client, store its websocket in memory, and then disconnect. I then connect with another client and try to interact with the websocket of the previous client that is no longer open.

When receive or send are called on a websocket that is already closed, the current connection closes with 1000 Normal Closure. What I would expect is an exception to be thrown so that I can catch it, remove the dead websocket object, and continue on with the current websocket.

I have included code to reproduce this issue and example output.

app.py

clients = []


@sock.route("/test")
def test(ws):
    global clients

    clients.append(ws)
    print(clients, flush=True)

    while True:
        print("Waiting to receive data...", flush=True)
        data = clients[0].receive()
        print("...done", flush=True)
        clients[0].send(data)

Client

$ wscat --connect 'ws://localhost:5000/test'
Connected (press CTRL+C to quit)
> hello, world
< hello, world
> $ ^C
$ wscat --connect 'ws://localhost:5000/test'
Connected (press CTRL+C to quit)
Disconnected (code: 1000, reason: "")
$ 

STDOUT

api_1  | [<simple_websocket.ws.Server object at 0x7fc2af10e640>]
api_1  | Waiting to receive data...
api_1  | ...done
api_1  | Waiting to receive data...
api_1  | [<simple_websocket.ws.Server object at 0x7fc2af10e640>, <simple_websocket.ws.Server object at 0x7fc2af17a610>]
api_1  | Waiting to receive data...
api_1  | 172.18.0.1 - - [03/Oct/2021 01:39:55] "GET /test HTTP/1.1" 200 -

I'm using this lovely library to facilitate socket communication. I really like this because it's so light. However, I ran into an issue where I've noticed that resources are not being released.

Issue

I was running a server for an extended period of time and repeatedly opening and close the page. It got to a point where the server started throwing "too many files open errors". I looked more into this and found that there are a lot of eventpoll handles open. This can be seen using the lsof command on the PID of the flask processes.

COMMAND   PID  USER   FD      TYPE     DEVICE SIZE/OFF    NODE NAME
...
python  26774 chris   15u  a_inode       0,13        0    7189 [eventpoll]

Repro

Create basic setup for web socket.

Files:

# app.py

from flask import Flask, render_template
from flask_sock import Sock


app = Flask(__name__)
sock = Sock(app)


@app.route("/")
def main() -> str:
  return render_template("main.html")

@sock.route("/echo")
def echo(ws) -> None:
  try:
    while True:
      data = ws.receive()
      ws.send(data)
  finally:
    print("echo end")

# main.html
<!doctype html>
<html lang="en"><head></head><body>
<script>

      let ws = new WebSocket(`ws://${location.host}/echo`);
      ws.onopen = () => {
        ws.send("test");
      }
</script>
</body></html>

Steps:

1. Open the webpage and close it.
2. On the server, after every time the page gets opened, use the following command to count eventpoll handles:

function countpoll {
  for p in $(pgrep -f "flask run"); do
    lsof -p $p | grep eventpoll | wc -l
  done;
}

You'll see the number go up after every time the page gets reloaded.

System Info

I've reproduced this issue on Ubuntu and Raspian OS environments.

I'm using Python 3.9.2

Here's the Python packages I'm using.

flask-sock==0.5.2
python-socketio==5.7.2
simple-websocket==0.8.1
websockets==10.4

I have a frontend/backend set up that uses flask-sock and works well when I start my application with:

FLASK_APP=backend FLASK_ENV=development flask run

However, when I try to start my application using the API of python-livereload as follows:

from backend import app
from livereload import Server, shell

if __name__ == '__main__':
    app.debug = True
    server = Server(app.wsgi_app)
    server.watch('backend/static')
    server.serve(port=5000)

I am getting the following back trace:

[E 220719 13:44:59 web:1798] Uncaught exception GET /stream (127.0.0.1)
    HTTPServerRequest(protocol='http', host='localhost:5000', method='GET', uri='/stream', version='HTTP/1.1', remote_ip='127.0.0.1')
    Traceback (most recent call last):
      File "/usr/local/lib/python3.8/dist-packages/tornado/web.py", line 1690, in _execute
        result = self.prepare()
      File "/usr/local/lib/python3.8/dist-packages/tornado/web.py", line 3056, in prepare
        self.fallback(self.request)
      File "/usr/local/lib/python3.8/dist-packages/livereload/server.py", line 112, in __call__
        app_response = self.wsgi_app(
      File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 2076, in wsgi_app
        response = self.handle_exception(e)
      File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 2073, in wsgi_app
        response = self.full_dispatch_request()
      File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1519, in full_dispatch_request
        rv = self.handle_user_exception(e)
      File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1517, in full_dispatch_request
        rv = self.dispatch_request()
      File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1503, in dispatch_request
        return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
      File "/usr/local/lib/python3.8/dist-packages/flask_sock/__init__.py", line 56, in websocket_route
        ws = Server(request.environ, **current_app.config.get(
      File "/usr/local/lib/python3.8/dist-packages/simple_websocket/ws.py", line 301, in __init__
        raise RuntimeError('Cannot obtain socket from WSGI environment.')
    RuntimeError: Cannot obtain socket from WSGI environment.

I am not sure how to interpret the error Cannot obtain socket from WSGI environment. As far as I understand, when I use flask run, I am using the Werkzeug framework which is supported by flask-sock and from the back trace python-livereload is using Tornado which perhaps is not supported?

This is all a bit confusing since from #29 it is mentioned:

Flask-Sock uses its own WebSocket implementation (provided by the wsproto package) instead of relying on the web server's own WebSocket support

So I would have thought that it did not matter what underlying framework is being used...

The example code does not work.

I have tried running the code in the example folder and have received the following error:

Firefox can’t establish a connection to the server at ws://localhost:5000/echo.

However, the following command does work:

wscat --connect ws://localhost:5000/echo

I have installed the following Python packages:

$ pip freeze
click==8.0.0
colorama==0.4.4
Flask==2.0.0
flask-sock==0.3.0
h11==0.12.0
itsdangerous==2.0.0
Jinja2==3.0.0
MarkupSafe==2.0.0
simple-websocket==0.2.0
Werkzeug==2.0.0
wsproto==1.0.0

I tried copying your example (https://blog.miguelgrinberg.com/post/add-a-websocket-route-to-your-flask-2-x-application) and it just spams the page with this rendering the entire browser unresponsive. Any idea why?

Hi, my understanding is that this only works with the Flask dev server, and with gunicorn.

How can one extend this to work with uwsgi too?

I got flask-socketio working with uwsgi (and gevent) doing something like:

uwsgi --module app:app  --touch-reload app.py  --master  --http :8000  --http-websockets  --gevent 1024

but (unsurprisingly) the same thing doesn't work with flask-sock, probably because support for uwsgi needs to be specifically implemented. (But how?)

Hi Miguel,

i have an issue with flask-sock in an containerized application. As I tested my app in a local environment, everything works as expected, the javascript in my html-doc connects properly and the communication runs continuously.

But now I switched to an containerized environment using gunicorn as webserver started by supervisor and now the server returns always a 404 as the html doc calls the websocket. I tried several configs to figure out what's happening, but I have no more ideas what to do.

Here are the crucial parts of code, config and log:

app.py

...
app = flask.Flask(
    __name__,
    static_folder = '/www/static'
)

ws = flask_sock.Sock()
...

def create_app():
    ...
    app.config['SOCK_SERVER_OPTIONS'] = {
        'ping_interval' : 5
    }
    ...
    ws.init_app(app)
    ...
    from .views import default
    ... 
    return app

default.py

@ws.route('/api/ws')
def wsapi(ws):
    app.logger.info('ws call')
    while True:
        time.sleep(1)
        ws.send('Hello')
        app.logger.info('ws cycle')

index.html

            const ws = new WebSocket('ws://'+location.host+'/api/ws');

            ws.addEventListener('open', ev => {
                console.log('WS OPENED!');
            });

            ws.addEventListener('close', ev => {
                console.log('WS CLOSED!');
            });

            ws.addEventListener('message', ev => {
                console.log(ev.data)
            });

supervisord.conf

...
[program:gunicorn]
command=/www/venv/bin/gunicorn wsgi:app -b :80 --reload -k geventwebsocket.gunicorn.workers.GeventWebSocketWorker --workers 4 --threads 100
directory=/www/app
user=www-data
group=www-data
autostart=true
autorestart=true
stdout_logfile=/dev/stdout
stdout_logfile_maxbytes=0
stderr_logfile=/dev/stderr
stderr_logfile_maxbytes=0
...

log (generated with app.before_request & app.after_request)

[2022-05-12 08:23:59,915] INFO in app: <Request 'http://10.1.7.3:9500/api/ws' [GET]>
[2022-05-12 08:23:59,917] INFO in app: <Response streamed [404 NOT FOUND]>

Maybe you have some hints for me, how to use your flask-extension properly.

Cheers, Carsten