How to fix Python WebSocket ValueError: scheme http is invalid

Problem:

You want to use Python to connect to your WebSocket server:

import websocket
ws = websocket.WebSocket()
ws.connect("http://192.168.1.211/ws")

But you see an error message like

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-2-5108525d0b43> in <module>
      1 import websocket
      2 ws = websocket.WebSocket()
----> 3 ws.connect("http://10.228.152.103/ws")
      4 while True:
      5     result = ws.recv()

c:\python38\lib\site-packages\websocket_core.py in connect(self, url, **options)
    220         # FIXME: "header", "cookie", "origin" and "host" too
    221         self.sock_opt.timeout = options.get('timeout', self.sock_opt.timeout)
--> 222         self.sock, addrs = connect(url, self.sock_opt, proxy_info(**options),
    223                                    options.pop('socket', None))
    224 

c:\python38\lib\site-packages\websocket_http.py in connect(url, options, proxy, socket)
    106         return _open_proxied_socket(url, options, proxy)
    107 
--> 108     hostname, port, resource, is_secure = parse_url(url)
    109 
    110     if socket:

c:\python38\lib\site-packages\websocket_url.py in parse_url(url)
     61             port = 443
     62     else:
---> 63         raise ValueError("scheme %s is invalid" % scheme)
     64 
     65     if parsed.path:

ValueError: scheme http is invalid

Solution

The websocket-client library wants you to use ws://host/path instead of http://host/path. So instead of

ws.connect("http://10.228.152.103/ws")

use

ws.connect("http://10.228.152.103/ws")