Action cable unable to connect (Failed to upgrade to WebSocket )
<p>I am having a issue in connecting to websocket in non-development environments with these log messages </p>

<pre><code>Failed to upgrade to WebSocket (REQUEST_METHOD: GET, HTTP_CONNECTION: close, HTTP_UPGRADE: )

Finished "/cable/"[non-WebSocket] for 127.0.0.1 at 2016-07-06 09:44:29 +1000
</code></pre>

<p>I debuggged a little and figured out the request sent by the browser/javascript is not exactly the same as the request received by unicorn(running with nginx).</p>

<p>The request header by the browser is</p>

<pre><code>GET ws://cc-uat.com.au/cable HTTP/1.1
Host: cc-uat.com.au
Connection: Upgrade
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket
Origin: http://cc-uat.com.au
Sec-WebSocket-Version: 13
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Cookie: &lt;Lot of cookies&gt;
Sec-WebSocket-Key: QGdJkYIA2u7vtmMVXfHKtQ==
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
Sec-WebSocket-Protocol: actioncable-v1-json, actioncable-unsupported
</code></pre>

<p>The connection here is 'upgrade' but the websocket request has the connection 'closed'(probably nginx is messing it up?)</p>

<p>And this piece of code in websocket driver is failing</p>

<pre><code>def self.websocket?(env)
      connection = env['HTTP_CONNECTION'] || ''
      upgrade    = env['HTTP_UPGRADE']    || ''

      env['REQUEST_METHOD'] == 'GET' and
      connection.downcase.split(/ *, */).include?('upgrade') and
      upgrade.downcase == 'websocket'
end
</code></pre>

<p>Updates</p>

<p>This is my nginx configuration</p>

<pre><code>upstream app {
    server unix:/home/osboxes/sites/actioncable-examples/shared/sockets/unicorn.sock fail_timeout=0;
}

server {
    listen 80;
    server_name localhost;

    root /home/osboxes/sites/actioncable-example/public;

    try_files $uri/index.html $uri @app;

    location @app {
        proxy_pass http://app;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_http_version 1.1;
     proxy_set_header Upgrade $http_upgrade;
     proxy_set_header Connection "upgrade";
    }


    error_page 500 502 503 504 /500.html;
    client_max_body_size 4G;
    keepalive_timeout 10;
}
</code></pre>

<p>I have mounted actioncable server on /cable</p>

<pre><code>mount ActionCable.server =&gt; "/cable"
</code></pre>

<p>With the nginx changes i am able to successfully have the handshake but the server is not able to send the heart beats and the connection keeps dropping.</p>

<pre><code>Started GET "/cable" for 127.0.0.1 at 2016-07-07 05:48:06 +0100
Started GET "/cable/" [WebSocket] for 127.0.0.1 at 2016-07-07 05:48:06 +0100
Successfully upgraded to WebSocket (REQUEST_METHOD: GET, HTTP_CONNECTION: upgrade, HTTP_UPGRADE: websocket)
</code></pre>