Changing Websocket url, how to deal with it?

General
1

Hello,

I'm using a websocket that changes it's URL frequently, is it possible to workaround this (for example pass options via a msg to configure the URL?).

Currently I'm using: https://flows.nodered.org/node/node-red-contrib-function-npm and manually implementing ws via 'require', but this isn't flexible as once a websocket connection is opened, I can't seem to close it, even by redeploying the function node (I guess it runs as another process in the background!).

Can anyone suggest a viable workaround?

2

I would begin looking at the source. Websockets exist for interaction and should be available at a single endpoint.

3

Sadly, the endpoint does change (like one of IBM's own Watson endpoints!).

Further, at times I find myself needing to dynamically create endpoint URL's due to changing product options, I was hoping there was a way I could automate endpoint changes...

4

I've located the code for the websocket node here:

I just need to work out how to add an option whereby the url can be set via a msg...

5

Sadly, the endpoint does change (like one of IBM's own Watson endpoints!).

these are static according to their documentation.

6

I ended up solving the URL issue with NGINX, here is my config:

server {
	listen 80;
	
	server_name mqtt.url;

	client_max_body_size 0;

	root /config/www/php/;
	

	location / {
		fastcgi_index ws.php;
		fastcgi_pass 127.0.0.1:9000;
		include /etc/nginx/fastcgi_params;
	}
}

server {
	listen 80;
	listen 443 ssl;
	
	server_name proxy; # could be a full URL in case this is needed

	client_max_body_size 0;

	# all ssl related config moved to ssl.conf (docker)
	include /config/nginx/ssl.conf;

	location / {
		proxy_pass http://localhost/ws.php;
		proxy_set_header   Host "mqtt.url"; # redirect to earlier instance
        proxy_intercept_errors on;
        error_page 301 302 307 = @handle_redirect; # redirect internally
	}

    location @handle_redirect {
		proxy_http_version 1.1;
		proxy_set_header Upgrade "websocket";
		proxy_set_header Connection "upgrade";
        set $saved_redirect_location '$upstream_http_location'; # This will have the new URL
        proxy_pass $saved_redirect_location;
    }
}

The job of determining which URL to redirect to is handled, in this case, by PHP:

<?php
$url = file_get_contents("https://secret/url"); // mine happens to be available elsewhere on the web
$url = str_replace("wss","https",$url); // nginx doesn't really understand wss, so redirect it as https
header("Location: $url"); // issue a 301 redirect
?>

Within the node red, it's as easy as redirecting to the instance of the nginx, as an added benefit I keep the traffic without SSL downstream of NGINX proxy (ws vs wss), as both instances of node red and nginx are running within the same docker network.

red

Cheers,
Gene

7

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