Reverse-Proxying Node-RED and Alexa Philips Hue Emulation Bridge

The Alexa Philips Hue Emulation Bridge for node-red provided by the node-red-contrib-amazon-echo package needs to listen on port 80 for HTTP requests sent by Amazon Alexa devices performing discovery. Instructions for the node-red-contrib-amazon-echo package include setting up a port redirect from port 8080 used by the Amazon Echo Hub node in the node-red interface to port 80. Unfortunately, since port 80 is occupied, a webserver performing reverse proxying cannot be placed in front of node-red without some tricks.

One solution is to use nginx and regular expressions in an attempt to match the user-agent of Amazon Echo devices in order to redirect regular HTTP requests to node-red and HTTP requests from Amazon Alexa devices to the node-red-contrib-amazon-echo listening port on 8080:

map "$http_user_agent" $targetupstream {
  default        http://127.0.0.1:1880;
  "~AEO[A-Z]{2,3} Build\/[A-Z0-9]+" http://127.0.0.1:8080;
}

server {
        listen 80;
        server_name mynoderedserver.tld;

        access_log /var/log/nginx/access.log;

        location / {
                proxy_pass $targetupstream;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "upgrade";
        }
}

The map at the top is responsible for conditionally proxying requests based on the user agents: by default, all requests to the server mynoderedserver.tld are passed to node-red on port 1880 and requests that match the regular expression ~AEO[A-Z]{2,3} Build\/[A-Z0-9]+ are delivered to port 8080 on which the Amazon Alexa Philips Hue Emulation bridge (provided by node-red-contrib-amazon-echo') is listening. The result is that a request via a browser to http://mynoderedserver.tld will open up the node-red flow design interface. Similarly, requests to: http://mynoderedserver.tld/ui will open the dashboard provided by node-red-dashboard'' package. This removes the need to memorize ports and/or IP addresses.