Use RedisDB with Express-Gateway. How to read DB credentials from .ENV?

I am using a Redis DB to use an Express-Gateway on Heroku. I would like to know how to set Redis credentials as a unique URL-param, instead of using separated vars.

Right now, Express Gateway reads credentials from the file system.config.yml, where credentials structure is

# Core
db:
  redis:
    host: [host]
    port: [port]
    namespace: [namespace]
    password: [password]

Unfortunately, Redis on Heroku automatically sets credentials as a .ENV var, in the form of URL:

REDIS_URL = "redis://h:[psw]@[host]:[port]"

How can I make Express-Gateway reads credentials from .ENV instead of system.config.yml? Or, how can I make system.config.yml reads from .ENV the whole URL?

Even worst, credentials are not permanent, and are changed periodically without alert. So, how can I make Express-Gateway connect to Redis on Heroku?

Thank you

I solved in this way: splitting the Vars before starting the gateway, and set the Env vars.

    /* ==============
    server.js
    ================*/
    const gateway = require('express-gateway');
    const redis = require('redis')
    const session = require('express-session')
    let RedisStore = require('connect-redis')(session)
    require('dotenv').config();
    
    
      var redis_Url = process.env.REDIS_URL; // auto-stetted by the Redis Heroku Plugin
    
      // example: redis://h:p81efd4c7e0ad310d7da303b7bd348d3d0bd9fcebc7aae61c9ba7c94a95a1290d@ec2-54-247-152-80.eu-west-1.compute.amazonaws.com:12799

      var groups = /^redis:\/\/(.+?)\:(.+?)\@(.+?)\:(.+)$/gi.exec(redis_Url); 
      
      process.env.NM   = groups[1];
      process.env.PASW = groups[2];  
      process.env.HOST = groups[3];
      process.env.R_PORT = groups[4]; // !!! don't use PORT as Env var name!!!

    
      // Run the gateway
      gateway()
      .load(path.join(__dirname, 'config'))
      .run();

and

     #==============
     # system.config.yml
     #================
        
        # Core
        db:
          redis: 
            host: ${HOST} 
            port: ${R_PORT} 
            namespace: EG
            password: ${PASW}