process.env.PORT is undefined (in LinuxCloud environment)

process.env variables are set by the "Environment". Basically, they act as access to your systems environment variables. When trying to access process.env.PORT it'll return undefined if you've not setup that environment variable in the shell that you're trying to run your system.

You can set the environment variable up before you run node app.js with the following.

$ PORT=8080 $ node app.js 

In this case we set the environment variable within the existing shell, then we call node with the app.js file. Environment variables are passed from parent processes into processes they start, if you run those two in sequence, you'll be setting up an environment variable within the current shell, and node will then receive that when it starts up (along side all other environment variables).

To see all environment variables avalible to the existing node process you can run console.log(process.env);.

This will be the same for process.env.IP as well.

Side note: C9 and other similar environments often have a lot of pre-set environment variables. This is why it was available on C9. The same is true for Heroku as well, this is because their system must dictate the port your service should use so that their load balancers / reverse proxies can be pre-configured for that port.

After deploying your node project files, you'll need to make sure any env variables are also transferred.

1. Manually copy-paste env variables

From the original host config to the new host config. Use the dashboards on either end. Simple and secure.

--- or ---

2. Manually transfer .env file from project root

(Not recommended for production environments) Node projects often have a .env file in the root, which is commonly excluded from file transfers (for obvious security reasons). You'd need to make sure the new host also has the identical .env file in root. For production environments, this is usually not desired for security reasons, and it's better to use option #1.

Projects using this method are likely using the dotenv package which detects .env and makes the parameters available to your app. It's mainly for development convenience.

You might have .env file into your root folder which appears above package.json file . to solve that move you .env file to /src folder then problem will be solved enter image description here

Try to use this:

require('dotenv').config(); 

Better solution - in NodeJS 20.6.0 or later We dont need dotenv package.

Here how to use it in typescript.

create a env file like development.env inside the root of your directory of your project for example your project name is 'ocean'

// ocean/development.env DATABASE_CONNECTION_URL='mongodb://127.0.0.1:27017/databasename' PORT=3003 

Now configure it inside package.json script

// ocean/package.json "scripts": { "dev": "tsc && npm run copy-env && node --env-file=dist/development.env dist/app.js", "copy-env": "cp ./src/development.env dist/" }, 

How to access the env variables, don't forgot to add ! symbol at the last of env variable.

// inside async method process.env.PORT! // outside async method process.env.PORT 

Simply up your server

npm run dev 

Use dotenv package

import dotenv from "dotenv"; 

and its config

dotenv.config(); 

it will start reading .env file contents