PORT 3306 Already In use when i rn nodemon in NodeJS app - node.js

Question

I have a nodejs app which was running just fine all this time until I opened MySQL Workbench and also included .env file in my project. I was in the process of deploying the system to Digital Ocean managed database service when I opened MySQL Workbench to visualise the process and not use the mysql shell. Everything worked fine and I migrated my db on to the DO database cluster.
I also wanted to make my app more secure, so I bumped into the .env file method and tried my best to follow through and I came up with this:
Step 1:
npm i dotenv --save
Step 2: Added require('dotenv').config() to my server.js file
Step 3: Update my DB connection file
const mysql = require("mysql");
const conn = mysql.createConnection({
host: process.env.HOST,
user: process.env.USERNAME,
password: process.env.PASSWORD,
//rsport : (process.env.PORT),
database: process.env.DATABASE_NAME,
multipleStatements: true,
});
conn.connect((err) => {
if (err) {
console.log("Oops!, Failed to connect to the database.");
} else {
console.log("Database connection succesfull!");
}
});
module.exports = conn;
Step 4: I set my local .env file and remote .env file accordingly
Step 5: I run nodemon the it return the following error:
body-parser deprecated undefined extended: provide extended option server.js:27:17
events.js:292
throw er; // Unhandled 'error' event
^
Error: listen EADDRINUSE: address already in use :::3306
at Server.setupListenHandle [as _listen2] (net.js:1318:16)
at listenInCluster (net.js:1366:12)
at Server.listen (net.js:1452:7)
at Function.listen (G:\Maxiko Payment System\Systems\Management Apps\Microservices\mx-core\node_modules\express\lib\application.js:618:24)
at Object.<anonymous> (G:\Maxiko Payment System\Systems\Management Apps\Microservices\mx-core\server.js:47:5)
at Module._compile (internal/modules/cjs/loader.js:1063:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
at Module.load (internal/modules/cjs/loader.js:928:32)
at Function.Module._load (internal/modules/cjs/loader.js:769:14)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
Emitted 'error' event on Server instance at:
at emitErrorNT (net.js:1345:8)
at processTicksAndRejections (internal/process/task_queues.js:80:21) {
code: 'EADDRINUSE',
errno: -4091,
syscall: 'listen',
address: '::',
port: 3306
}
[nodemon] app crashed - waiting for file changes before starting...
What am I doing wrong? honestly I do not think .env has anything to do with this, but i definately know MySQL Workbench made its own connection. So am I to believe that only one application can connect to a database at one time? That doesnt sound right to me either.

Answer 1

Try running your node js server on a different port or run this command in command prompt (as administrator)
netstat -ano | findstr :<PORT>
Replace with your port number that is in use(in your case 3306)
Then it will show you the PID of your process
Something like this
TCP 0.0.0.0:3306 0.0.0.0:0 LISTEN 77777
77777 is the PID
then run this command
taskkill /PID <PID> /F
Replace with the PID you got in the last command

Answer 2

Its look like some other process already running on your port 3306
You can check it by using below command
lsof -i tcp:3306
It will list you process that is already on the port 3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
node 12012 user 20u IPv6 86535 0t0 TCP *:3306 (LISTEN)
That shows a process with PID 12012 already using your port 3306
If this process is redundant you can kill it by following command:
sudo kill -9 PID
Replace PID with your process id which in my case is 12012
otherwise you can use some other port to run your node server

Answer 3

I have found the problem. There was indeed another process running and using the same port. In app server initialization script , I was setting the port like this:
app.use('port', process.env.PORT || 5000)
Where at the the fdatabase connection file, I set the ports also as
const conn = mysql.createConnection({
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASS,
port : (process.env.DB_PORT),
database: process.env.DB_NAME,
multipleStatements: true,
});
So, as you can see, there is supposed to be a port conflict since i only had on PORT=3006 variable in the .env file.
SOLUTION
All I had to do was specify the database port as
DB_PORT = 3006
APP_PORT = 5000
in the environment variables.
Thank you and Goog luck.