Dont understant why My server Node doesn't work with docker

i m learning docker and try to make a server express. My server work locally but not with a container. Here my files et directory structure.

Directory Structure:

- my_project
  |- app
  |  |- index.js
  |  |- ...
  |
  |- package.json
  |
  |- Dockerfile

package.json:

{
  "name": "bottwitterjeuxconcour",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start" : "node index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.18.2"
  }
}

My Dockerfile:

FROM node:19-alpine3.16

WORKDIR /app

COPY app/ .

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 8080

CMD ["npm", "start"]

my index.js

import express from "express";

const port = 8080;

const app = express();



app.get("/", (req, res, next) => {
       res.send('test serveur node sur docker');
});

app.listen(port, () => {
    console.log(`http://localhost:${port}`);
});

I do the next cmd

docker build -t my-node-app .

docker run -p 8080:3000 my-node-app

And i got no result on localhost:3000 or 8080

when i do a : docker ps

i see my container working:

145c4d30dc78   my-node-app   "docker-entrypoint.s…"   17 seconds ago   Up 15 seconds   8080/tcp, 0.0.0.0:8080->3000/tcp   reverent_goodall

I test if my port 8080 is listen with:

docker exec -it reverent_goodall /bin/sh
netstat -tulpn

and got this:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 :::8080                 :::*                    LISTEN      18/node

I don’t understand what don’t work..

>Solution :

docker run -p 8080:3000 my-node-app binds port 3000 of your container to port 8080 of your host. However, your express app is listening on port 8080 and not on port 3000. Therefore try -p 8080:8080. If you expose the port of your container by using -p, then you might also want to remove the EXPOSE 8080 from your Dockerfile.