Docker Error occured while trying to proxy to: localhost:5000 - node.js

Question

I get the following error when using a express-react app on docker.
i referred to this
React Proxy error: Could not proxy request /api/ from localhost:3000 to http://localhost:8000 (ECONNREFUSED)
and the solution doesn't seem to work.
setupProxy.js
const proxy = require('http-proxy-middleware');
module.exports = function(app) {
app.use(proxy('/auth/github', { target: 'http://[::1]:5000/' }))
app.use(proxy('/api/users/auth/github', { target: 'http://[::1]:5000/' }))
app.use(proxy('/api/users/', { target: 'http://[::1]:5000/', "secure": false }))
app.use(proxy('/api/posts/', { target: 'http://[::1]:5000/' }))
}
Dockerfile
FROM node:8.10.0-alpine
EXPOSE 5000
COPY . /home/app
WORKDIR /home/app
RUN npm install
CMD ["npm", "start"]
docker-compose.yml
# docker-compose.yml
version: "3"
services:
app:
build: .
restart: always
depends_on:
- postgres
ports:
- 5000:3000
postgres:
image: postgres:9.6.8-alpine
expose:
- 5432
environment:
POSTGRES_PASSWORD: postgres
POSTGRES_USER: user
POSTGRES_DB: db
Package.json
{
"name": "sequelize-demo",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"client": "cd ./client && npm start ",
"server": "nodemon app.js --ignore client",
"build": "echo 'hello build'",
"start": "concurrently --kill-others \"npm run server\" \"npm run client\""
},
"author": "",
"license": "ISC",
"dependencies": {
"async": "^2.6.1",
"bcrypt": "^3.0.3",
"body-parser": "^1.18.3",
"concurrently": "^4.1.0",
"cookie-parser": "^1.4.3",
"cookie-session": "^2.0.0-beta.3",
"cors": "^2.8.5",
"crypto": "^1.0.1",
"dotenv": "^6.2.0",
"express": "^4.16.4",
"express-flash": "0.0.2",
"express-session": "^1.15.6",
"jsonwebtoken": "^8.4.0",
"morgan": "^1.9.1",
"nodemailer": "^5.1.1",
"nodemon": "^1.18.9",
"passport": "^0.4.0",
"passport-github": "^1.1.0",
"passport-github2": "^0.1.11",
"passport-jwt": "^4.0.0",
"passport-local": "^1.0.0",
"pg": "^7.8.0",
"pg-hstore": "^2.3.2",
"sequelize": "^4.42.0"
}
}
app.js
var express = require('express');
var app = express();
var userRoute = require('./routes/users');
var postRoute = require('./routes/posts');
var bodyParser = require('body-parser');
var logger = require('morgan');
var models = require('./models');
var User = require('./models/user');
var session = require('express-session');
var cookieParser = require('cookie-parser') ;
var cookieSession = require('cookie-session');
var dotenv = require('dotenv');
var env = dotenv.config();
var cors = require('cors');
const port = process.env.PORT || 5000;
const passport = require('passport');
const path = require('path');
// CORS Middleware
app.use(cors());
app.use(logger('dev'));
app.use(express.static(path.join(__dirname, 'public')));
app.use(cookieParser());
app.use(bodyParser());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(session({
secret : 'nodeauthsecret',
resave: false,
saveUninitialized: true,
}));
app.use(passport.initialize());
app.use(passport.session());
require('./config/passport')(passport);
require('./config/passport-github')(passport);
app.use(function(req, res, next) {
res.locals.user = req.user; // This is the important line
console.log(res.locals.user);
next();
});
// app.use(function(req, res, next) {
// res.setHeader("Access-Control-Allow-Origin", "*");
// res.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
// });
app.use('/api/users', userRoute )
app.use('/api/posts', postRoute )
app.listen(port, function() {
console.log(`Server is running on ${port}`);
});

Answer 1

Let's make sense of this:
The API server listens for requests on default port of 5000 in the docker container.
The API service is composed using docker-compose to publish port 5000 in the node machine for target port 3000 in the container.
Then, the client server is set up to proxy API requests to port 5000 in the node machine.
Clearly, there isn't any service running on 3000 in the container.
You can correct the target port by setting it to 5000 in docker-compose.yaml
ports:
- 5000:5000