/node_modules/http-proxy/lib/http-proxy/index.js:120; Error: socket hang up

Question

I'm running expressJS in one of the containers I'm trying to run in docker-compose; When I keep pressing CMD+R to refresh the landing page (Probably 3~4 seconds), it says "Error: socket hang up" and broken. Here is the error

saml-enabled-reverse-proxy_1  | /node_modules/http-proxy/lib/http-proxy/index.js:120
saml-enabled-reverse-proxy_1  |     throw err;
saml-enabled-reverse-proxy_1  |     ^
saml-enabled-reverse-proxy_1  | 
saml-enabled-reverse-proxy_1  | Error: socket hang up
saml-enabled-reverse-proxy_1  |     at connResetException (internal/errors.js:561:14)
saml-enabled-reverse-proxy_1  |     at Socket.socketCloseListener (_http_client.js:380:25)
saml-enabled-reverse-proxy_1  |     at Socket.emit (events.js:214:15)
saml-enabled-reverse-proxy_1  |     at TCP.<anonymous> (net.js:658:12) {
saml-enabled-reverse-proxy_1  |   code: 'ECONNRESET'
saml-enabled-reverse-proxy_1  | }

I've spent more than 30 hours on this but still have no clue on this What can be possibly wrong...???

Here is the source code

var express = require("express");
var session = require('express-session');
var cookieParser = require('cookie-parser');
var httpProxy = require('http-proxy');
var fs = require('fs');
var saml = require('passport-saml');
var passport = require('passport');

// ServiceProvider will be the load balancer.
let serviceProvider = 'http://opengrok_docker:8080';
let entryPoint = null;
let hackMode = false;
if (process.env.MODE=='TEST') {
  entryPoint = 'http://localhost:8080/x'
} else if (process.env.MODE=='STAGE') {
  entryPoint = 'xxx'
} else if (process.env.MODE=='PROD') {
  entryPoint = 'xxx'
}

// SAML config options here
var samlStrategy = new saml.Strategy({
    entryPoint: entryPoint,
    issuer: 'urn:opengrok',
    identifierFormat: null,
    decryptionPvk: privateKey, //.key version
    validateInResponseTo: false,
    disableRequestedAuthnContext: false,
}, function(profile, done) {
    return done(null, profile);
});

// Passport Middleware Block
passport.serializeUser(function(user, done) {
    done(null, user);
});

passport.deserializeUser(function(user, done) {
    done(null, user);
});
passport.use('samlStrategy', samlStrategy);

let app = express();
let apiProxy = httpProxy.createProxyServer();
app.get('/', <<<<<----- REFRESHING THIS PAGE over seconds got me error;
    function(req, res) {
        apiProxy.web(req, res, {target: serviceProvider});
    }
);

app.use(session({secret: 'secret', resave: false, saveUninitialized: true}));
app.use(passport.initialize());
app.use(passport.session());
// Static blocks
app.use('/img', express.static(__dirname + '/img'));
app.use('/fonts', express.static(__dirname + '/fonts'));
app.use('/js', express.static(__dirname + '/js'));
app.use('/css', express.static(__dirname + '/css'));
app.use('/font-awesome', express.static(__dirname + '/font-awesome'));
app.use('/source/default/img', express.static(__dirname + '/source/default/img'));
app.use('/source/default', express.static(__dirname + '/source/default'));
app.use('/source/js', express.static(__dirname + '/source/js'));
app.use('/source/api/v1/suggest/config', express.static(__dirname + '/source/config'))

// Serve the app on port 443
var server = app.listen(443, function () {
    console.log('Listening on port %d', server.address().port)
});

Dockerfilie

FROM node:12.10.0

COPY package.json .

RUN npm install

COPY . .
CMD [ "node", "--max-old-space-size=8192", "--trace_gc", "src/index.js" ]

package.json

{
  "name": "aop-sp",
  "version": "1.0.0",
  "description": "Art of Possible Service Provider",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "xxx",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.19.0",
    "connect-ensure-login": "^0.1.1",
    "cookie-parser": "^1.4.4",
    "express": "^4.17.1",
    "express-session": "^1.16.2",
    "http-proxy": "^1.0.0",
    "passport": "^0.4.0",
    "passport-saml": "^1.1.0"
  },
  "devDependencies": {
    "http-proxy-middleware": "^0.20.0"
  }
}

Answer 1

One problem I see with your code is that a request to / will be proxied but also the whole middleware chain will still be executed for the request. This is probably not what you want and could be the reason for ending the tcp-connection before the proxy request has finished processing.

I recommend using http-proxy-middleware instead of http-proxy when using express as it integrates easily as an express middleware:

 const {createProxyMiddleware} = require('http-proxy-middleware');
 ...
 app.get('/', createProxyMiddleware({ target: serviceProvider}));
 ...