wip added express-example followup

Dockerfile

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+FROM node:20
+
+WORKDIR /usr/src/app
+
+COPY ./index.js ./index.js
+
+CMD node index.js
+
+
+# $ docker build -t fs-hello-world . 
+# $ docker run fs-hello-world

express-example/.dockerignore

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+.dockerignore
+.gitignore
+node_modules
+Dockerfile

express-example/.gitignore

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+node_modules
+

express-example/Dockerfile

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+# Use explicit and deterministic Docker base image tags
+
+# Install only production dependencies in the Node.js Docker image
+
+# Optimize Node.js tooling for production
+
+# Don’t run containers as root
+
+# Safely terminate Node.js Docker web applications
+
+# Graceful shutdown for your Node.js web applications
+
+# Find and fix security vulnerabilities in your Node.js docker image
+
+# Use multi-stage builds
+
+# Keeping unnecessary files out of your Node.js Docker images
+
+# Mounting secrets into the Docker build image
+
+FROM node:20
+
+WORKDIR /usr/src/app
+# copy as non root user (more secure)
+COPY --chown=node:node . .
+# clean install, respect package.lock, delete modules each time
+RUN npm ci 
+
+ENV DEBUG=playground:*
+
+USER node
+
+CMD npm start
+
+# docker run -p 3123:3000 express-server
+# The -p flag in the run command will inform Docker that a port from the host machine should be 
+# opened and directed to a port in the container. The format is -p host-port:application-port.

express-example/app.js

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+var createError = require('http-errors');
+var express = require('express');
+var path = require('path');
+var cookieParser = require('cookie-parser');
+var logger = require('morgan');
+
+var indexRouter = require('./routes/index');
+var usersRouter = require('./routes/users');
+
+var app = express();
+
+// view engine setup
+app.set('views', path.join(__dirname, 'views'));
+app.set('view engine', 'jade');
+
+app.use(logger('dev'));
+app.use(express.json());
+app.use(express.urlencoded({ extended: false }));
+app.use(cookieParser());
+app.use(express.static(path.join(__dirname, 'public')));
+
+app.use('/', indexRouter);
+app.use('/users', usersRouter);
+
+// catch 404 and forward to error handler
+app.use(function(req, res, next) {
+  next(createError(404));
+});
+
+// error handler
+app.use(function(err, req, res, next) {
+  // set locals, only providing error in development
+  res.locals.message = err.message;
+  res.locals.error = req.app.get('env') === 'development' ? err : {};
+
+  // render the error page
+  res.status(err.status || 500);
+  res.render('error');
+});
+
+module.exports = app;

express-example/bin/www

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+#!/usr/bin/env node
+
+/**
+ * Module dependencies.
+ */
+
+var app = require('../app');
+var debug = require('debug')('part12-containers-applications-main:server');
+var http = require('http');
+
+/**
+ * Get port from environment and store in Express.
+ */
+
+var port = normalizePort(process.env.PORT || '3000');
+app.set('port', port);
+
+/**
+ * Create HTTP server.
+ */
+
+var server = http.createServer(app);
+
+/**
+ * Listen on provided port, on all network interfaces.
+ */
+
+server.listen(port);
+server.on('error', onError);
+server.on('listening', onListening);
+
+/**
+ * Normalize a port into a number, string, or false.
+ */
+
+function normalizePort(val) {
+  var port = parseInt(val, 10);
+
+  if (isNaN(port)) {
+    // named pipe
+    return val;
+  }
+
+  if (port >= 0) {
+    // port number
+    return port;
+  }
+
+  return false;
+}
+
+/**
+ * Event listener for HTTP server "error" event.
+ */
+
+function onError(error) {
+  if (error.syscall !== 'listen') {
+    throw error;
+  }
+
+  var bind = typeof port === 'string'
+    ? 'Pipe ' + port
+    : 'Port ' + port;
+
+  // handle specific listen errors with friendly messages
+  switch (error.code) {
+    case 'EACCES':
+      console.error(bind + ' requires elevated privileges');
+      process.exit(1);
+      break;
+    case 'EADDRINUSE':
+      console.error(bind + ' is already in use');
+      process.exit(1);
+      break;
+    default:
+      throw error;
+  }
+}
+
+/**
+ * Event listener for HTTP server "listening" event.
+ */
+
+function onListening() {
+  var addr = server.address();
+  var bind = typeof addr === 'string'
+    ? 'pipe ' + addr
+    : 'port ' + addr.port;
+  debug('Listening on ' + bind);
+}