NodeJS Development using docker

package.json

{
  "name": "docker_web_app",
  "version": "1.0.0",
  "description": "Node.js on Docker",
  "author": "First Last <first.last@example.com>",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "express": "^4.13.3",
    "nodemon": "^1.8.1"
  }
}

scripts\dev_entrypoint.sh

#!/bin/bash

getent group -i $GID
if [ "$?" -ne "0" ]; then
        echo "Group with the same GID not found, adding group"
        groupadd -r -g $GID $GROUP
fi

id -u $_UID
if [ "$?" -ne "0" ]; then
        echo "User with the same UID not found, adding user"
        useradd -r -g $_UID $USER
fi

_USER=`id -u $_UID -n`

# for some reason isn't working...
su - "$_USER"
whoami

cd /app

npm install
./node_modules/nodemon/bin/nodemon.js --legacy-watch server.js

scripts\development.sh

#!/bin/bash

# http://paislee.io/the-ultimate-nodejs-development-setup-with-docker/
# execute with:
# ./scripts/development.sh .

CONTAINER_NAME=fbarriga_node_dev
IMAGE=node:7.7.1
LOCAL_PORT=8080
CONTAINER_PORT=8080

_UID=`id -u ${USER}`
GID=`id -g ${USER}`
GROUP=`id -g -n ${USER}`

docker stop ${CONTAINER_NAME}
docker rm ${CONTAINER_NAME}

docker run -d -p ${LOCAL_PORT}:${CONTAINER_PORT} \
        --name ${CONTAINER_NAME} \
        -e "USER=${USER}" \
        -e "GROUP=${GROUP}" \
        -e "_UID=${_UID}" \
        -e "GID=${GID}" \
        -e "NODE_ENV=development" \
        -v `pwd`:/app ${IMAGE} \
        /app/scripts/dev_entrypoint.sh

server.js

'use strict';

const express = require('express');

// Constants
const PORT = 8080;

// App
const app = express();
app.get('/', function (req, res) {
  res.send('Hello world\n');
});

app.listen(PORT);
console.log('Running on http://localhost:' + PORT);