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class CircuitBreaker {
  constructor(request, options = {}) {
    const defaults = {
      failureThreshold: 3,
      successThreshold: 2,
      timeout: 6000
    }
    Object.assign(this, defaults, options, {
      request,
      state: "CLOSED",

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Knex Setup Guide

Create your project directory

Create and initialize your a directory for your Express application.

$ mkdir node-knex-demo
$ cd node-knex-demo
$ npm init

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CREATE TABLE test
(
  id INTEGER,
  parent INTEGER
);


INSERT INTO test (id, parent) VALUES
  (1, NULL),
  (2, 1),

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const pg = require('pg')

// create a config to configure both pooling behavior
// and client options
// note: all config is optional and the environment variables
// will be read if the config is not present
var config = {
  user: '', // env var: PGUSER
  database: '', // env var: PGDATABASE
  password: '', // env var: PGPASSWORD

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How to configure HTTPS with Lets Encrypt, Nginx reverse proxy, Express and Node

1. Have a Node app ready for production.
2. Create an app.js file in your project directory:

const express = require('express');
const path = require('path');
const app = express();

// Allow dotfiles - this is required for verification by Lets Encrypt's certbot

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Intro

This is a basic collection of things I do when setting up a new headless ubuntu machine as a webserver. Following the steps below should give you a reasonable secure server with HTTP/2 support (including ALPN in chrome) and the fast NGINX server. I am happy to add things so leave a comment.

Basics

After creating the server (droplet on DigitalOcean) log in with

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# Note (November 2016):
# This config is rather outdated and left here for historical reasons, please refer to prerender.io for the latest setup information
# Serving static html to Googlebot is now considered bad practice as you should be using the escaped fragment crawling protocol

server {
    listen 80;
    listen [::]:80;
    server_name yourserver.com;

    root /path/to/your/htdocs;

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# Enter this command to create a sudoers override/include file:
# sudo visudo -f /etc/sudoers.d/nginx.overrides

# (Make sure you actually have this in your /etc/sudoers - Run `sudo visudo` to check)
# #includedir /etc/sudoers.d

# This file assumes your deployment user is `deploy`

# Nginx Commands
Cmnd_Alias NGINX_RESTART = /usr/sbin/service nginx restart

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#!/usr/bin/env bash

if [ $EUID -ne 0 ]; then
    echo "You must be root: \"sudo ngxdis\""
    exit 1
fi

# -z str: Returns True if the length of str is equal to zero.
if [ -z "$1" ]; then
    echo "Please choose a site."

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How to setup Let's Encrypt for Nginx on Ubuntu 16.04 (including IPv6, HTTP/2 and A+ SLL rating)

There are two main modes to run the Let's Encrypt client (called Certbot):

• Standalone: replaces the webserver to respond to ACME challenges
• Webroot: needs your webserver to serve challenges from a known folder.

Webroot is better because it doesn't need to replace Nginx (to bind to port 80).

In the following, we're setting up mydomain.com. HTML is served from /var/www/mydomain, and challenges are served from /var/www/letsencrypt.