Vinh v9n

MongoDB 3.2.x SSL with Letsencrypt

Letsencrypt is an initative which aims to increase the use of encryption for websites. It basically allows people to apply for free certificates provided that they prove the they control the requested domain. We will look at the what is needed to secure your MongoDB installation. For more details on setting up a MongoDB server see MongoDB 3.2.x.

Set the hostname

We sould to set the hostname to match the name of the certificate we are going to optain.

sudo hostname mongo0.example.com

Then update the hostname file to set the server name permanently.

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Managing OpenStack instances with Ansible through an SSH bastion host

I'm be using DreamCompute as my OpenStack provider, but there are dozens to choose from. I assume you already have Ansible and the OpenStack CLI tools installed.

Motivation

With the proliferation of OpenStack public clouds offering free and intro tiers, it's becoming very easy to effectively run a simple application for free or nearly free. Also with the emergence of Ansible, you don't need to learn and deploy complicated tools to do configuration management.

	unless ARGV.size > 0
	puts " Missing executable file argument"
	puts " Usage (in a Dockerfile)"
	puts " RUN crystal run ./path/to/list-deps.cr -- ./bin/executable"
	exit 1
	end

	executable = File.expand_path(ARGV[0])

	unless File.exists?(executable)

	# Should work on all Debian based distros with systemd; tested on Ubuntu 16.04+.
	# This will by default install all plugins; you can customize this behavior on line 6. Selecting too many plugins can cause issues when downloading.
	# Run as root (or sudo before every line) please. Note this is not designed to be run automatically; I recommend executing this line by line.

	apt install curl
	curl https://getcaddy.com \| bash -s personal dns,docker,dyndns,hook.service,http.authz,http.awses,http.awslambda,http.cache,http.cgi,http.cors,http.datadog,http.expires,http.filemanager,http.filter,http.forwardproxy,http.geoip,http.git,http.gopkg,http.grpc,http.hugo,http.ipfilter,http.jekyll,http.jwt,http.locale,http.login,http.mailout,http.minify,http.nobots,http.prometheus,http.proxyprotocol,http.ratelimit,http.realip,http.reauth,http.restic,http.upload,http.webdav,net,tls.dns.auroradns,tls.dns.azure,tls.dns.cloudflare,tls.dns.cloudxns,tls.dns.digitalocean,tls.dns.dnsimple,tls.dns.dnsmadeeasy,tls.dns.dnspod,tls.dns.dyn,tls.

	#!/bin/bash
	# TODO: skip tiny files (so small they couldn't be photos)
	# TODO: make sure sym links and other file system oddities are handled
	# TODO: look at paralellization for perf boost

	#
	# Constants
	#
	CHAR_COUNT=12
	BLOCK_COUNT=6

	/*<?php
	///public class PhpJava { public static void main(String[] args) { System.out.printf("/%s",
	//\u000A\u002F\u002A
	class PhpJava {
	static function main() {
	echo(//\u000A\u002A\u002F
	"Hello World!");
	}}
	//\u000A\u002F\u002A
	PhpJava::main();

	package main

	import (
	"log"
	"syscall"
	"unsafe"
	)

	var (
	kernel32 = syscall.NewLazyDLL("kernel32.dll")

	(ns firstshot.chessknightmove
	(:refer-clojure :exclude [== >= <= > < =])
	(:use clojure.core.logic
	clojure.core.logic.arithmetic))

	(defn knight-moves
	"Returns the available moves for a knight (on a 8x8 grid) given its current position."
	[x y]
	(let [xmax 8 ymax 8]
	(run* [q]

	#!/bin/bash

	# --------------------------------
	# Totally Simple Web Server (TSWS)
	# --------------------------------
	#
	# (c) 2015 Dave Fletcher
	# All Rights Reserved
	#
	# This is free and unencumbered software released into the public domain.