Roman Kiselenko roman-kiselenko

INTRO

Concurrency is a domain I have wanted to explore for a long time because the locks and the race conditions have always intimidated me. I recall somebody suggesting concurrency patterns in golang because they said "you share the data and not the variables".

Amused by that, I searched for "concurrency in golang" and bumped into this awesome slide by Rob Pike: https://talks.golang.org/2012/waza.slide#1 which does a great job of explaining channels, concurrency patterns and a mini-architecture of load-balancer (also explains the above one-liner).

Let's dig in:

Goroutines

Running NGINX and CertBot Containers on the Same Host

The Problem

A lot of people run into the problem of running Let's Encrypt's CertBot Tool and an NGINX on the same container host. A big part of this has to do with CertBot needing either port 80 or 443 open for the tool to work as intended. This tends to conflict with NGINX as most people usually use port 80 (HTTP) or 443 (HTTPS) for their reverse proxy. Section 1 outlines how to configure NGINX to get this to work, and Section 2 is the Docker command to run CertBot.

1. NGINX Configuration

I use Docker Compose (docker-compose) for my NGINX server. My docker-compose.yml file looks something like this:

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	/* eslint-disable no-console */
	import _ from 'underscore';

	/*
	Drop this mixin into a component that wastes time according to Perf.getWastedTime() to find
	out what state/props should be preserved. Once it says "Update avoidable!" for {state, props},
	you should be able to drop in React.addons.PureRenderMixin

	React.createClass {
	mixins: [WhyDidYouUpdateMixin]

	require "diffbench"
	require 'perftools'
	require "bundler"
	Bundler.require
	$:.unshift "../railties/lib"
	$:.unshift "../activesupport/lib"
	$:.unshift "../activemodel/lib"
	$:.unshift "../activerecord/lib"
	require "active_record"
	require 'rails'

	package main

	import (
	"bytes"
	"compress/gzip"
	"database/sql/driver"
	"errors"
	"fmt"
	"github.com/jmoiron/sqlx"
	_ "github.com/mattn/go-sqlite3"

	# /etc/nginx/sites-available/app

	upstream app_server {
	server unix:/tmp/.unicorn_app.sock fail_timeout=0;
	}

	server {
	listen 80;
	server_name app.com;

	# Raw transaction API example work-through
	# Send coins to a 2-of-3 multisig, then spend them.
	#
	# For this example, I'm using these three keypairs (public/private)
	# 0491bba2510912a5bd37da1fb5b1673010e43d2c6d812c514e91bfa9f2eb129e1c183329db55bd868e209aac2fbc02cb33d98fe74bf23f0c235d6126b1d8334f86 / 5JaTXbAUmfPYZFRwrYaALK48fN6sFJp4rHqq2QSXs8ucfpE4yQU
	# 04865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac09ef122b1a986818a7cb624532f062c1d1f8722084861c5c3291ccffef4ec6874 / 5Jb7fCeh1Wtm4yBBg3q3XbT6B525i17kVhy3vMC9AqfR6FH2qGk
	# 048d2455d2403e08708fc1f556002f1b6cd83f992d085097f9974ab08a28838f07896fbab08f39495e15fa6fad6edbfb1e754e35fa1c7844c41f322a1863d46213 / 5JFjmGo5Fww9p8gvx48qBYDJNAzR9pmH5S389axMtDyPT8ddqmw

	# First: combine the three keys into a multisig address:
	./bitcoind createmultisig 2 '["0491bba2510912a5bd37da1fb5b1673010e43d2c6d812c514e91bfa9f2eb129e1c183329db55bd868e209aac2fbc02cb33d98fe74bf23f0c235d6126b1d8334f86","04865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac09ef122b1a9

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

	module Devise
	module Strategies
	class RemoteAuthenticatable < Authenticatable
	#
	# For an example check : https://github.com/plataformatec/devise/blob/master/lib/devise/strategies/database_authenticatable.rb
	#
	# Method called by warden to authenticate a resource.
	#
	def authenticate!
	#