imladenovic

Generating a self signed SSL certificate

Creates a resulting server.crt certificate and server.key private key.

Method one

• $ openssl genrsa -des3 -out server.key.tmp 1024
  • Note: Enter a dummy pass pharse (e.g. 1234) and remember it
• $ openssl rsa -in server.key.tmp -out server.key
  • Enter dummy pass pharse from previous step
• Generate certificate request file (CSR)
• $ openssl req -new -key server.key -out server.csr

imladenovic

Python threaded workers using ThreadPoolExecutor()

A pattern for using concurrent.futures.ThreadPoolExecutor() to execute a series of "worker" functions in parallel, processing a queue of assigned "work".

How it works:

• worker_init() creates:
  • Queues for "work" and "results".
  • A threading.Event() to denote "no more work in queue".
  • A futures.ThreadPoolExecutor().

imladenovic

AWS S3 bucket and IAM policy recipes

• Recipes
  • Anonymous GET access
  • Anonymous GET access - match HTTP referrer
  • Full access for specific IAM user/role
  • GET/PUT/DELETE access to specific path within a bucket
  • Restricted LIST & PUT/DELETE access to specific path within a bucket
  • Full access (and S3 console) for specific IAM users
  • Bucket and object delete deny

imladenovic

System Design Cheatsheet

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

Basic Steps

1. 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?

imladenovic

func within(d time.Duration, f func() bool) bool {
  deadline := http://time.Now ().Add(d)
  for http://time.Now ().Before(deadline) {
    if f() { // 🔥
      return true
    }
  }
  return false
}

imladenovic

package main

import (
	"net/http"
	"database/sql"
	"fmt"
	"log"
	"os"
)

imladenovic

/**
 How to stop long running goroutine
 */
package main

import "fmt"
import "time"

func main() {
	done := make(chan bool)

imladenovic

namespace Orders
{
    public class Company
    {
        public string Id { get; set; }
        public string ExternalId { get; set; }
        public string Name { get; set; }
        public Contact Contact { get; set; }
        public Address Address { get; set; }
        public string Phone { get; set; }