Showing posts from June, 2018

Scala Monads 101

What is a monad ? It's easy to read lots of sites and still don't get the idea. Many people already used monads but few really understand them truly. Monads are a kind of a Myth in Scala for lots of developers. ItÅ› possible to code without creating your own monads? Yes for sure it is. It's very likely you already create abstractions which were similar to monads but with different names. Here are some samples of Monads in Scala: Try , Either and Option . We have some of this monads in Java 8 as well like Optional . Monads come from the Category Theory which is a branch from Math. Monads are very strong concepts in Haskell Language for instance. IMHO one of the reasons why use Monads rather than your uncle abstraction is that they are universal and in theory, they are easier to understand, in practice if you don't study math, Category Theory and Functional Programming principles actually monads will sound much harder than you user uncle abstractions. So, in other word

Experiences Building & Running a Stress Test / Chaos Platform

Stress Test is something that everyone should be doing if you care about performance. I run software at AWS so is easy to spin up more boxes but is also more expensive and you might be in a trap because you might have ineffective software with Memory Leaks, Hidden Bugs, and untuned servers which will all show up with scale or stress tests - whatever happens first. Unfortunately, this still not quite popular among most of the microservices developers. Create and run stress tests is something hard and tedious because it involves lots of moving parts. A single microservice could call several other microservices some of the downstream dependency graphs could get complex easily, this is just one of the many challenges involved with stress tests. Today I want to share some experiences in building and running a stress test and chaos platform. Do you know how many concurrent users or requests per second(RPS) your microservices can handle? Do you know what it will be the COST to scale your se

github-fecther: Checking new Repos from Github with Go

Go lang is a very interesting language. Github already is the central hub for the open source on the Internet. Companys have lots of repositories and it's very hard to catch up nowadays. So I build a simple silly tool in Go in order to fetch all repositories a company might have and they compare with the previous fetch and see if there are new repositories.  Thanks to GO elegance I was able to do that with less than 200 lines of code. In order to do what we need to do, we will use some basic functionality in Go such as IO, Http Calls, JSON support for Structs, Slices, Maps, Error Handling(Which is the sucking part) and a bit of logic. This program can fail since I'm not using a proper TOKEN for github so you will HIT the github Throttling limits pretty quickly if you keep running the program. You can create a proper DEV account and fix the code to use your token or you can schedule the program to run in different times in your crontab. This is not production ready, but it&#

Running Gorilla/Mux in Docker

Go is a very simple and powerful language. I like Go.Go performance is amazing. I don't like that Go don't have proper Generics and Exceptions but besides that is all great. Go is great for DevOps because go generate a simple binary that is executable and this is really awesome. Today I want to show to build a simple counter service using Go, Gorilla/Mux and Docker. Gorilla/Mux is a simple HTTP Router for Go. Using native JSON support from Go + Mux you can build some simple and yet powerful services. We will use sync/atomic in order to make sure if we have a code that is threadsafe.  You will need to have Go and Docker installed in your machine.  We will use Go language version 1.10 and latest Gorilla/Mux. Let's get started! The Dockerfile Here we are using Go 1.10 docker image as the image. We are using to get in order to install gorilla/mux. Now we can build the docker image. We just need to run the command: $  docker run diegopacheco/go-counter . Go Code

Running Ansible with Docker

Ansible is a great provisioning tool. However, it can be painful to get some ansible scripts right. Especially if you need some stuff with bash and Ansible. Often baking time in AWS can be pretty high. So It's better you can run ansible locally. However, running ansible local could mess up with your OS. So the best thing is run ansible in Docker. Since the docker container will be ephemeral, once you finish running the container all changes will be lost. You also will benefit from running locally and being able to figure it out quickly whats wrong.  So today I want to share about some simple project I create in order to help to do that. This is called Ansible-Docker this is an ansible sandbox using Amazon Linux.

Mocking Terraform AWS using Docker

Terraform is a good tool for infrastructure provisioning.  However to test terraform it could be pretty difficult. So you will create some terraform scripts and upload to the cloud a run some slow Jenkins job? and if your syntax is wrong? Well, this process can be very painful. So I want to share some simple sandbox I built in order to speed up terraform + aws development in your local machine. I might be wondering how is that possible─? Well, my secret sauce is Localstack . So we are limited to all endpoints that localstack mocks. As Localsttack adds more endpoints we benefit from that. The main idea behind this simple project is to show how easy is to docker-ize somDevOpsps tools and make engineering easy.  Currently is very often to spend 40mim or more doing baking and that's is wrong. So that's kind of mainframe era so the idea is to save time and run things local - as much as possible. Docker helps a lot with that. I run software in production using AWS Amazon Linux. No