Blog - kimserey lam

Blog Posts

Cloudwatch Alarm On Disk Space

Mar 15th, 2019

Few weeks ago we saw how to configure CloudWatch to monitor upstream response time from logs. We create a CloudWatch configuration which allowed us to create metrics by parsing the logs and create a dashboard out of it. Building up from there, today we will see how we can monitor disk used space and trigger an alarm when the remaining disk space is critical.

Cycle Detection With Floyd Tortoise And Hare

Mar 6th, 2019

Floyd’s Tortoise and Hare is a cycle detection algorithm operating on a linked list. The algorithm is based on two pointers, the tortoise and the hare, moving on the linked list at a different speed. The algorithm can be used to find cycle existence, deduces the beginning of the cycle, and the length of a cycle. Today we will explore the mathematical proof behind the algorithm and we will implement it in Racket.

The Basket Of Apples Problem With Tree

Mar 1st, 2019

Working with trees is an interesting task. Today we will look into the Basket of Apples problem, which can be solved using a tree structure. This deep dive will allow us to explore how we can reason around trees and understand concepts allowing us to vocalize ideas.

Fixed Point And Newton Method

Feb 22nd, 2019

Last week, we briefly looked into the Y Combinator also known as fixed-point combinator. Today we will explore more on the territory of fixed-points by looking at what a fixed-point is, and how it can be utilized with the Newton’s Method to define an implementation of a square root procedure.

Recursion With Fibonacci

Feb 14th, 2019

Recursion refers to the property of a function to be defined in term of itself. The Fibonacci sequence is a great example of a recursive problem where a Fibonacci number is calculated from a combination of precedent Fibonacci numbers. Recursion can be implemented in many forms, it is even possible to implement recursion without explicit self calling. Today we will look at different implementations of Fibonacci and discover their properties.

Lambda Calculus And Closure

Feb 6th, 2019

In programming, we often hear about Closures. Closures are present in any languages possessing functions as first class citizen. This includes functional languages and also widespread languages such as C#, Python and JavaScript. Today we will look at the origin of closures and understand what they are.

Implementing Exceptions With Continuations Racket Lisp

Jan 30th, 2019

Last week a colleague of mine introduced me to the concept of continuation in Racket (the best of Scheme and Lisp - at least that is what racket-lang.org states). I knew about the existence of Lisp but I never really paid attention to what it provided as language features. So I took the bite and started to read the post shared to me on continuations, written by Matt Might and oh boy… was I confused. Everything about the code confused me, the notation, the syntax, and of course the flow of the program itself. What I understood was that this piece was implementing Exceptions by using continuations which was enough to make me want to understand it.

Property Based Testing With Hypothesis

Jan 25th, 2019

Property-based testing is a testing method where a property of our system is tested against multiple datasets. Today we will see how we can create property tests using Hypothesis in Python.

Python Web Api With Flask

Jan 18th, 2019

Flask is a microframework for python providing building blocks to compose websites and web API quickly. It has a vast ecosystem driven by open source libraries maintained and used by many developers. Today we will see how we can setup a simple todo web API using Flask and how we can setup OpenAPI 3.0 (OAS3 - previously known as Swagger).

Prometheus With Aspnetcore

Jan 11th, 2019

Prometheus is an open source monitering platform. It provides multiple functionalities to store, manipulate and monitor metrics from our applications. Today we will see how we can push metrics from an ASP NET Core application, and how to make sense of it.

Custom Blue Green Deployment With Nginx And Gitlab Ci

Jan 4th, 2019

Blue-green deployment is a method used to reduce risk and downtime during deployment. Today we will see how we can implement a fully custom Blue-green deployment for a single server setup using Nginx and using Gitlab CI for continuous deployment.

Create A Blog With Jekyll

Dec 28th, 2018

Jekyll is a blog aware static site generator. Blog aware means that it ships with functionalities to build blogs and blog posts. The two major benefits from Jekyll are the markdown translation to HTML and its blog creation orientation. I recently migrated out of blogger and moved to building my own website using Jekyll and today I will share the steps I took.

Vegeta Load Test

Dec 21st, 2018

Load testing helps catch problems which only appear in high load. A common use case of load testing is to load our API with an amount of request of two or three times higher than the usual load. This will provide confidence in our API ability to handle larger traffic. Today we will look into Vegeta, an open source HTTP load testing tool quick and easy to setup. In this post, I’ll demonstrate how quickly and easily we can load test our API endpoints.

Create React App And Mobx

Dec 14th, 2018

I have been using state management frameworks for the past few years, mainly with Angular and NGRX. Today we will see how we can get started with Create-React-App using Mobx as a state management system.

Https With Letsencrypt And Certbot

Dec 7th, 2018

Securing communication between client and server is a mandatory step when building web application. Thanks to Let’s Encrypt, it is now free to setup SSL certificate and with Certbot, the ACME protocol implementation available on Ubuntu, it is a five minutes job to get it to work with Nginx.