Book Image

Scala Microservices

By : Selvam Palanimalai, Jatin Puri
Book Image

Scala Microservices

By: Selvam Palanimalai, Jatin Puri

Overview of this book

<p>In this book we will learn what it takes to build great applications using Microservices, the pitfalls associated with such a design and the techniques to avoid them. </p><p>We learn to build highly performant applications using Play Framework. You will understand the importance of writing code that is asynchronous and nonblocking and how Play leverages this paradigm for higher throughput. The book introduces Reactive Manifesto and uses Lagom Framework to implement the suggested paradigms. Lagom teaches us to: build applications that are scalable and resilient to failures, and solves problems faced with microservices like service gateway, service discovery, communication and so on. Message Passing is used as a means to achieve resilience and CQRS with Event Sourcing helps us in modelling data for highly interactive applications. </p><p>The book also shares effective development processes for large teams by using good version control workflow, continuous integration and deployment strategies. We introduce Docker containers and Kubernetes orchestrator. Finally, we look at end to end deployment of a set of scala microservices in kubernetes with load balancing, service discovery and rolling deployments. </p><p></p>
Table of Contents (12 chapters)

Rolling deployments

Now that our application is fully functional, it's time to test deploying new code updates to simulate active software development cycle.

Let's assume there is a change in product design of the homepage. It will lead to code change to the web-app source code. The product team feels the title of the web-app should be not be Seeker, but New-Seeker.

$ vim chapter-4/web-app/app/assets/javascripts/components/Layout.js

On line 60, I will change the <Header> value from Seeker to New-Seeker. So, when we open the web-service homepage, we should see the change, as shown here:.

$ cd chapter-4/web-app/app/assets/javascripts/
# The homepage code is written in ReactJS and uses Webpack. For more details, checkout chapter4/web-app/Readme.md
$ npm run build
$ sbt "project web-app" dist

Build and push the new docker image with a distinct tag:

$ docker...