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)

Deploy!

The difficult part is done. Deploying kubernetes configuration is a breeze. First and foremost, we need to create a K8s namespace, as shown here:

$ kubectl create namespace "sm-talent-search-engine"

Let's focus on auth-service first. ConfigMaps and Secrets needs to be deployed before the Deployment, as they are used it. We are mounting Secrets and ConfigMaps into our pod. If they don't already exist in the same namespace, the deployment will fail:

$ cd auth-app/
$ kubectl apply -f 10-cmaps.yml -n sm-talent-search-engine
$ kubectl apply -f 10-secrets.yml -n sm-talent-search-engine

The creation is almost instant. You can verify it by visiting the dashboard at http://127.0.0.1:8001. Switch the namespace from default to sm-talent-search-engine first. In the sidebar menu on the left-hand side, click on ConfigMaps.

Then, we will deploy deployment followed by...