Infrastructure-as-Code

In an earlier blog post you saw how to use cdk8s with AWS Controllers for Kubernetes (also known as ACK), thanks to the fact that you can import existing Kubernetes Custom Resource Definitions using cdk8s! This made is possible to deploy DynamoDB along with a client application, from using cdk8s and Kubernetes.

But, what if you continue using AWS CDK for AWS infrastructure and harness the power cdk8s (and cdk8s-plus!) to define Kubernetes resources using regular code? Thanks to the native integration between the AWS EKS module and cdk8s, you can have the best of both worlds!

Deploy DynamoDB and a client app using cdk8s along with AWS Controller for Kubernetes

AWS Controllers for Kubernetes (also known as ACK) are built around the Kubernetes extension concepts of Custom Resource and Custom Resource Definitions. You can use ACK to define and use AWS services directly from Kubernetes. This helps you take advantage of managed AWS services for your Kubernetes applications without needing to define resources outside of the cluster.

Build a Wordpress deployment as a cdk8s construct

Constructs are the fundamental building block of cdk8s (Cloud Development Kit for Kubernetes) - an open-source framework (part of CNCF) with which you can define your Kubernetes applications using regular programming languages (instead of yaml). In Getting started with cdk8s, you saw how to use the core cdk8s library.

You can also use the cdk8s-plus library (also covered this a previous blog) to reduce the amount of boilerplate code you need to write. With cdk8s-plus, creating a Kubernetes Deployment, specifying it’s container (and other properties) and exposing it via a Service is three function calls away.

cdk8s (Cloud Development Kit for Kubernetes) is an an open-source framework (part of CNCF) using which you can define your Kubernetes applications with regular programming languages (instead of yaml). Some of the previous blogs on this topic covered the getting started experience and using cdk8s-plus library to further improve upon the core cdk8s library features. We are going to continue and push cdk8s even further. This blog post will demonstrate how you can use Kubernetes Custom Resource Definitions with cdk8s. We will start off with a simple Nginx example and then you will use the combination of Strimzi project CRDs along with Go and cdk8s to define and deploy a Kafka cluster on Kubernetes!

The previous blog post covered how to get started with cdk8s (Cloud Development Kit for Kubernetes), that is an an open-source framework (part of CNCF) using which you can define your Kubernetes applications using regular programming languages (instead of yaml).

You were able to setup a simple nginx Deployment and accessed it via a Service - all this was done using Go, which was then converted to yaml (using cdk8s synth) and submitted to the cluster using kubectl. This was a good start. However, since the core cdk8s library is pretty low-level (for a good reason!) the code involved lot of boilerplate (you can refer to the code here).

Infrastructure as Code (IaC) is a well established paradigm and refers to the standard practice of treating infrastructure (network, disk, storage, databases, message queues etc.) in the same way as application code and applying general software engineering practices including source control versioning, testing and more. For exampple, Terraform and AWS CloudFormation are widely-adopted technologies that use configuration files/templates to represent the infrastructure components.

Infrastructure-IS-Code - A different way of thinking about this

Imagine you have an application that comprises of a Serverless function fronted by an API Gateway along with a NoSQL database as the backend. Instead of defining it in a static way (using JSON, YAML etc.), one can represent these components using standard programming language constructs such as classes, methods, etc. Here is pseudo-code example: