What is Infrastructure as Code? Explained for beginners

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Bron: artikel integraal overgenomen van FreeCodeCamp
Origineel auteur: Daniel Adentunji

Infrastructure as Code (IaC) is a way of managing your infrastructure like it was code. This gives you all the benefits of using code to create your infrastructure, like version control, faster and safer infrastructure deployments across different environments, and having up to date documentation of your infrastructure.

The article will cover how infrastructure as code works using an analogy. We'll cover the different infrastructure as code tools available as well as declarative vs imperative code

I'll also introduce you to Terraform, which is an open source infrastructure as code tool you can use to create infrastructure across multiple cloud providers like AWS, GCP, Azure and others.

Infrastructure as code in practice

Imagine you are trying to create a three-tiered web application on AWS as you can see in the image below:

The presentation tier is responsible for presenting the user interface to the user. It includes the user interface components such as HTML, CSS, and JavaScript running on EC2 instances.

The logic tier is responsible for processing user requests and generating responses, by communicating with the database layer to retrieve or store data. This is also deployed on EC2 instances

The database tier is responsible for storing and managing the application's data and allows access to its data through the logic tier. The database runs on AWS RDS.

Each of the instances are in an autoscaling group with a load balancer in front of it (except for the database tier).

If you want to create this infrastructure through the AWS console, you would have to manually click through various screens to spin up the infrastructure. This is fine if it is a one time activity.

But if you need to repeat this across different environments like development and test, or need to add additional infrastructure like caches, queues, firewall rules, IAM or SSL certificates, then it becomes increasingly more complex to manage through the AWS console.

Managing complex infrastructure through the console also introduces the possibility of human error.

Infrastructure as code expresses your desired infrastructure in the language of code. This brings all the benefits of code to managing your infrastructure like:

1. Version Control – allows you to store the history of your infrastructure and revert to a previous version if needed.
2. Faster & safer deployments – can recreate infrastructure in new environments quickly and with less errors since every part of the infrastructure is clearly defined in the code.
3. Documentation – your current infrastructure state is documented and kept up to date automatically whenever you make a change. This keeps your infrastructure documentation detailed and accurate, compared to having the infrastructure written in a document or on a confluence page that may not be updated whenever there is a change.

How Infrastructure as Code Works – Explained with an Analogy

Infrastructure as code allows you to create a detailed blueprint of your infrastructure. This blueprint gives instructions to your cloud provider about the infrastructure you want created.

This is similar to how an architecture blueprint works. It outlines the layout, dimensions, materials, and various components of the structure. The blueprint serves as a reference for architects and engineers to understand the desired construction.

The blueprint leaves little room for error. It will be interpreted in the same way by any architect or engineer. If you wanted to build exact copies of this house, all you need is the architecture blueprint.

Infrastructure as code, at a basic level, works in the same way as an architecture blueprint. It details the infrastructure you want to create as code in a number of different possible languages (JSON, YAML, HCL, Python, Ruby, JavaScript, and so on), instructing the cloud provider to create your infrastructure exactly as specified.