What is infrastructure as code (IaC)?

Purpose and motivation of IaC

The main goal of IaC is to automate, standardize and increase the reliability of the infrastructure management process. Manual configuration is error-prone, difficult to replicate and scale, and leads to inconsistencies between environments (e.g., development, test, production). IaC solves these problems by treating infrastructure definition like code, making it possible:

• Automation: The entire infrastructure creation and configuration process can be automated using IaC tools.
• Repeatability: A guarantee that an identical infrastructure will be created every time based on the same code.
• Consistency: Eliminate configuration differences between environments.
• Versioning: The ability to track infrastructure configuration changes in the version control system, revert to previous versions and audit changes.
• Speed and scalability: The ability to quickly create and scale complex infrastructure environments.
• Collaboration: Facilitate collaboration between teams (e.g., development and operations) through a common, code-based definition of infrastructure.

Approaches to IaC: declarative vs imperative

There are two main approaches to defining infrastructure as code:

• Declarative approach: You define the desired end state of the infrastructure (e.g., “I need two web servers and a database with certain parameters”), and the IaC tool takes care of achieving that state itself. Examples of tools: Terraform, AWS CloudFormation, Azure Resource Manager, Pulumi.
• Imperative approach: You define a sequence of specific steps (commands) to follow to configure the infrastructure. Examples of tools: Ansible (often used declaratively, but can work imperatively), Chef, Puppet, shell scripts.

The declarative approach is now more often preferred because of its idempotent nature (repeated use of the same code produces the same result) and easier state management.

IaC tools

There are many tools available on the market to support IaC practice. Among the most popular are:

• Terraform: An open-source tool from HashiCorp that supports multiple cloud providers and services (multi-cloud). It works with a declarative approach.
• AWS CloudFormation, Azure Resource Manager (ARM), Google Cloud Deployment Manager: native IaC tools offered by major public cloud providers (AWS, Azure, GCP).
• Ansible: an open source tool for automating the configuration and management of systems, often also used for infrastructure provisioning.
• Pulumi: a tool that allows you to define infrastructure as code using popular programming languages (e.g. Python, TypeScript, Go).

IaC as a key DevOps practice

Infrastructure as code is one of the fundamental practices supporting DevOps culture and methodology. It enables close collaboration between development and operations teams, automation of deployment processes (CI/CD), and building reliable and scalable application environments in an iterative and efficient manner.

Summary

Infrastructure as Code (IaC) is a modern approach to IT infrastructure management that treats its definition like source code. Through automation, repeatability, versioning and consistency, IaC significantly streamlines provisioning and configuration processes, and is a key component of DevOps practices and the effective use of cloud computing.