Infrastructure as Code (Iac): the Complete Beginner’s Guide

Infrastructure is one of the core tenets of a software development process—it is directly responsible for the stable operation of a software application. This infrastructure can range from servers, load balancers, firewalls, and databases all the way to complex container clusters.

Infrastructure considerations are valid beyond production environments, as they spread across the complete development process. They include tools and platforms such as CI/CD platforms, staging environments, and testing tools. These infrastructure considerations increase as the level of complexity of the software product increases. Very quickly, the traditional approach for manually managing infrastructure becomes an unscalable solution to meet the demands of DevOps-based modern rapid software development cycles.

And that’s how Infrastructure as Code (IaC) has become the de facto solution in development today. IaC allows you to meet the growing needs of infrastructure changes in a scalable and trackable manner.

What is infrastructure as code?

Infrastructure as Code or IaC is the process of provisioning and managing infrastructure defined through code, instead of doing so with a manual process.

As infrastructure is defined as code, it allows users to easily edit and distribute configurations while ensuring the desired state of the infrastructure. This means you can create reproducible infrastructure configurations.

Moreover, defining infrastructure as code also:

• Allows infrastructure to be easily integrated into version control mechanisms to create trackable and auditable infrastructure changes.
• Provides the ability to introduce extensive automation for infrastructure management. All these things lead to IaC being integrated into CI/CD pipelines as an integral part of the SDLC.
• Eliminates the need for manual infrastructure provisioning and management. Thus, it allows users to easily manage the inevitable config drift of underlying infrastructure and configurations and keep all the environments within the defined configuration.

Declarative vs imperative Infrastructure as Code

When dealing with IaC tools, there are two major differentiating approaches for writing code. These two approaches are declarative and imperative. Simply put:

• An imperative approach allows users to specify the exact steps to be taken for a change, and the system does not deviate from the specified steps.
• A declarative approach essentially means users only need to define the end requirement, and the specific tool or platform handles the steps to take in order to achieve the defined requirement.

The declarative approach is preferred in most infrastructure management use cases as it offers a greater degree of flexibility when managing infrastructure.

Chef is considered an imperative tool, where Terraform, Pulumi, CloudFormation, ART, Puppet are all declarative. Uniquely, Ansible is mostly declarative with support for imperative commands.

IaC vs IaaS

Importantly, IaC is not a derivative of infrastructure as a service (IaaS). They are two different concepts.

• Infrastructure as a Service is one of the core cloud services: virtualized computing resources—servers, networking infrastructure, storage, etc.—are provided via the cloud service.
• Infrastructure as Code is a tool that can be used to provision and manage infrastructure. It is not limited to only cloud-based resources. In fact, you apply IaC to a wide variety of environments, including on-premises.

When & how to use Infrastructure as Code

IaC may seem unnecessary for simpler, less complex infrastructure requirements, but that isn’t accurate. Any—every—modern software development pipeline should use infrastructure as Code to handle the infrastructure.

Besides, the advantages of IaC far outweigh any implementation and management overheads.

Advantages of IaC

Here are the top benefits of IaC:

• Reducing shadow IT within organizations and allowing timely and efficient infrastructure changes that are done in parallel to application development.
• Integrating directly with CI/CD platforms.
• Enabling version-controlled infrastructure and configuration changes leading to trackable and auditable configurations.
• Easily standardizing infrastructure with reproducible configurations.
• Effectively managing configurating drift and keeping infrastructure and configurations in their desired state.
• Having the ability to easily scale up infrastructure management without increasing CapEx or OpEx. With IaC, you’ll reduce CapEx and OpEx spending overall, as automation eliminates the need for time-consuming manual interactions and reduces incorrect configurations.

When to use IaC

Not sure when to use IaC? The simplest answer is whenever you have to manage any type of infrastructure.

However, it becomes more complex with the exact requirements and tools. Some may require strict infrastructure management, while others may require both infrastructure and configuration management. Then comes platform-specific questions like if the tool has the necessary feature set, security implication, integrations, etc. On top of that, the learning curve comes into play as users prefer a simpler and more straightforward tool than a complex one.

The below table shows a categorization of the tools mentioned above according to their ideal use cases.

One tool may not be sufficient in most scenarios. For instance, Terraform may be excellent for managing infrastructure across multiple cloud environments yet may be limited when in-depth configurations are required. In those kinds of situations, users can utilize a tool such as Ansible to carry out the necessary configurations.

Likewise, users can mix and match any IaC tool and use them in their CI/CD pipelines depending on the exact requirements.

(Learn how to set up your own CI/CD pipeline.)