January 14, 2024

What is Infrastructure as Code (IaC)?

Infrastructure Automation

Infrastructure as code (IaC) is the act of writing infrastructure configurations as code so they can be understood, repeated, and enforced with less manual effort. IaC is also a powerful way to convert tribal knowledge into technical knowledge. It’s a far-reaching and essential part of managing infrastructure at scale, with benefits that have expanded to platform engineering, security and compliance, network administration, and so much more. 

In this blog, we’ll explore the definition of infrastructure as code, as well as up-to-date use cases and benefits for organizations today. 

Table of Contents 

What is Infrastructure as Code (IaC)?

Infrastructure as code (IaC) is the practice of describing infrastructure in code — just like software. Infrastructure as code enables organizations to automate tasks and processes that would otherwise be done manually, like managing infrastructure and provisioning resources.

Treating infrastructure as if it were code lets you adopt powerful practices that have been used by software developers for years, and with great success — practices that include version control, peer review, automated testing, release tagging, release promotion, and continuous delivery. 

How Does Infrastructure as Code Work?

Infrastructure as code collects information like configurations, resource dependencies, resource properties, instructions, access, and contains it in a structured fashion where version control can be used to enable review, testing and deployment automation. 

The older methods of infrastructure management — manual processes and documentation, brittle single-purpose scripts, and graphical user interface-based tools — each had their uses in the past. Today, though, with the perpetual need to scale infrastructure, adoption of ephemeral infrastructure, and greater application system complexity, new ways of keeping things under control are needed. 

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Consider resource provisioning and allocation. Where it used to take weeks or months to allocate a server, it can be done in a minute or two using innovative practices like virtualization and self-service cloud infrastructure. But the wide adoption of new tools and techniques has shifted the bottleneck from just allocating servers to configuring them. 

These new challenges require a change to the way IT works, but the primary challenges are the same as they’ve always been: 

  • Identify the requirements, propose a change which satisfies the requirements, and implement it. 
  • Reasonably prove a given change is safe and correct by deploying it to a production like environment and running a sufficient number of tests. 
  • Orchestrate change to a potentially large and complex portion of the infrastructure. 
  • Know at any moment the current state of any part of the infrastructure, especially its health. 
  • Know the history of any configuration, including who proposed it, who approved it, and when it was applied. 
  • Do all the above as quickly, efficiently, reliably and securely as possible. 

To address these challenges at modern scale (both in terms of infrastructure and organization), while keeping up with the needs of the business (not to mention keeping the lights on), you need new methods of collaborating, delivering, and gaining situational awareness. 

Who Uses Infrastructure as Code?

Infrastructure as code isn't limited to a single team — its many benefits have become cross-functional to roles that require a shared language to work together. As concepts like DevOps have expanded into other areas of the business (to their benefit!), organizations have found more ways to put shared code to work in places like compliance and security. 

So, who uses infrastructure as code today? 

Here are just a few examples of the kinds of roles that could put IaC to work, and how they might use it: 


How They Use Infrastructure as Code:

System Administrators / Engineers

Automate server and application provisioning, configuration, and maintenance  

Cloud Administrators / Engineers

Manage and deploy cloud resources 

Network Administrators / Engineers

Define and provision network infrastructure in a repeatable way  

DevOps Engineers

Integrate infrastructure provisioning and configuration into CI/CD pipelines  

Application Developers

Spin up local development environments  

Site Reliability Engineers

Ensure infrastructure reliability and consistency 

Security Engineers

Enforce security best practices and compliance requirements through code-base infrastructure management 

Platform Engineers

Build and maintain scalable self-service platforms for developers and other teams 


To understand why more teams are using infrastructure as code, it’s important to understand the benefits of IaC, and how it’s used to solve specific problems. 

infrastructure as code iac

Why Infrastructure as Code is Important 

There is one core reason why infrastructure as code is so critical: it exchanges tribal knowledge for technical expertise. 

A single group can build, share, and solve problems within an organization — and that’s great! But what happens when that group leaves, changes roles, or disbands? All of that critical shared knowledge is gone — and anyone trying to troubleshoot will run into duplicate work and wasted effort. 

Infrastructure as code provides immutable truth with work that is documented, shared, and clear. It will work for the teams that developed the code and long into the future once that team is gone. Replacing tribal knowledge means that infrastructure as code becomes another technical component of the environment — which offers far reaching benefits, as we will explore. 


Infrastructure as code eliminates the need for separate documentation and provides a single source of truth. Infrastructure as code describes the infrastructure’s configuration, components, and relationships – and when changes have been made to any of those, these changes are reflected in the code. 

This method of self-documentation helps teams stay on top of version control history. It also makes it easier to review previous configurations and better understand the reasoning behind any changes. With meaningful code structure and naming, self-documentation can help break down complex infrastructure into more manageable pieces, which improve readability and understanding. 


Infrastructure as code benefits the continuous integration and continuous delivery (CI/CD) pipeline by enabling consistent integrations and faster deployments. The ability to automate deployments can help you roll out code across infrastructure of any size, with less manual intervention and fewer errors.

Version Control 

Code is portable, reusable, and can be managed with version control. Changes to infrastructure as code are committed to version control, where they can be tested, collaborated on, and approved (merged) by peers. 

Once the change to IaC has been accepted, it can be automatically deployed to thousands of systems just as easily as to a single system. The version control system also provides an audit history. Using a continuous integration/continuous delivery system (see above), these steps can be codified into a continuous delivery pipeline. The result of using infrastructure as code with version control is a workflow that promotes collaboration, dramatically shortens feedback loops, reduces deployment risk, and keeps a continuous history of who did what. 

Auditability and Compliance 

Beyond just scalability, there are reasons that organizations would see the benefit of infrastructure as code in the long run — auditability is a powerful reason. A clear record of infrastructure changes means that time is saved when troubleshooting is required, which is extremely helpful for compliance and auditing purposes. 

Infrastructure as code gives you confidence in your compliance, with the ability to prove compliance to auditors. 

When compliance becomes code, it can be easily enforced and scanned for any issues. If there is a conflict between your system configurations and the desired end state, these issues can be remediated automatically by default. 

When code can be reproduced, testing, debugging, and disaster recovery are also part of the benefits of infrastructure as code. For any organization, no matter how complex, there are going to be risks associated with managing infrastructure across different users, devices, and for different needs. You might not be able to foresee these issues, but you can implement a repeatable way to handle issues that appear. IaC acts as both the fire alarm and a fire extinguisher for situations like these. 

Scale and Agility 

Previous methods of IT management won't work if you're trying to address modern scale and agility requirements. Graphical tools can make it difficult to share pieces of configuration with other teams, do peer review on proposed changes, view historical changes, and roll back to a previous set of configurations. And scripts are equally unsuitable for modern scale and agility. They're brittle, unmaintainable, are sprawled throughout teams and individuals, and are rarely portable between environments. 

Defining your infrastructure as code solves these problems because code is portable, reusable, shareable, testable, and introspectable. And in case we haven't said it clearly enough, manual changes are just terrible — period. 

Day 0, Day 1, and Day 2 Operations 

The entire software development lifecycle benefits from the consistency and repeatability of infrastructure as code. Here’s how: 

  • On Day 0, infrastructure as code helps ensure consistency across the entire rollout, from version control to node classification, before the rollout even begins. 
  • On Day 1, all stages of the deployment can be automated through infrastructure as code to ensure that you’re getting consistent, repeatable results. 
  • On Day 2, your goal should be to have a single codebase that can continue to manage your server environments. In that way, infrastructure as code can support your consistent rollout schedule for updates, changes, and more. 

Different Types of Infrastructure as Code 

There are two different approaches for infrastructure as code: declarative and imperative. Before we provide a brief overview of each, you can also explore this topic in greater detail with our free Puppet on-demand education courses PE101 (Deploy & Discover) and PE201 (Design & Manage). 

Declarative IaC 

Declarative infrastructure as code uses a DSL such as Puppet to define the desired state of your system. It keeps track of the state of your system objects, even the resources that you’ll need, and makes configurations to achieve your desired state. 

Imperative IaC 

Imperative infrastructure as code requires specific (exact) steps in a scripting language that are needed to configure your infrastructure and make changes. This can provide more control over the process but can also add complexity at scale. 

Infrastructure as Code Tools

Infrastructure as code tools can be used to automate the creation, deployment, and management of infrastructure resources. Tasks that can be automated by an infrastructure as code tool include: 

  • Deploying applications 
  • Managing storage 
  • Scaling infrastructure 
  • Disaster recovery 
  • Configuring networks 
  • Creating and provisioning servers 

Puppet is just one example of a platform that provides infrastructure as code provisioning and configuration. Terraform, Ansible, Chef, and Saltstack offer different capabilities to meet your infrastructure goals. Using an infrastructure as code tool like Puppet, you might automate the deployment of applications across end devices or keep servers up to date with security patches. You could create and enforce rules around configuration settings and dependencies to ensure that devices are in line with company policies and standards like CIS, PCI DSS, CMMC, DISA Stigs, and others. 

With a range of infrastructure as code tools, each with their own specialty and capabilities, it's important to consider what your organization needs. How often are you rolling out applications or updates? How many servers do you have, and how many end users are you reaching? 

Infrastructure as Code (IaC) vs. Infrastructure as a Service (IaaS)

Infrastructure as code (IaC) and infrastructure as a service (IaaS) are two different things. The main difference is that IaC turns infrastructure configurations into lines of code so they can be managed automatically. IaaS offers on-demand virtual computing resources via the internet (like servers, networking, and storage). 

You can think of IaC as the set of instructions for provisioning and configuring IT resources and services – just turned into code, so you can automate, repeat, and manage them easily. Examples of IaC include Puppet, Terraform, and Chef

On the other hand, IaaS provides point-in-time configurations. It gives you resources and services you need to run your application code when instantiated, with all the necessary configurations built in. Examples of IaaS include Amazon AWS, Microsoft Azure, and Google Cloud Platform. 

Using Infrastructure as Code: Factors to Consider 

If you're not currently using infrastructure as code, you'll want to ask yourself: 

  • How important is security to your org? Infrastructure as code can provide a clear record of all changes made within your infrastructure — ultimately helping to identify and mitigate security risks. 
  • How complicated is your current infrastructure? Infrastructure as code can help wrangle all different components by tracking and managing everything in one place. 
  • How often does your infrastructure change? Automating provisioning and configuration is a great way to save time and effort, especially if you change infrastructure frequently. 
  • Who will be managing your infrastructure? No matter how your teams are structured, the common language around infrastructure as code can encourage collaboration. 

Why Your IaC Language Matters

Depending on the IaC tools you choose, you can write infrastructure as code in a number of languages, including Python, Go, JavaScript, JSON, and YAML. Some IaC solutions use their own unique coding language, like Terraform’s Hashicorp Configuration Language (HCL) and Puppet’s Declarative State Language (DSL), which is based in Ruby. To align everyone in IT, it’s important to establish a common language for everyone to use when contributing to and managing infrastructure. 

With a common language, everyone can propose infrastructure improvements, collaborate on infrastructure implementations, and read the code itself to understand how any part of the infrastructure is being managed. (You may have seen the term "executable documentation" for infrastructure code. That's because the code itself enforces the documented infrastructure policies.)

When choosing your infrastructure code language, there are important factors you should consider. Since you want everyone aligning with a common language, the language needs to have a low learning curve, be declarative, be idempotent, and holistically manage the infrastructure as a single source of truth. Let’s break that down. 

1. Easy Adoption 

It’s important to consider the strengths and skill levels of everyone who contributes to the infrastructure. Are they all software developers with degrees in computer science? Probably not. At the same time, do not underestimate their capabilities, nor their experience in writing some form of code. Ask your DBA to show you their PL/SQL queries — that should convince you your DBA really does know how to write code. Or ask to see your Windows administrator’s batch files or login scripts. Almost anyone in IT can pick up an infrastructure language, provided it is well-designed, purpose-built, and comes with a prescription for how it should be used. 

2. Idempotence 

Idempotence is defined as the property of an action always having the same result. An example in mathematics is taking the absolute value of a number and continuing to apply the absolute value to the result. No matter how many times you perform that operation, the result is always the same. 

An example of idempotence in IT is the rm -f command from Unix. No matter the beginning state, the result is always the removal of the target. 

Idempotency is a critical component to successfully using infrastructure as code. The more your code is idempotent, the more it can handle any condition, and always do the correct thing. 

3. Holistic Modeling 

As more and more of your IT team contributes to the infrastructure code, you need to know your IaC tools can scale to potentially hundreds of contributors across a plethora of teams. Where are all the different places the infrastructure code can live? How many different pieces of code manage the same system? What happens when two contributors write code that manages the same configuration differently? 

With holistic modeling, all the infrastructure code is combined to a single central source of truth that identifies how each piece of infrastructure code relates to every other piece. Because the relationships between all the pieces of code are understood, common mistakes are caught (such as two contributors trying to manage the same configuration differently), and problems are averted. 

Get Started with Puppet's Infrastructure as Code 

Puppet was born from the combination of software development and operations, with infrastructure as code is at the center of it all. With infrastructure as code, Puppet allows you to scale your infrastructure automation with your organization's IT needs, meaning you can do more provisioning, deliver apps faster, stay in compliance, and build more resilient infrastructure with code – and get the same result every time. Infrastructure as code can ultimately make your organization more responsive, collaborative, faster, and more innovative. Puppet can help you reach your goals using infrastructure as code for your specific organizational needs. Even better, you can see how Puppet works within your infrastructure with a free trial: 


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This blog was originally published on February 9, 2017, and has since been updated for accuracy and relevance.