What is Infrastructure as Code (IaC)? (original) (raw)

Infrastructure as Code (IaC) is a methodology for managing and provisioning computing infrastructure. It relies on machine-readable definition files for configuration, rather than manual physical hardware adjustments or interactive configuration tools. By treating infrastructure setup the same way developers treat application code, teams can automate the deployment of networks, virtual machines, Kubernetes clusters, databases, and load balancers rapidly and reliably. It serves as a component of modern DevOps practices, helping enable organizations to scale with consistency and speed.

How Infrastructure as Code works

IaC works by automating the provisioning process through code, removing the need for manual settings in a cloud console. First, developers define the desired infrastructure specifications in configuration files, which are usually stored in a version control system. An automation tool, such as Terraform, then processes these files and makes the necessary API calls to the cloud provider to create, update, or delete the actual resources. This workflow typically follows a path from code (definition) to version control, through a CI/CD pipeline, and finally to provisioning.

Infrastructure as Code Workflow infographic

Declarative versus imperative

When implementing IaC, teams generally choose between two approaches: declarative and imperative. The primary difference lies in whether you focus on the end result or the steps to get there.

Approach Description Example
Declarative You define what you want the final state to look like. The tool figures out the necessary steps to achieve that state. This is the modern standard for tools like Terraform and Kubernetes. "I want 3 virtual machines with 8GB RAM each."
Imperative You define how to change the infrastructure by listing specific commands or scripts to execute in order. "Run script A to start server 1. Then run script B to configure the network. Then run script C..."

You define what you want the final state to look like. The tool figures out the necessary steps to achieve that state. This is the modern standard for tools like Terraform and Kubernetes.

"I want 3 virtual machines with 8GB RAM each."

You define how to change the infrastructure by listing specific commands or scripts to execute in order.

"Run script A to start server 1. Then run script B to configure the network. Then run script C..."

IaC security and scanning

As infrastructure definitions move into code repositories, security practices must adapt to protect these files. "IaC security" and "IaC scanning" refer to the practice of analyzing configuration files for vulnerabilities before the infrastructure is ever deployed—a concept known as "Shift Left" security. Specialized tools scan the code pipeline to detect misconfigurations, such as Storage buckets left open to the public or unencrypted databases, preventing security risks from reaching the production environment.

Use cases of IaC

Multi-cloud deployments

Enterprises often need to run workloads across different environments. Using a tool like Terraform, a team can use a single configuration workflow to deploy and manage resources across Google Cloud, or other cloud environments, and on-premise data centers simultaneously. This reduces the complexity of learning different proprietary tools for each platform.

Disposable environments

Developers frequently need safe places to test new features. With IaC, a team can spin up a temporary "staging" environment that mirrors production exactly, run their tests, and then destroy the environment immediately afterward. This helps ensure testing accuracy while avoiding the cost of keeping a permanent staging server running 24/7.

Disaster recovery

In the event of a catastrophic regional outage, manual recovery can take days. IaC enables "Disaster Recovery as Code," allowing an organization to rapidly re-provision their entire infrastructure in a different region using their existing code definitions. This can dramatically reduce downtime and ensure business continuity.

Benefits of IaC

Adopting IaC can offer significant advantages for organizations looking to modernize their IT operations.

Speed

Automation allows you to deploy complex environments in minutes rather than days or weeks.

Consistency

Because the same code deploys the same environment every time, IaC eliminates "configuration drift"—where servers become inconsistent due to manual ad-hoc changes.

Cost savings

Teams can easily spin down unused resources when they aren't needed, such as turning off development environments on weekends, which helps manage cloud spend.

Version control

Since infrastructure is defined as code, the entire history of your infrastructure changes is stored in one place. This makes it easier to track who changed what and to roll back to a previous version if something breaks.

Implementing IaC on Google Cloud

Google Cloud provides a comprehensive set of tools to support your Infrastructure as Code journey, from initial design to deployment and ongoing management. A great starting point is the Application Design Center, which allows you to explore, customize, and build upon pre-built reference architectures. This helps you design your application stack based on Google Cloud best practices before you write a single line of code, ensuring your infrastructure is well-architected from the start.

Once you have a design, the Google Cloud open ecosystem makes it easy to implement it as code. The platform treats open-source standards like Terraform as a first-class citizen, not an afterthought. Services like Infrastructure Manager allow you to deploy and manage Google Cloud resources using Terraform directly, while Config Connector lets you manage Google Cloud resources through Kubernetes, helping to bridge the gap between cloud infrastructure and container orchestration.

Cloud Resource Manager

Cloud Resource Manager serves as the service for programmatically managing the Google Cloud resource hierarchy, including organizations, folders, and projects. While many teams use IaC to deploy resources like virtual machines, Cloud Resource Manager allows you to define the project structure itself as code. This helps teams automate the setup of new environments with consistent Identity and Access Management (IAM) policies and organizational constraints, ensuring that governance is baked into the infrastructure from the very beginning.

Automating temporary preview environments

One of the most valuable ways to use IaC is to solve the common developer problem: "It worked on my machine, so why did it break in production?" You can solve this by creating temporary environments.

In this workflow, when a developer opens a pull request (PR), IaC tools automatically spin up a temporary, isolated copy of the app. When the PR is merged, the environment self-destructs.

Step 1: Dynamic naming in Terraform

To make this work, your Terraform code cannot have hard-coded names. You must use variables to create unique resources for every PR.

main.tf (Snippet)

Step 2: The Cloud Build configuration

In your cloudbuild.yaml, you inject the PR number into Terraform using the _PR_NUMBER substitution variable provided by Cloud Build.

cloudbuild.yaml (Snippet)

This workflow shifts IaC from a static maintenance task into a dynamic productivity tool that accelerates the review cycle.

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