What is Infrastructure as Code (IaC)?

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.

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.

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.

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 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.

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.

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)

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.