Infrastructure as Code (IaC) treats infrastructure—servers, load balancers, databases, networking rules—as software. Instead of clicking through a cloud console or manually configuring hardware, you write the desired infrastructure in a version-controlled text file (JSON, YAML, HCL, or Python), and a provisioning tool (Terraform, CloudFormation, Pulumi, Ansible) reads that file and creates or updates real resources to match it.
IaC works by declaring your desired end-state in code. A provisioning engine compares that declaration against what currently exists, computes the difference, and applies only the necessary API calls to your cloud provider. This makes infrastructure repeatable, auditable, and easy to version—the same file deployed twice produces the same result.
Example: A Terraform file declaring a web server might look like:
resource "aws_instance" "web" {
ami = "ami-0c55b159cbfafe1f0"
instance_type = "t2.micro"
tags = {
Name = "production-server"
}
}
Running terraform apply creates that exact EC2 instance; running it again changes nothing (idempotency).
IaC reduces manual errors, shortens deployment time, and pairs well with health checks and monitoring to catch misconfigurations early. Teams often combine it with automated testing to catch mistakes in the definition file before applying it to production.
WarningConfiguration drift is a real risk: if someone manually changes a resource in the cloud console outside your IaC tool, the tool's recorded state falls out of sync with reality. Regular drift detection and remediation (or a policy to always change infrastructure through code) prevents this.