Infrastructure as Codeのセキュリティ

Infrastructure as Code (IaC) defines cloud resources in declarative files (Terraform, CloudFormation, Bicep) instead of clicking through consoles. It makes infrastructure repeatable, reviewable, and version-controlled.

That same automation means a single mistake can be deployed everywhere instantly.

IaC enables security at scale:

• Changes go through code review and version history
• Configurations are consistent across environments
• Security policies can be enforced automatically

The goal is to catch insecure config before it ever reaches the cloud.

The most frequent IaC security mistakes include:

• Storage buckets open to the public
• Security groups allowing 0.0.0.0/0 on sensitive ports
• Unencrypted volumes and databases
• Overly broad IAM permissions

This Terraform snippet exposes a database port to the entire internet.

Restrict access to a known private range and enforce encryption by default.

Tools like Checkov, tfsec, and Terrascan scan IaC files for insecure patterns before deployment. Run them in CI so risky templates fail the build automatically.

Policy as Code tools like Open Policy Agent (OPA) and Sentinel let you write rules such as 'no public buckets' that block non-compliant plans automatically, turning security standards into enforceable code.

Terraform state can contain secrets and resource details. Store it in an encrypted, access-controlled backend (such as an encrypted S3 bucket with locking), never in the git repository.

• Encrypt state at rest
• Restrict who can read it
• Enable state locking to prevent corruption

Never put credentials directly in IaC files. Reference a secrets manager or inject values at apply time so secrets never land in version control or state.

Drift happens when someone changes infrastructure manually, diverging from the code. Run drift detection regularly so unauthorized or accidental changes are caught and reconciled.

Build reusable modules with secure defaults: encryption on, public access off, minimal IAM. Teams that consume hardened modules inherit good security without having to be experts.

Test your understanding of IaC security.

You learned how to secure Infrastructure as Code: review changes, scan templates with tools like Checkov, enforce policy as code, protect state files, keep secrets out of templates, and detect drift. Catching misconfiguration in code stops it before it reaches production.