ADR 010: Infrastructure as Code

Status: Accepted | Date: 2025-03-10

Context

All environments must be reproducible from source to minimize drift and security risk. Manual changes and missing version control create deployment failures and vulnerabilities.

Compliance Requirements:

• OWASP IaC Security
• ACSC System Hardening

Decision

Golden Path

1. Git Repository Structure: Single repo per application with environments/{dev,staging,prod} folders matching AWS account names (e.g., app-a-infra repo → app-a-dev, app-a-staging, app-a-prod accounts)
2. State Management: Terraform remote state with locking, separate state per environment
3. CI Pipeline:
   • Validate: Trivy scan + terraform plan/kubectl diff drift check
   • Plan: Show proposed changes on PR
   • Apply: Deploy on tagged release only
4. Versioning: Git tags = semantic versions (x.y.z) deployable to any environment
5. Disaster Recovery: Checkout tag + run just deploy --env=prod with static artifacts from ADR 004

Required Tools & Practices

Infrastructure as Code Workflow:

Consequences

Benefits:

• Reproducible infrastructure deployments with version control
• Automated drift detection and prevention mechanisms
• Reliable disaster recovery through infrastructure as code

Risks if not implemented:

• Configuration drift creating security vulnerabilities
• Failed rollbacks during critical incident recovery
• Inconsistent environments affecting application reliability

References

• ADR 001: Application Isolation
• ADR 002: AWS EKS for Cloud Workloads
• ADR 005: Secrets Management