Implementing Policy-as-Code for Financial Guardrails
How to define budget limits, tagging requirements, and approval workflows as executable, version-controlled policies using Open Policy Agent.
Why Policy-as-Code
Manual governance does not scale. When spending spans thousands of services across multiple accounts, policies must be automated, testable, and auditable.
Architecture
Use Open Policy Agent (OPA) as the policy engine. Define policies in Rego that evaluate against resource provisioning requests, budget thresholds, and tagging compliance.
Sample Policies
Start with three foundational policies: mandatory tagging (every resource must have cost-center, owner, and environment tags), budget alerts (trigger notification at 80% and block at 100% of monthly budget), and approval gates (any resource exceeding $500/month requires manager approval).
Deployment Pattern
Deploy OPA as a sidecar to your IaC pipeline. Every Terraform plan or CloudFormation template is evaluated against the policy bundle before execution. Rejected plans generate detailed compliance reports.
Related Articles