Infrastructure as Code for Regulated Environments: Terraform vs Pulumi vs Crossplane

Infrastructure as Code (IaC) is a compliance accelerator in regulated environments. When every infrastructure change must be reviewed, approved, and auditable, manually provisioning resources through a web console is not just inefficient — it is non-compliant. IaC provides a code-based audit trail, version control, and automated validation that satisfies regulatory requirements.

We have deployed Terraform, Pulumi, and Crossplane in production at banks and fintechs. Each has distinct trade-offs for regulated environments. The choice depends on your team’s programming expertise, compliance requirements, and existing infrastructure.

Who Is This Guide For?

This guide is for infrastructure architects, platform engineers, and compliance leads at financial services firms evaluating IaC tools. If you need to provision and manage cloud infrastructure in a way that satisfies audit and compliance requirements, this is for you.

By the End of This, You’ll Know…

• Why IaC is a compliance accelerator, not just a productivity tool
• How Terraform, Pulumi, and Crossplane differ for regulated environments
• The governance patterns that enforce compliance without blocking development
• How to audit infrastructure changes with IaC tooling

Why IaC in Regulated Environments

Regulated environments require:

• Auditability: Every infrastructure change must be traceable to an individual and approved through a change management process
• Reproducibility: Infrastructure must be reproducible across environments (dev, staging, production)
• Version control: Infrastructure changes must be versioned and reviewed before deployment
• Validation: Infrastructure must be validated against compliance policies before deployment

IaC provides all four by definition:

• Auditability: Git history shows who changed what, when, and why (commit messages)
• Reproducibility: IaC templates produce identical infrastructure across environments
• Version control: Infrastructure code is stored in Git with the same review processes as application code
• Validation: IaC tools support policy-as-code validation before deployment

Without IaC, compliance evidence is a collection of screenshots, manual logs, and configuration exports. With IaC, compliance evidence is a Git repository with full history.

Terraform: The Industry Standard

Terraform by HashiCorp is the most widely adopted IaC tool. It uses a declarative configuration language (HCL) to define infrastructure. Terraform 1.14, current as of April 2026, supports multi-cloud and multi-provider infrastructure.

Architecture:

• State file: Terraform tracks the current state of infrastructure in a state file
• Provider plugins: Cloud providers (AWS, GCP, Azure) are supported through provider plugins
• Plan and apply: Terraform generates a plan before applying changes, showing what will be created, modified, or destroyed

Key capabilities for regulated environments:

• Plan review: Every change generates a plan that can be reviewed before application
• State locking: State file locking prevents concurrent modifications
• Import: Existing infrastructure can be imported into Terraform for management
• Sentinel: Policy-as-code framework for validating Terraform plans before application

Regulatory compliance:

• Audit trail: Git history of Terraform files provides audit evidence
• Plan review: Terraform plan output can be attached to change management tickets
• Policy validation: Sentinel policies enforce compliance before deployment

Pulumi: Programming Languages for Infrastructure

Pulumi uses general-purpose programming languages (TypeScript, Python, Go, C#) to define infrastructure. This provides the full power of programming languages for infrastructure definition.

Architecture:

• State management: Pulumi manages state in a backend (Pulumi Cloud, S3, Azure Blob)
• Language SDKs: Infrastructure is defined using language-native constructs
• Preview: Pulumi generates a preview before applying changes

Key capabilities for regulated environments:

• Language features: Use loops, conditionals, and functions to reduce duplication
• Testing: Infrastructure tests using language-native testing frameworks
• Policy-as-code: CrossGuard provides policy validation before deployment
• Secrets: Built-in secret management for sensitive configuration values

Regulatory compliance:

• Audit trail: Git history of Pulumi code provides audit evidence
• Preview review: Pulumi preview output can be attached to change management tickets
• Policy validation: CrossGuard policies enforce compliance before deployment

Crossplane: Kubernetes-Native Infrastructure

Crossplane extends Kubernetes to manage cloud infrastructure as Kubernetes custom resources. Infrastructure is defined using Kubernetes manifests and managed through Kubernetes controllers.

Architecture:

• Kubernetes-native: Infrastructure is managed through Kubernetes API and kubectl
• Compositions: Reusable infrastructure templates defined as Kubernetes resources
• Providers: Cloud providers (AWS, GCP, Azure) are supported through Crossplane providers

Key capabilities for regulated environments:

• Kubernetes-native: Leverages existing Kubernetes expertise and tooling
• GitOps: Infrastructure is managed through Git with reconciliation by Kubernetes controllers
• Compositions: Reusable templates enforce standardisation
• Claim-based access: Developers request infrastructure through claims, not direct provisioning

Regulatory compliance:

• Audit trail: Kubernetes audit logs and Git history provide audit evidence
• Reconciliation: Kubernetes continuously reconciles actual state with desired state
• Policy validation: OPA/Gatekeeper policies enforce compliance before deployment

Head-to-Head Comparison

Governance Patterns

Change Management Integration

IaC integrates with change management processes:

1. Ticket creation: Engineer creates a change ticket with IaC code changes
2. Code review: Pull request reviewed by peer engineer
3. Policy validation: IaC plan validated against compliance policies
4. Approval: Change approved by release manager
5. Deployment: IaC applied automatically
6. Evidence: Git commit, plan output, and deployment logs attached to ticket

Environment Promotion

Infrastructure changes follow the same promotion pattern as application code:

1. Dev: Engineer tests changes in dev environment
2. Staging: Changes promoted to staging for integration testing
3. Production: Changes promoted to production with approval

Drift Detection

IaC tools detect drift — when actual infrastructure diverges from the IaC definition:

• Terraform: terraform plan shows drift
• Pulumi: pulumi preview shows drift
• Crossplane: Kubernetes reconciliation detects drift

What You Can Actually Use Today

• Terraform Cloud: Managed Terraform with team collaboration, policy validation, and audit logging
• Pulumi Cloud: Managed Pulumi with state management, secrets, and team collaboration
• Crossplane: Open-source, Kubernetes-native infrastructure management
• Terraform Sentinel: Policy-as-code for Terraform (commercial)
• Open Policy Agent: Open-source policy engine for infrastructure validation

FAQ

How do we migrate existing infrastructure to IaC?

Use the import feature: Terraform and Pulumi can import existing infrastructure into IaC management. Start with low-risk resources (storage, networking) before migrating critical resources (databases, payment systems).

Can we use multiple IaC tools together?

Yes, but it adds complexity. Some organisations use Terraform for cloud infrastructure and Crossplane for Kubernetes resources. The key is clear ownership — each resource is managed by exactly one IaC tool.

How do we handle secrets in IaC?

Never store secrets in IaC code. Use secret management tools (HashiCorp Vault, AWS Secrets Manager, Pulumi secrets) to inject secrets at deployment time. IaC tools support secret references that are encrypted in state files.

We help regulated financial institutions design and implement infrastructure as code practices that satisfy compliance requirements while enabling developer productivity. If you are evaluating IaC tools for regulated environments, get in touch.