Choosing Between Terraform Cloud and Spacelift (and Scalr)

Managing Infrastructure as Code (IaC) effectively is important for modern development teams. While Terraform Cloud provides a foundational service, organizations often seek alternatives like Spacelift and Scalr to address specific needs around flexibility, governance, and operational efficiency.

Core IaC Management Considerations

When evaluating IaC platforms, several core capabilities come into play: state management, policy enforcement, workflow automation, and organizational structure.

State Management Flexibility

• Terraform Cloud: Offers managed remote state storage, which is convenient but locks you into their backend.
• Spacelift: Provides its own managed state backend and also allows using other remote backends.
• Scalr: Delivers maximum flexibility. You can use Scalr's secure, managed state backend or opt for a customer-managed backend (e.g., AWS S3, Azure Blob, Google Cloud Storage). This is particularly beneficial for organizations with existing backend infrastructure or specific data residency requirements.

Policy as Code (PaC) Integration

Effective governance relies on robust Policy as Code.

• Terraform Cloud: Supports Sentinel (proprietary) and Open Policy Agent (OPA), typically as a post-plan check via Run Tasks.
• Spacelift: Features strong OPA integration, allowing policies for various triggers like plan, approval, and push.
• Scalr: Implements OPA natively with pre-plan and post-plan checks. Policies are stored in VCS, enabling a GitOps model for policy changes and impact analysis before enforcement. This proactive approach helps catch issues earlier.

Here's a conceptual example of a Scalr OPA policy (Rego) to enforce tagging:

package scalr.policy.tagging

# Deny if a required tag is missing
deny[sprintf("Resource '%s' is missing the required '%s' tag.", [input.address, required_tag])] {
    # Applies to all manageable resources
    input.type != "data" 
    required_tag := "cost-center"
    not input.values.tags[required_tag]
}

# Deny if the environment tag is incorrect
deny[sprintf("Resource '%s' has incorrect 'environment' tag. Expected '%s', got '%s'.", [input.address, scalr_env_name, actual_env_tag])] {
    input.type != "data"
    actual_env_tag := input.values.tags.environment
    scalr_env_name := scalr.input.environment.name # Access Scalr environment context
    actual_env_tag != scalr_env_name
}

This policy checks for a cost-center tag and ensures the environment tag matches the Scalr environment name.

Workflow Automation and CI/CD

Automating IaC workflows is key to efficiency.

• Terraform Cloud: Integrates with VCS for plan/apply cycles and offers Run Tasks for limited external tool integration.
• Spacelift: Provides a CI/CD-centric approach with customizable runner images and lifecycle hooks.
• Scalr: Supports GitOps workflows and offers custom hooks at multiple stages (pre-init, pre-plan, post-plan, pre-apply, post-apply). This allows for integration of tools like security scanners (e.g., Checkov) or cost estimators directly into the pipeline. Run triggers also enable chaining of workspace runs.

Example of a Scalr pre-plan custom hook (defined in Scalr UI or via its Terraform provider): Command: checkov -d . --framework terraform --quiet --soft-fail This hook runs Checkov before a plan is generated, providing early security feedback.

Organizational Structure and Governance

Scaling IaC requires a clear organizational model.

• Terraform Cloud: Uses Workspaces grouped into Projects.
• Spacelift: Organizes resources into Stacks within Spaces.
• Scalr: Employs a three-tiered hierarchical model: Account > Environment > Workspace. This structure facilitates granular RBAC, and the inheritance of variables, policies, and cloud credentials, simplifying management and ensuring consistency across large organizations.

Pricing Models

• Terraform Cloud: Primarily uses a Resource Under Management (RUM) model, which can lead to unpredictable costs.
• Spacelift: Offers concurrency-based pricing, providing more predictability.
• Scalr: Features a run-based pricing model (e.g., for apply runs), with many operational runs (like drift detection or failed pre-plan policy checks) often being free. This can be highly cost-effective for teams optimizing their run frequency.

Why Scalr Merits Close Consideration

Scalr presents a compelling option for teams prioritizing:

• Backend Choice: Unmatched flexibility in state backend selection.
• Proactive Governance: Deep OPA integration with pre-plan checks and VCS-driven policy management.
• Operational Efficiency: A hierarchical model simplifies management at scale, and custom hooks allow for tailored automation.
• Transparent Cost: Run-based pricing can offer better cost control compared to RUM models.
• OpenTofu Support: Strong, first-class support for OpenTofu alongside Terraform.

Feature	Terraform Cloud	Spacelift	Scalr
Primary IaC Tools	Terraform	Terraform, OpenTofu, Pulumi, CloudFormation, K8s, Ansible	Terraform, OpenTofu, Terragrunt (passthrough)
State Backend	Managed Only	Managed or Other Remote	Managed or Customer-Managed (S3, GCS, Azure, etc.)
Policy as Code	Sentinel, OPA (via Run Tasks)	OPA (Plan, Approval, Push, Trigger, etc.)	OPA (Pre-plan & Post-plan), VCS-driven policies, Checkov
Workflow Customization	Run Tasks	Lifecycle Hooks, Custom Runners	Custom Hooks (multi-stage), Run Triggers
Organizational Model	Workspaces, Projects	Stacks, Spaces	Hierarchical: Account > Environment > Workspace
Pricing Basis	Resources (RUM)	Concurrency	Runs (Applys), many ops free

Conclusion

The choice of an IaC management platform significantly impacts developer productivity and operational stability. While Terraform Cloud and Spacelift offer robust solutions, Scalr distinguishes itself with its flexible state management, proactive and VCS-integrated OPA policies, hierarchical governance model, and potentially more cost-effective run-based pricing. For teams seeking a blend of control, efficiency, and adaptability for their Terraform or OpenTofu workflows, Scalr presents a strong and compelling case.