Terraform Cloud vs Spacelift: Decision Criteria

Managing Infrastructure as Code (IaC) effectively is non-negotiable in modern software development. As your infrastructure scales and your team grows, the platform you choose to orchestrate your IaC workflows, manage state, and enforce governance becomes critical. While Terraform Cloud has been a go-to for many, alternatives like Spacelift and Scalr are offering compelling features and different approaches. This post dives deep into these platforms, helping you understand which might be the best fit for your development needs.

Table of Contents

• IaC Tools: The Foundation of Modern Infrastructure
• Terraform Configuration: Beyond the Basics
• Terraform Cloud Workspaces: Organizing Your Infrastructure
• Spacelift Stacks: Flexible Orchestration Units
• Environment Variables: Secure and Contextual Management
• Drift Detection: Keeping Your State and Reality Aligned
• CD Pipelines: Automating Your IaC Lifecycle
• Terraform Cloud Alternative: Why and What to Consider
• Use Case: Matching Platforms to Scenarios
• Cloud Posse: Real-World IaC Management at Scale

IaC Tools: The Foundation of Modern Infrastructure

Infrastructure as Code (IaC) tools allow us to define and manage infrastructure using code, bringing version control, automation, and repeatability to what was once a manual and error-prone process. Terraform is a dominant player in this space, enabling you to provision and manage resources across numerous cloud providers and on-premises environments using HashiCorp Configuration Language (HCL).

While Terraform itself is powerful, managing its execution, state, and collaboration across a team requires more. This is where IaC management platforms come in:

• Terraform Cloud (TFC): HashiCorp's own managed service, designed to facilitate team collaboration, provide remote state management, and integrate with version control systems (VCS) for GitOps workflows. It includes features like a private module registry and policy enforcement through Sentinel or OPA.
• Spacelift: Positions itself as a sophisticated orchestration platform supporting a wide array of IaC tools beyond just Terraform, including OpenTofu, Pulumi, CloudFormation, Kubernetes, Ansible, and Terragrunt. It emphasizes flexibility, a powerful OPA-based policy engine, and extensive workflow customization.
• Scalr: A Terraform Automation and Collaboration (TACO) platform focused on Terraform and OpenTofu. It highlights a hierarchical configuration model, robust OPA-based policy enforcement, and significant flexibility in choosing your state backend.

Understanding the capabilities of these platforms in managing various IaC tools is the first step. While TFC is Terraform-centric, Spacelift's multi-tool support is a key differentiator for organizations with diverse IaC needs. Scalr carves out a niche by strongly supporting Terraform, OpenTofu, and Terragrunt.

Terraform Configuration: Beyond the Basics

At its heart, Terraform configuration involves writing HCL code to define your desired infrastructure state. This includes defining providers, resources, input variables, and outputs. Effective management of this configuration is crucial for maintainability and scalability.

All three platforms assist in managing Terraform configurations, but with different approaches:

• State Management: The Terraform state file is critical. TFC provides secure remote state storage and locking. Spacelift also offers a managed state backend with enhanced security features, or lets you use your own. Scalr offers unparalleled flexibility, allowing its managed backend or any backend Terraform supports (like S3, Azure Blob, GCS), which is a huge plus for data residency or existing infrastructure.
• Modularity: Reusing code through modules is a Terraform best practice. All platforms support private module registries, allowing teams to share and version their custom modules.
• Variables: Parameterizing configurations with variables is essential. TFC uses variable sets. Spacelift uses "Contexts" and per-stack variables, with unique per-stage exposure options (ro_, wo_ prefixes) for enhanced security. Scalr employs a hierarchical variable system (Account > Environment > Workspace) with inheritance and override capabilities, including a "final" keyword to prevent changes at lower levels.

When considering terraform configuration management, think about how sensitive data is handled, how easily configurations can be reused and standardized, and how state is secured and accessed.

Terraform Cloud Workspaces: Organizing Your Infrastructure

Terraform Cloud uses Workspaces as the fundamental organizational unit. Each workspace encapsulates a specific Terraform configuration, its state file, variables, and its link to a Version Control System (VCS) repository. You might have workspaces for different environments (dev, staging, prod), different applications, or different infrastructure components (e.g., networking, Kubernetes cluster, database).

• Purpose: Workspaces help isolate state, manage access control, and trigger runs based on changes to specific parts of your infrastructure code.
• Grouping: TFC allows grouping workspaces into "Projects," primarily for access control and organizational clarity.
• Best Practices: Common advice includes scoping workspaces by component volatility and separating stateful from stateless resources to limit the potential impact of changes (blast radius).

While TFC Workspaces provide a solid foundation, their structure can sometimes feel rigid for more complex scenarios or when managing inter-dependencies between many infrastructure components.

Spacelift Stacks: Flexible Orchestration Units

Spacelift introduces the concept of Stacks, which are analogous to TFC Workspaces but offer significantly broader functionality and flexibility.

• Multi-IaC Support: A single Spacelift Stack can manage not just Terraform, but also OpenTofu, Pulumi, CloudFormation, Kubernetes manifests, Ansible playbooks, and more. This is a major advantage for teams using a diverse toolset.
• Customization: Stacks allow for greater customization, including the use of private worker pools (even on-premises or air-gapped), custom runner images (Docker images), and administrative stack capabilities for managing Spacelift itself.
• Organizational Structure: Spacelift uses "Spaces" as logical containers for Stacks, Contexts (shared configurations), and Policies. This facilitates Role-Based Access Control (RBAC) and allows for delegating partial administrative rights.
• Dependencies: A powerful feature is Stack Dependencies. You can define a directed acyclic graph (DAG) of your infrastructure components, allowing outputs from one Stack to be used as inputs in another. This automates the orchestration of complex, multi-layered infrastructure.
• Blueprints: Spacelift offers Blueprints (YAML templates) to enable self-service infrastructure. Teams can define standardized templates for common infrastructure patterns, allowing developers to provision resources quickly within established guardrails.

Spacelift Stacks are designed for more dynamic and complex environments, offering a higher degree of control and automation over the entire IaC lifecycle compared to the more traditional TFC Workspaces.

Environment Variables: Secure and Contextual Management

Securely managing environment variables and secrets (API keys, database passwords, etc.) is paramount in any IaC setup. Leaked credentials can lead to catastrophic security breaches.

• Terraform Cloud:
  • Uses "Variable Sets" that can be applied to multiple workspaces.
  • Variables can be marked as "sensitive," which encrypts them at rest and makes them write-only in the UI.
  • Standard Terraform environment variables (e.g., TF_VAR_name) are used to pass values.
• Spacelift:
  • Offers fine-grained control through "Contexts" (reusable collections of environment variables, mounted files, and hooks) and per-Stack environment variables.
  • Variables can be plain text or secret (encrypted at rest and in transit).
  • A standout security feature is per-stage environment variable exposure using ro_ (read-only for plan/init) and wo_ (write-only for apply) prefixes. This limits credential exposure to only the necessary phases of a run, adhering to the principle of least privilege.
• Scalr:
  • Provides multi-scope shell and Terraform variables within a clear hierarchy: Account > Environments > Workspaces.
  • Variables set at higher scopes are inherited by lower scopes and can be overridden unless marked "final."
  • Variables can be marked "sensitive," masking them in the UI, API, and logs.
  • Values can be set in the UI or via .tfvars files (with .tfvars taking precedence unless a UI variable is "final").

Spacelift's per-stage exposure and Scalr's hierarchical model with "final" attributes provide more sophisticated and secure mechanisms for managing environment variables and secrets compared to TFC's approach. These features allow for more precise control over how and when sensitive information is accessible.

Drift Detection: Keeping Your State and Reality Aligned

Drift detection is the process of identifying discrepancies between the desired state of your infrastructure (as defined in your Terraform configuration and state file) and its actual, real-world state. Unmanaged drift can lead to inconsistencies, security vulnerabilities, and unexpected behavior.

• Terraform Cloud:
  • Detects drift by running terraform plan. If the plan shows changes when no code modifications were made, drift has occurred.
  • Remediation is typically manual, involving a terraform apply to bring the infrastructure back in line with the configuration.
  • Automated plan runs can be scheduled via CI/CD to proactively check for drift. Health assessments can also schedule these checks.
• Spacelift:
  • Offers built-in, scheduled drift detection.
  • Crucially, it also provides optional automated remediation. Spacelift can be configured to automatically apply changes to correct detected drift, ensuring infrastructure integrity without manual intervention.
  • Provides visibility into the drift status of resources.
• Scalr:
  • Provides drift detection that can be enabled per environment with a configurable schedule.
  • When drift is detected, workspace owners are notified (e.g., via Slack).
  • Offers three resolution options:
    1. Ignore Drift: Acknowledge but take no action.
    2. Sync State: Run a refresh-only operation to update the Terraform state file to match reality.
    3. Revert Infrastructure: Initiate a plan and apply to roll back the drifted changes to match the configuration.
  • Scalr's approach often anchors to Git as the source of truth, comparing the live environment (via terraform plan -refresh=true) against the committed code.

Spacelift's and Scalr's capabilities for not just detecting but also offering automated or guided remediation for drift provide a significant operational advantage. Scalr's multiple resolution options and per-environment scheduling offer a particularly robust and flexible solution.

CD Pipelines: Automating Your IaC Lifecycle

Continuous Delivery (CD) pipelines are essential for automating the testing and deployment of your infrastructure code. Robust CD pipelines for IaC ensure consistency, speed, and reliability.

• Terraform Cloud:
  • Integrates with VCS (GitHub, GitLab, etc.) to automate Terraform runs (plan/apply) based on commits and pull requests.
  • Supports CLI-driven and API-driven workflows.
  • "Run Tasks" allow limited integration of third-party tools (like security scanners or cost estimators) into the run lifecycle at specific points.
• Spacelift:
  • Is effectively a CI/CD platform specifically designed for IaC. It replaces the need for manually configured CI/CD pipelines for infrastructure with its automated Stacks.
  • Offers native GitOps support, automatic IaC deployments for PRs, and self-service infrastructure provisioning via Blueprints.
  • Provides extensive customization through:
    • Lifecycle Hooks: Inject custom scripts/commands before and after various runner phases (e.g., before_init, after_plan, before_apply, after_apply).
    • Custom Runner Images: Bring your own Docker image to have full control over the execution environment.
• Scalr:
  • Supports GitOps workflows (merge-before-apply, apply-before-merge) and direct CLI execution.
  • Custom Hooks: Allows injecting commands or scripts at various stages (pre-init, pre-plan, post-plan, pre-apply, post-apply). This enables seamless integration of external tools like security scanners (e.g., Checkov before terraform init), linters, cost estimators (e.g., Infracost), or configuration management tools (e.g., Ansible post-apply).
  • Run Triggers: Allows chaining workspace executions. A successful run in one workspace can automatically trigger a run in a dependent workspace.

While TFC provides foundational CI/CD for Terraform, Spacelift and Scalr offer far more advanced and flexible capabilities. Spacelift acts as a comprehensive CI/CD orchestrator for a multitude of IaC tools. Scalr provides deep customization within the Terraform/OpenTofu workflow via its hook system and run triggers. The ability in Spacelift and Scalr to inject custom logic at multiple, granular points in the pipeline is a significant advantage for integrating security, compliance, and cost checks directly into the IaC lifecycle.

For instance, with Spacelift, you might have a .spacelift/config.yml defining:

# Conceptual .spacelift/config.yml
before_init:
  - terraform fmt -check
after_plan:
  - tfsec . --format json > /mnt/workspace/tfsec_results.json 
  # Output then used by a Spacelift Plan Policy

With Scalr, you could configure a pre-plan hook in the UI:

checkov -d. --framework terraform --soft-fail

And a post-plan hook:

infracost breakdown --path . --format json --out-file infracost.json && ./scripts/check_budget.sh infracost.json

These examples show how custom validation, security scanning, and cost analysis can become integral parts of your automated IaC deployment process.

Terraform Cloud Alternative: Why and What to Consider

While Terraform Cloud is a natural starting point for many, several factors might lead you to search for a Terraform Cloud alternative:

• Pricing Model: TFC's Resource Under Management (RUM) pricing can become unpredictable and expensive as your infrastructure grows. Even small, numerous resources contribute to the RUM count.
• IaC Tool Support: TFC is primarily for Terraform. If your organization uses or plans to use other IaC tools like Pulumi, CloudFormation, Ansible, or Kubernetes YAML directly, TFC won't provide a unified management plane.
• Workflow Customization: TFC's run lifecycle is relatively fixed. Teams needing more control to inject custom scripts, security tools, or complex approval workflows at various stages might find TFC restrictive.
• Policy Engine: While TFC supports Sentinel (proprietary) and OPA (typically post-plan), alternatives might offer more flexible or deeply integrated OPA capabilities across more stages of the workflow.
• State Backend Flexibility: TFC mandates using its own state backend. Organizations with existing backend infrastructure or specific data residency/compliance requirements for state files might need more options.
• Advanced Orchestration: Features like complex dependency management between infrastructure components, sophisticated inventory management, or advanced self-service capabilities might be more mature in alternative platforms.

What to Look for in an Alternative:

• Spacelift:
  • Multi-IaC: Its biggest draw if you use more than Terraform.
  • Predictable Pricing: Concurrency-based model.
  • Deep OPA Integration: Policies for login, plan, approval, push, triggers, notifications.
  • Full Workflow Control: Lifecycle hooks, custom runners.
  • Advanced Features: Stack dependencies, Blueprints, inventory management.
• Scalr:
  • Backend Flexibility: Use Scalr's or any Terraform-supported backend.
  • Hierarchical Governance: Account > Environment > Workspace model for sharing and standards.
  • Proactive OPA: Pre-plan and post-plan OPA checks, plus native Checkov.
  • Transparent Pricing: Run-based model (many operational runs are free).
  • Developer Experience: Detailed PR comments, apply-from-PR, global module registry.
  • OpenTofu/Terragrunt Focus: Strong support for these tools.

Choosing an alternative involves weighing these factors against your specific pain points with TFC or your anticipated future needs.

Use Case: Matching Platforms to Scenarios

The ideal IaC management platform depends heavily on your specific use case:

• Small Team, Terraform-Only, Simple Workflows:
  • Terraform Cloud (Free/Standard Tier): Can be a good starting point if RUM costs remain manageable. Its UI is relatively straightforward for basic Terraform operations.
• Large Enterprise, Multi-Cloud, Diverse IaC Tools, Complex Governance:
  • Spacelift: Its multi-IaC support, powerful OPA policy engine for granular control across the entire lifecycle (login, push, plan, approval, trigger), private worker pools (for security/compliance, even air-gapped), and stack dependency management make it suitable for complex, heterogeneous environments with high governance needs.
• Platform Teams, Focus on Terraform/OpenTofu, Need for Standardization and Self-Service with Strong Guardrails:
  • Scalr: Its hierarchical model (Account > Environment > Workspace) is excellent for enforcing standards and sharing configurations (credentials, modules, policies, variables) across many teams/projects. Pre-plan OPA checks and native Checkov ensure governance before plans are even generated. Flexible backend options are a plus for enterprises. Its no-code module deployment can facilitate self-service.
• Cost-Conscious Teams with Optimized Terraform Workflows:
  • Scalr: Its run-based pricing, where many operational runs (drift detection, failed pre-plan policy checks) are free, can be very cost-effective for teams that manage their runs efficiently.
  • Spacelift: Predictable concurrency-based pricing helps in budgeting, avoiding surprises from resource counts.
• Organizations Requiring Full Control Over the Execution Environment:
  • Spacelift: The ability to bring your own runner image (custom Docker image) and deploy private worker pools gives ultimate control, essential for specific compliance regimes or when needing custom tooling not available in standard runners.
• GitOps-Heavy Environments with Complex Interdependencies:
  • Spacelift: Its native GitOps design, PR-based previews, automatic deployment on merge, and particularly its Stack Dependency feature (passing outputs from one stack to another) are ideal for managing intricate, interconnected infrastructure components.
• Teams Needing to Integrate Many Third-Party Tools (Security, Cost, Linting):
  • Spacelift: Lifecycle hooks and custom inputs allow policies to act on data from virtually any third-party tool.
  • Scalr: Custom hooks at pre-init, pre-plan, post-plan, pre-apply, and post-apply stages allow for deep integration of various tools directly into the Terraform/OpenTofu pipeline.

Consider your primary drivers: Is it multi-tool support? Granular policy control? Cost predictability? Backend flexibility? The answers will guide you to the platform that best fits your operational reality.

Cloud Posse: Real-World IaC Management at Scale

Cloud Posse is a DevOps acceleration company renowned for its extensive open-source library of Terraform modules and its comprehensive Atmos framework for managing AWS infrastructure. Their approach emphasizes 100% IaC with Terraform, leveraging battle-tested, reusable components and strong GitOps principles.

Cloud Posse's adoption and integration of Spacelift serve as a significant real-world use case and endorsement. They publicly document using Spacelift as a core part of their GitOps strategy for Terraform, particularly for:

• Managing State at Scale: Addressing challenges with indexing and managing Terraform state across numerous stacks.
• Enabling CI/CD for Infrastructure: Automating the deployment of many interdependent infrastructure components.
• Facilitating Collaboration: Providing a centralized platform for teams to work on shared infrastructure.

Cloud Posse has even developed Terraform components (e.g., spacelift/admin-stack, spacelift/spaces) that integrate with their Atmos tool to automate the setup and management of Spacelift itself. This includes programmatically creating Spacelift Stacks and applying policies. They utilize Spacelift's Rego-based policies for governing run triggers, access controls, and other workflow aspects in complex, multi-account AWS environments.

This deep integration by a respected organization like Cloud Posse demonstrates how a platform like Spacelift can be leveraged to implement sophisticated IaC best practices, such as:

• Modularity: All platforms support private module registries.
• GitOps: All platforms offer VCS integration, but Spacelift's design is particularly GitOps-native.
• Automation: Spacelift and Scalr offer more advanced pipeline customization than TFC.
• Standardization: Enforced via hierarchical configuration (Scalr) or reusable contexts and powerful policies (Spacelift).
• Security: Granular RBAC and secure variable handling are key strengths of Spacelift and Scalr.

While there isn't similar public documentation from Cloud Posse regarding deep integration with Scalr, Scalr's features (OPA support, hierarchical model) align well with the general best practices Cloud Posse advocates. However, based on available information, Spacelift plays a more visibly integrated role in Cloud Posse's reference architecture.

Conclusion: Navigating Your IaC Management Journey

Choosing the right IaC management platform is a pivotal decision. Terraform Cloud offers a solid entry point, but its limitations in pricing, flexibility, and multi-tool support have paved the way for powerful alternatives like Spacelift and Scalr.

• Spacelift shines with its unparalleled multi-IaC orchestration, deep and flexible OPA policy integration across the entire lifecycle, and CI/CD-native design. It's ideal for complex, heterogeneous environments demanding maximum programmatic control and workflow customization.
• Scalr excels with its extreme flexibility in state backend choices, a robust hierarchical model for enterprise-wide governance, proactive pre-plan policy enforcement (including native Checkov), and a transparent run-based pricing model. It's a strong choice for organizations primarily focused on Terraform/OpenTofu that need structured control and operational efficiency.

Your decision should be guided by a clear understanding of your organization's IaC toolset, governance needs, scale, team maturity, and budget. There's no one-size-fits-all answer. The best platform is the one that empowers your team to deliver infrastructure reliably, securely, and efficiently. Leverage free tiers and trials to get hands-on experience before making this crucial commitment to your cloud operations.