AWS Atlantis at Scale: How to Streamline Terraform Workflows

As cloud infrastructure becomes increasingly complex, many DevOps teams use AWS with Atlantis to automate Terraform workflows. This open-source tool links Git pull requests to Terraform operations. It helps teams improve Infrastructure as Code practices across different environments. It also helps maintain governance on a large scale.

Terraform is widely adopted for provisioning AWS infrastructure—but as environments grow, teams encounter new layers of complexity:

• Multiple DevOps teams making concurrent changes
• Hundreds of thousands of resources across accounts
• Complex dependencies between modules and services
• Security, IAM, and compliance constraints
• Need for consistent, auditable deployments at scale

Many teams start with Atlantis—but as infrastructure scales, so do the limitations. This post is your deep-dive guide to scaling Terraform on AWS with Atlantis—and making it work in high-scale, multi-team environments.

👉 Want to explore alternative tools beyond Atlantis? Read our comparison blog

What is Atlantis?

Atlantis is an open-source tool that automates the Terraform workflow using pull requests. It bridges your version control system (GitHub, GitLab, or Bitbucket) and Terraform execution and enables collaborative infrastructure development.

How Atlantis Works with Terraform

Atlantis listens for webhook events in your repository hosting service. When a pull request modifies Terraform configuration files, Atlantis automatically:

1. Runs terraform plan on the changed files
2. Post a comment directly on the pull request
3. Provides a mechanism to deliver changes by commenting
4. Lock workspaces to prevent multiple concurrent changes

Here’s a typical diagram of where Atlantis fits within your workflow:

Key Features of Atlantis:

• Pull Request-based Workflow: Atlantis syncs your Git repository and automatically triggers Terraform runs on open or updated pull requests.
• Approval Process: Atlantis integrates support for approval workflow so that teams may audit Terraform plans before deployment to guarantee that modifications are compliant and secure.
• Multi-Tenant Support: It enables multiple Terraform configurations for different environments so that multiple teams are unaffected by each other.
• State Locking: Terraform handles state locking internally to prevent concurrent runs from overriding each other.

To see how Atlantis compares to other Terraform automation tools, check out our in-depth Atlantis alternatives guide.

5 Best Practices for Scaling Terraform with AWS Atlantis

Before diving into Terraform scaling on AWS with Atlantis, you need to understand some basics about the tool. Here are five key points about Atlantis to help you start scaling your Terraform workflow:

1. Use Terraform Workspaces for Multi-Environment

When dealing with large AWS infrastructures, you must split your Infrastructure into multiple environments (e.g., dev, staging, production). Terraform workspaces fit well in Atlantis. You can have multiple state files for different environments. This allows you to keep one large codebase.

Example of Workspace Configuration:

terraform workspace new dev

terraform workspace select dev

terraform apply -var="environment=dev"

2. Custom Workflows for Complex Pipelines

Atlantis’s default workflow (plan → apply) works for simple cases, but complex Infrastructure often requires custom steps:

Custom workflow definition in atlantis.yaml:

3. Handling State Files Securely

Scaling and managing Terraform state becomes critical and Atlantis works best with remote state storage:

terraform {

4. Security and Access Control for Atlantis

Atlantis also facilitates using SSH and IAM roles to secure AWS communications. Atlantis also allows you to lock down who will approve and execute Terraform plans as a security and accountability mechanism. You also can establish AWS IAM roles in Atlantis to communicate with AWS resources securely.

Assuming Different Roles for Different Environments

5. Automating Terraform Plans and Applies

Using Atlantis after you set up Atlantis on your Git repository, the Terraform plan runs automatically. This happens for all updated or opened PRs. Atlantis also has a provision to apply Terraform changes directly once the PR has been approved. This removes the necessity for Terraform to run within the CI/CD pipeline.

AWS Atlantis Challenges When Scaling Terraform

1. Slow Plan and Apply Times

When the Infrastructure grows, Terraform operations begin to slow. Large infrastructures have 5-10-min or longer plans that act as bottlenecks.

Solution: Use Workspace Splitting

Divide monolithic designs into separate, focused work areas:

atlantis.yaml with parallel execution:

2: Managing Permissions Across Multiple AWS Accounts

In the case of multiple AWS accounts, managing permissions becomes complex.

Solution: Use Cross-Account Role Assumption

Create roles in each account that Atlantis can assume

#In your provider configuration

3: Managing Terraform Version Compatibility

As your Infrastructure expands, it becomes challenging to manage Terraform version updates.

Solution: Use Terraform Version Control with Atlantis

4: Sensitive Variable Control

Managing secrets securely with Terraform and Atlantis requires careful consideration.

Solution: AWS Secrets Manager Integration

Create a wrapper script for Terraform that fetches secrets:

Execute terraform with all arguments passed to this script

How Teams Automate Workflows to Scale Terraform Deployments on AWS

Step 1: Implement Repository Structure for Scale

Organize your Terraform code for maximum parallelization and clear ownership:

Step 2: Set Up Advanced Atlantis Configuration

Step 3: Implement Dependency Management

Create a script to manage dependencies between projects:

Step 4: Implement Drift Detection

Create a scheduled task to detect infrastructure drift:

Step 5: Implement Approval Workflows with AWS Services

What If Atlantis with AWS Isn’t Enough?

If your team is managing thousands of Terraform resources, dozens of AWS accounts, or struggling with policy enforcement and visibility—you may have outgrown Atlantis.

While Atlantis is a solid open-source tool for automating Terraform plans and applies through pull requests, it wasn’t designed for enterprise-scale cloud governance. Teams scaling Terraform on AWS often face challenges around:

• Large, complex configurations
• Multi-account IAM permissions
• Policy enforcement and compliance gaps
• ClickOps and infrastructure drift

This is where a platform like ControlMonkey comes in—offering full visibility, automated drift detection, real-time policy enforcement, and Terraform CI/CD that works across cloud and code.

Infrastructure automation should grow with your cloud footprint. If Atlantis is slowing you down, it’s time to explore what’s next.

👉 Book a demo and see how ControlMonkey scales what Atlantis started.

FAQs

How does Atlantis fit into managing Terraform on AWS?

Atlantis helps DevOps teams automate Terraform workflows by triggering plan and apply via pull requests. When used with the AWS provider, it allows teams to apply changes across AWS accounts consistently—without embedding Terraform directly into CI/CD pipelines.

What are the limitations of using Atlantis for Terraform automation on AWS?

Atlantis wasn’t designed for large-scale, multi-account AWS environments. Teams often run into slow plan times, complex IAM role setups, and limited policy enforcement. For advanced use cases, many teams adopt additional tools to handle drift detection, security, and governance at scale.