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Managing infrastructure at scale is one of the most complex challenges that modern DevOps and platform teams face. The more services, environments, and teams you add, the harder it becomes to ensure consistency, minimize duplication, and deploy reliably. While Terraform has long been the standard for defining infrastructure as code (IaC), it comes with its own limitations, especially when used across large organizations with hundreds of modules and multiple environments. This is where Terragrunt, a thin wrapper for Terraform, becomes a game-changer for developers.
Terragrunt doesn’t replace Terraform. Instead, it enhances Terraform’s capabilities by making your configurations more maintainable, scalable, and secure. In this blog post, we’ll explore how Terragrunt simplifies infrastructure as code at scale, offering developer-friendly workflows, powerful automation features, and clean separation of environments and concerns. We'll dig deep into why it matters, how it works, and why many teams consider Terragrunt a must-have for serious IaC efforts.
As your cloud infrastructure grows, across microservices, accounts, environments, and regions, the complexity of managing IaC with just Terraform increases rapidly. Developers often find themselves copy-pasting the same backend.tf, provider.tf, or variable blocks across hundreds of modules. This not only leads to a violation of the DRY (Don't Repeat Yourself) principle but also creates a maintenance nightmare. A single change in how you define backends or remote state management can require changes across dozens or even hundreds of files.
Even more concerning, developers struggle with state file fragmentation, inconsistent folder structures, accidental overwrites, and complex dependency chains. If you’ve ever run terraform apply in the wrong workspace or accidentally applied dev configuration to production, you know exactly how painful this can be.
For developers building real-world infrastructure, the need is clear: we need more structure, smarter defaults, better isolation, and easier orchestration. Terraform alone doesn’t provide these capabilities out-of-the-box, but Terragrunt does.
One of Terragrunt’s most compelling features is its ability to eliminate configuration duplication across modules. In large Terraform projects, backend configuration, provider blocks, and input variables are often repeated endlessly. This makes updates difficult and introduces risk when configuration drift occurs between environments.
With Terragrunt, you can define common configurations in a root terragrunt.hcl file and reference them across modules using include and locals. This means your dev, staging, and prod environments can share a consistent backend setup, locking strategy, or even variable defaults, while still retaining environment-specific overrides where necessary.
For example, you can define your backend once at the root of your project:
remote_state {
backend = "s3"
config = {
bucket = "my-iac-state"
key = "${path_relative_to_include()}/terraform.tfstate"
region = "us-east-1"
encrypt = true
dynamodb_table = "terraform-locks"
}
}
This removes the need to write and maintain a backend.tf in every module. Developers simply include the parent configuration and focus on what matters: their actual infrastructure logic. This aligns closely with Terraform best practices but automates the boilerplate developers usually dread.
Another pain point in infrastructure-as-code projects is managing the correct application order of modules. Imagine you have a VPC module, followed by a security group, then EC2 instances and finally an RDS database. All of these components are interdependent, but Terraform by default does not handle inter-module dependencies across folders unless you manage them manually.
Terragrunt solves this elegantly using the dependency block. You can declare dependencies explicitly and reference output values from other modules:
dependency "vpc" {
config_path = "../vpc"
}
This means when you run terragrunt apply or terragrunt run-all apply, the tool knows exactly which modules to apply first. Terragrunt parses the dependency graph and ensures that the infrastructure is applied in the correct order. This is particularly powerful for multi-layer stacks where a misordered deployment could break production.
Developers working with multi-tier architectures, network segmentation, or secure IAM flows benefit tremendously from this feature because they no longer need brittle Bash scripts or manual sequencing.
Terraform remote state is essential for team-based collaboration, but configuring it correctly across environments can be a nightmare. A small mistake in the backend config can lead to state overwrites, orphaned resources, or drift that’s hard to detect.
Terragrunt provides automated remote state generation with dynamic expressions such as:
key = "${path_relative_to_include()}/terraform.tfstate"
This ensures that every module has a unique state key based on its directory structure, which prevents collisions and makes state easier to organize and audit. Additionally, the get_aws_account_id() and get_env() functions allow you to parameterize state config so you don’t have to hardcode anything.
This means that whether you’re provisioning a VPC for a sandbox account or deploying a production database, the remote state is automatically namespaced, secured, and isolated, without extra work from the developer.
Another major win with Terragrunt is the clarity it brings to multi-environment setups. In traditional Terraform, developers often rely on workspaces to isolate environments. While functional, workspaces are hidden state, which makes it hard for teams to visually audit or understand what infrastructure lives where.
Terragrunt promotes a folder-based layout for live/dev, live/stage, and live/prod. This makes environment separation explicit and visible to everyone on the team, including those onboarding for the first time. A developer can navigate to live/dev/app/ and know they’re looking at the development version of the app infrastructure.
This structure also maps perfectly to GitOps workflows where different branches or PRs can target different environments cleanly. Combined with directory-based state isolation, the risk of accidental cross-environment changes is significantly reduced.
As infrastructure grows, developers need a way to compose multiple modules into reusable units. Terragrunt introduces terragrunt.stack.hcl to group modules logically, say VPC, ECS, and RDS for a given service, into a single stack. This allows you to define the order, shared variables, and output dependencies all in one place.
By using stacks, teams can scale infrastructure without repeating logic. For example, your dev, stage, and prod environments can share the same stack definition and only differ in variable overrides.
With terragrunt run-all apply, you can deploy an entire application stack across multiple modules with a single command. And thanks to built-in dependency resolution, you don't need to hardcode the order, it’s inferred.
Let’s talk about the real-world advantages Terragrunt brings to engineering teams:
It’s worth reiterating: Terraform workspaces provide a lightweight mechanism for managing different states in a single configuration. But they do not address the broader concerns of environment visibility, configuration duplication, or module dependencies.
Terragrunt, in contrast, encourages teams to think in terms of folders, not just backends. This explicit separation reduces mistakes, supports cleaner Git-based workflows, and scales naturally with organization size. While workspaces are fine for individual use or very small teams, Terragrunt is the better choice for teams managing multi-account, multi-region, multi-environment cloud platforms.
If your team is managing:
Then Terragrunt is absolutely worth adopting. It reduces developer cognitive load, prevents configuration drift, and promotes best practices without being intrusive. In essence, Terragrunt enables scalable, repeatable infrastructure with guardrails.
That said, Terragrunt does introduce a learning curve. Teams unfamiliar with HCL or new to Terraform may find the added abstraction confusing at first. For very small infrastructure footprints or greenfield projects with just a few resources, the overhead may not be justified.
But in any setup where infrastructure is shared, complex, or team-owned, the benefits will outweigh the costs, usually very quickly.
Consider a real-world example for a SaaS application:
live/
├─ dev/
│ ├─ vpc/
│ ├─ rds/
│ ├─ ecs/
│ └─ terragrunt.stack.hcl
├─ stage/
├─ prod/
modules/
└─ vpc/, ecs/, rds/
This kind of setup is CI-friendly, modular, auditable, and easy for developers to reason about. It represents the modern best practice for scaling infrastructure in cloud-native environments.
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