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Managing infrastructure using Terraform is a modern-day necessity, but as your infrastructure scales, Terraform’s simplicity often gives way to complexity. Code duplication across environments, manual remote state setups, tangled dependencies, and long-winded provisioning workflows can overwhelm even seasoned DevOps engineers. Terragrunt, a lightweight wrapper for Terraform created by Gruntwork, offers a developer-centric solution that tackles these challenges head-on.
This blog dives deep into how Terragrunt improves the way you manage Terraform code. We’ll walk through the core features, real-world use cases, and specific developer benefits it brings, especially when working across multiple environments and large-scale infrastructure setups.
At its core, Terragrunt is not a replacement for Terraform but a supplementary tool that makes Terraform infrastructure as code (IaC) easier to write, reuse, and maintain. It promotes modularity, reusability, and DRY (Don’t Repeat Yourself) principles. It allows developers to keep their configurations clean, scalable, and easy to understand.
In real-world scenarios, Terraform projects can involve tens or hundreds of modules deployed across multiple environments, dev, staging, production, and more. Each environment needs slightly different parameters, but manually duplicating configuration and backend settings across them leads to brittle infrastructure. Terragrunt introduces a structured way to inherit configuration, inject inputs, and define dependencies, all using HCL (HashiCorp Configuration Language), just like Terraform.
For developers, Terragrunt eliminates common friction points in infrastructure provisioning:
Terragrunt acts like a glue layer that keeps Terraform’s modular power intact while drastically reducing its operational burden.
One of the core pain points developers face when working with Terraform is code duplication. Terraform modules need to be explicitly defined and configured per environment. This means that if you have three environments (say dev, stage, and prod), you’ll likely have three nearly identical files, differing only in a few parameters.
With Terragrunt, you can write shared configuration once and use it across environments using include, locals, and the find_in_parent_folders() function. This lets you define providers, remote state configuration, CLI flags, and more just once in a root-level terragrunt.hcl file. All child environments then inherit these settings.
This practice ensures:
For developers working in fast-moving environments, this DRY principle is more than a best practice, it becomes a productivity multiplier.
Remote state management is critical in Terraform-based deployments. When working in teams, it's essential that the state file, which tracks infrastructure status, is stored remotely (e.g., in S3) and locked (e.g., via DynamoDB) to prevent corruption during concurrent operations.
Terragrunt automatically manages these configurations. Instead of copy-pasting backend blocks across every module, you define the remote_state block once in the root terragrunt.hcl. Terragrunt dynamically injects this configuration into all child modules when you run terragrunt apply.
Advantages:
This is especially powerful in CI/CD pipelines, where reproducibility and consistency of remote state handling are non-negotiable.
Terraform does not natively offer a structured way to define dependencies between modules unless you use terraform_remote_state with hardcoded output references.
Terragrunt provides an elegant solution through its dependency block, allowing one module to read outputs from another module without manually configuring data sources.
Example:
dependency "vpc" {
config_path = "../vpc"
}
inputs = {
vpc_id = dependency.vpc.outputs.vpc_id
}
With this, modules are connected programmatically. Terragrunt handles apply order, data flow, and input resolution between modules. It ensures that dependent modules wait until their dependencies are provisioned, all without shell scripts or manual sequencing.
Benefits for developers:
This feature shines in real-world environments where networking, security, databases, and compute layers are all managed separately but interconnected.
If you’ve worked with 10 or more Terraform modules, you know the pain of running terraform plan and apply for each one manually, especially when they have dependencies.
Terragrunt’s run-all command is a game-changer. It allows developers to:
For example:
terragrunt run-all apply
This runs apply across all modules, resolving dependencies automatically. You can selectively target modules, set parallelism, or restrict to a subset.
This kind of orchestration makes large infrastructure changes safer and faster, empowering teams to scale without scripting glue code.
Modern infrastructure management isn’t just about provisioning, it involves pre-checks, validation, custom scripts, notifications, and policy enforcement.
Terragrunt supports hooks that run before or after Terraform commands. Hooks can trigger security scans, code formatters, validation scripts, or Slack notifications. You define them in terragrunt.hcl, and they’re executed automatically.
Example:
terraform {
before_hook "format_code" {
commands = ["apply"]
execute = ["terraform", "fmt"]
}
}
Additionally, you can inherit CLI flags (like -lock=false, -input=false) across modules by defining them once at a parent level.
This feature makes your entire Terraform workflow more automated, more secure, and easier to maintain, crucial in regulated or high-change environments.
A common and effective way to structure your infrastructure with Terragrunt is to separate your modules (pure Terraform logic) from your environment configurations (Terragrunt wrappers).
Example structure:
infrastructure/
├── modules/
│ ├── vpc/
│ ├── rds/
│ └── eks/
└── live/
├── dev/
│ ├── vpc/terragrunt.hcl
│ └── rds/terragrunt.hcl
└── prod/
├── vpc/terragrunt.hcl
└── rds/terragrunt.hcl
At the top of live/, you include a terragrunt.hcl that defines shared logic, like the backend configuration. This keeps all your environments consistent, traceable, and modular.
Each module configuration uses:
The developer workflow remains clean and flexible:
include {
path = find_in_parent_folders()
}
terraform {
source = "../../modules/vpc"
}
inputs = {
cidr_block = "10.0.0.0/16"
}
This gives you the power to version modules, test changes safely, and promote configurations across environments with minimal effort.
By centralizing configuration and reducing repetition, developers spend less time debugging YAML or HCL and more time shipping features. A single change propagates across environments, without introducing bugs.
Using run-all with integrated dependencies means less waiting and fewer manual checks. You get fast, accurate feedback across the entire stack.
No more hand-crafted S3 + DynamoDB blocks. No more forgetting locks. No more broken Terraform state files. Terragrunt takes care of it automatically.
Terragrunt plays well with Atlantis, Jenkins, GitHub Actions, env0, and more. Its CLI-first nature and environment structuring make it ideal for pipelines.
You can test a module in dev, then promote it to stage and prod by simply changing the Git ref in terraform.source. No copy-pasting required. No risky human operations.
Terragrunt transforms how developers manage Terraform infrastructure. It offers a structured, scalable, and developer-friendly approach to handling multiple environments, remote state, dependencies, and orchestration. Whether you're a small team or scaling rapidly, Terragrunt reduces boilerplate, removes friction, and boosts velocity.
If you're tired of repetitive configuration, broken state management, and manual orchestration, give Terragrunt a serious look. It may be the missing link in your Terraform workflow.
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