Terragrunt

Terragrunt
Name	Terragrunt
Developer	Gruntwork
Initial release	2016
Stable release	0.XX.X
Written in	Go
Repository	GitHub
License	MIT

Terragrunt is an open-source wrapper for Terraform designed to provide tooling for managing infrastructure as code at scale. It aims to simplify the use of Terraform across large organizations by adding abstractions for remote state management, dependency orchestration, and DRY (Don't Repeat Yourself) configuration. Terragrunt integrates with a range of cloud providers and orchestration systems to coordinate infrastructure deployments across multiple modules and environments.

Overview

Terragrunt was created to address limitations encountered by teams using Terraform when managing multi-environment, multi-module infrastructures across organizations such as Amazon Web Services, Google Cloud Platform, Microsoft Azure, HashiCorp, and enterprises following DevOps practices inspired by The Phoenix Project and guides from CNCF. Influenced by patterns from Infrastructure as Code pioneers and frameworks used at Netflix, Airbnb, Spotify, and Uber, it seeks to reduce boilerplate found in Terraform configurations. The project is maintained by Gruntwork, a company founded by alumni of engineering teams at companies likened to Amazon, and has been discussed at conferences including HashiConf, KubeCon, and AWS re:Invent.

Features

Terragrunt provides features such as automated remote state configuration with support for backends like Amazon S3, HashiCorp Consul, Azure Blob Storage, and Google Cloud Storage; dependency management inspired by orchestration tools such as Make (software), Jenkins, and CircleCI; and configuration inheritance similar to patterns promoted by Ansible and Puppet. It offers locking mechanisms compatible with DynamoDB and coordination patterns reminiscent of ZooKeeper and etcd. Integration points exist for secret management systems including HashiCorp Vault, AWS Secrets Manager, and Google Secret Manager. Advanced templating and DRY features echo approaches from Helm, Kustomize, Pulumi, and Serverless Framework.

Architecture and Workflow

Terragrunt operates as a thin CLI layer written in Go that parents Terraform CLI invocations, coordinating multiple Terraform modules across directory hierarchies. Typical workflows combine remote state orchestration with locking and dependency graphs that parallel systems like Argo CD and Spinnaker. State handling uses durable backends such as Amazon S3 plus locking via DynamoDB or stateful services like Consul. Workflows often integrate with CI/CD systems including GitHub Actions, GitLab CI, Jenkins, Travis CI, and CircleCI to enable automated plan/apply pipelines. For large infrastructures teams model environments and modules similarly to practices described in publications from O’Reilly Media and talks at AWS re:Invent.

Configuration and Usage

Terragrunt configuration files typically use the HCL2 syntax shared with Terraform and employ conventions for managing per-environment variables, provider configuration, and remote state blocks, similar to patterns in HashiCorp Configuration Language documentation. Users combine Terragrunt with Terraform modules sourced from registries or repositories hosted on platforms like GitHub, GitLab, Bitbucket, and artifact stores used by JFrog. Common usage includes composing module inputs, setting backend configuration, and defining dependency orders for stacks used by companies such as Pinterest and Dropbox that followed microservice infrastructure models. Integration with secret stores such as HashiCorp Vault or cloud-native solutions is common for injecting sensitive variables during runs initiated by orchestration engines like Kubernetes or Nomad.

Comparison with Terraform and Other Tools

Terragrunt is not a replacement for Terraform; it augments Terraform similarly to how tools like Atlantis and Atlantis (software) provide workflow automation, while other competitors like Pulumi and Crossplane offer alternative IaC paradigms based on general-purpose languages or Kubernetes-native APIs. Compared to configuration management tools such as Chef, Puppet, SaltStack, and provisioning orchestrators like Ansible Tower or Terraform Enterprise, Terragrunt focuses narrowly on improving Terraform module composition, remote state handling, and orchestration rather than providing a full platform for policy enforcement or a proprietary state service. Teams choosing Terragrunt often weigh trade-offs against commercial offerings like HashiCorp Terraform Enterprise and cloud-native operators for Kubernetes.

Adoption and Use Cases

Organizations with large, multi-account, multi-region infrastructures—ranging from startups to enterprises such as Netflix, Airbnb, Spotify, Uber, Shopify, Salesforce, and Oracle—have adopted patterns that Terragrunt aims to simplify, though each organization’s specific tooling choices vary. Typical use cases include managing network topologies (VPCs), IAM and identity resources, storage and databases, and platform foundations for Kubernetes clusters. Infrastructure teams integrate Terragrunt into pipelines using CI/CD platforms such as CircleCI, Jenkins, GitHub Actions, GitLab CI, and TeamCity to implement review-driven workflows inspired by GitOps and continuous deployment practices described at KubeCon.

Security and Best Practices

Security practices when using Terragrunt emphasize secrets management with HashiCorp Vault, AWS KMS, Azure Key Vault, or Google KMS; least-privilege IAM roles similar to guidance from NIST and CIS benchmarks; and auditability via logging systems like Splunk, ELK Stack, and Datadog. Best practices include storing remote state in durable backends with server-side encryption, using locks via DynamoDB or Consul to prevent concurrent writes, and integrating policy checks from frameworks like Open Policy Agent and Sentinel where organizations also use HashiCorp Terraform Enterprise. Operational patterns borrow from incident response playbooks advocated by US-CERT and service reliability guidance from Google SRE.

Category:Infrastructure as code