Terragrunt for Beginners
Terragrunt Attributes
download dir Attribute
In this lesson, we’ll dive into the download_dir attribute in Terragrunt. This setting lets you control where Terraform module sources are cached before running any Terraform command, helping you maintain a clean workspace and isolate module downloads per project or environment.
What Is download_dir?
- Purpose: Defines the folder on your local file system where Terragrunt will store downloaded Terraform configurations and module dependencies.
- Type: String (absolute or relative path).
- Use Cases:
- Organizing module downloads by project.
- Separating cache directories for different environments or teams.
- Keeping CI/CD pipelines’ caches isolated.
Note
The download_dir path can be absolute or relative. If the directory doesn’t exist, Terragrunt will attempt to create it.
Key Benefits
| Benefit | Details |
|---|---|
| Customization | Select any directory to store Terraform modules instead of the default cache. |
| Organization | Keep downloaded modules apart from your working files and avoid clutter. |
| Isolation | Use different download directories for separate pipelines, teams, or environments. |
Considerations
- Ensure the specified directory exists or is creatable by Terragrunt.
- Verify file-system permissions to allow read/write operations.
- Confirm sufficient disk space is available to store module downloads.
Warning
If download_dir lacks write permissions or runs out of space, Terragrunt may fail during init, interrupting your Terraform workflow.
Demonstration
Default Behavior
With no download_dir set in your terragrunt.hcl, Terragrunt uses a hidden cache folder under your current working directory:
~/workspace/vpc
$ terragrunt init
INFO[0000] Downloading Terraform configurations from tfr://terraform-aws-modules/vpc/aws?version=5.8.1 \
into /workspace/vpc/.terragrunt-cache/5eyWb_1sjaAZ9XRFnWys_PGxK0E/ThyVwttki6d6ASaD5OwoqIWA
...
Terraform has been successfully initialized!
Custom Download Directory
Add download_dir to your terragrunt.hcl at the root of your module:
terraform {
source = "tfr://terraform-aws-modules/vpc/aws//?version=5.8.1"
}
include "root" {
path = find_in_parent_folders()
expose = true
}
download_dir = "../.terragrunt-kodekloud"
inputs = {
name = "KodeKloud-VPC"
cidr = "10.100.0.0/16"
}
Running initialization again stores the module cache in your custom directory:
~/workspace/vpc
$ terragrunt init
INFO[0000] Downloading Terraform configurations from tfr://terraform-aws-modules/vpc/aws?version=5.8.1 \
into ../.terragrunt-kodekloud/5eyWb_lsjAZ9XrfnWJs_pGxNOE/ThyYwttki6d6ASaD5OwoqIAW
Initializing the backend...
Initializing provider plugins...
- Reusing previous versions of hashicorp/aws from the dependency lock file
- Installing hashicorp/aws v5.52.0...
Terraform has been successfully initialized!
Notice the cache now resides under ../.terragrunt-kodekloud instead of the default .terragrunt-cache.
Links and References
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