How to Use the AWS account_id Variable in Terraform

TLDR

To use the AWS account_id variable in Terraform, leverage the aws_caller_identity data source. This allows you to dynamically retrieve the account ID for use in your configurations.

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The AWS account_id is a unique identifier for your AWS account. In Terraform, you can dynamically retrieve this value using the aws_caller_identity data source. This guide will show you how to use the account_id variable effectively.

Why Use the account_id Variable?

• Dynamic Configurations: Avoid hardcoding the account ID in your Terraform files.
• Multi-Account Setups: Simplify configurations for environments spanning multiple AWS accounts.
• Security: Reduce the risk of errors caused by incorrect account IDs.

Retrieving the account_id

Use the aws_caller_identity data source to retrieve the account ID dynamically.

Example: Using aws_caller_identity

data "aws_caller_identity" "current" {}

output "account_id" {
  value = data.aws_caller_identity.current.account_id
}

In this example, the account_id is retrieved and displayed as an output.

Using the account_id in Resources

You can use the account_id variable in resource definitions to make your configurations dynamic.

Example: S3 Bucket Naming

resource "aws_s3_bucket" "example" {
  bucket = "example-bucket-${data.aws_caller_identity.current.account_id}"
  acl    = "private"
}

This configuration creates an S3 bucket with a name that includes the account ID.

Best Practices

• Avoid Hardcoding: Always use the aws_caller_identity data source to retrieve the account ID dynamically.
• Use Outputs: Export the account_id as an output for reuse in other configurations.
• Test in Non-Production: Validate your configurations in a non-production environment before applying them to production.

By using the AWS account_id variable dynamically, you can create more flexible and secure Terraform configurations that adapt to different environments and accounts.