Terraform_remote_state usage - Mini Project: Build & Apply

Terraform Remote State Usage

📖 Scenario: You are managing infrastructure with Terraform. You want to share outputs from one Terraform project to another safely and efficiently. This is common when you have multiple teams or layers of infrastructure.

🎯 Goal: Build a Terraform configuration that uses terraform_remote_state to access outputs from another Terraform state stored in an S3 bucket.

📋 What You'll Learn

Create a terraform_remote_state data block to read remote state from an S3 backend

Configure the remote state backend with bucket name, key, and region

Access an output variable from the remote state

Use the remote output in a local resource or variable

💡 Why This Matters

🌍 Real World

Terraform remote state is used to share infrastructure information between different teams or layers, such as networking and application layers, without duplicating code or risking inconsistencies.

💼 Career

Understanding terraform_remote_state is essential for cloud engineers and DevOps professionals who manage complex infrastructure with Terraform in collaborative environments.

1

Create terraform_remote_state data block

Create a data block named remote_state of type terraform_remote_state that reads from an S3 backend with the bucket my-terraform-states, key network/terraform.tfstate, and region us-west-2.

Terraform

# Your code here

Need a hint?

Use a data block with type terraform_remote_state and specify the S3 backend configuration inside config.

2

Add a local variable to hold remote output

Add a locals block with a variable named vpc_id that gets the value from data.remote_state.outputs.vpc_id.

Terraform

data "terraform_remote_state" "remote_state" {
  backend = "s3"
  config = {
    bucket = "my-terraform-states"
    key    = "network/terraform.tfstate"
    region = "us-west-2"
  }
}

# Your code here

Need a hint?

Use a locals block and assign vpc_id to the remote state's output value.

3

Use the remote output in a resource

Create a resource aws_subnet named example_subnet that uses local.vpc_id for its vpc_id attribute. Set cidr_block to "10.0.1.0/24" and availability_zone to "us-west-2a".

Terraform

data "terraform_remote_state" "remote_state" {
  backend = "s3"
  config = {
    bucket = "my-terraform-states"
    key    = "network/terraform.tfstate"
    region = "us-west-2"
  }
}

locals {
  vpc_id = data.terraform_remote_state.remote_state.outputs.vpc_id
}

# Your code here

Need a hint?

Define an aws_subnet resource using the local variable vpc_id and set the other attributes as specified.

4

Add provider configuration

Add a provider block for aws with the region set to "us-west-2".

Terraform

data "terraform_remote_state" "remote_state" {
  backend = "s3"
  config = {
    bucket = "my-terraform-states"
    key    = "network/terraform.tfstate"
    region = "us-west-2"
  }
}

locals {
  vpc_id = data.terraform_remote_state.remote_state.outputs.vpc_id
}

resource "aws_subnet" "example_subnet" {
  vpc_id            = local.vpc_id
  cidr_block        = "10.0.1.0/24"
  availability_zone = "us-west-2a"
}

# Your code here

Need a hint?

Define the AWS provider block with the correct region to enable resource creation.