Module 5: Reconnaissance

Sometimes you don't want to build a new resource; you just want to find information about an existing one. For this, we use Data Sources.

Tactical Intel: Data Blocks

A resource block says: "Build this." A data block says: "Find this."

Why use Data Sources?

Imagine you need to launch a server, but you need to know which subnet is available. You use a data source to ask AWS: "Give me the ID of the public subnet."

Step 1: The Query

We're going to ask Terraform to find the information about the bucket we created earlier.

Mission: Add a data block to your main.tf:

data "aws_s3_bucket" "existing_intel" {
  bucket = "terraform-mission-bucket"
}

Tactical Insight: Read-Only

Data sources are strictly Read-Only. Terraform will never modify or delete anything referenced in a data block. It is purely for gathering intelligence.