How are data sources used in Terraform?

Question

The Terraform Data Sources documentation tells me what a data source is, but I do not quite understand it. Can somebody give me a use case of data source? What is the differ

Answer 1

Data sources are used to fetch the data from the provider end, so that It can be used as configuration in .tf files, Instead of hardcoding it. Example: Below code fetches the AWS AMI ID and uses it to launch AWS instance.

data "aws_ami" "std_ami" {
  most_recent = true
  owners      = ["amazon"]

filter {
    name   = "root-device-type"
    values = ["ebs"]
  }

filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }
}

resource "aws_instance" "myec2" {
  ami           = data.aws_ami.std_ami.id
  instance_type = "t2.micro"
}