Data Sources in Terraform resources explained with example

• Data sources provide dynamic information about entities that are not managed by the current Terraform and configuration.
• Variables provide static information.
• Referencing a resource defined in a data source won’t create the resource itself, and your plan will fail if you reference nonexistent data or infrastructure.
• Data sources allow data to be fetched or computed for use elsewhere in Terraform configuration.
• External data sources must return information in JSON format.

This may include:

• Configuration data from Consul
• Information about the state of manually-configured infrastructure components
• Another Terraform configuration
• Defined outside of Terraform
• Defined by another separate Terraform configuration.

data "azurerm_virtual_machine" "example" {
  name                = "simple-vm"
  resource_group_name = "demo"
}

output "virtual_machine_id" {
  value = data.azurerm_virtual_machine.example.id
}Code language: JavaScript (javascript)

data "aws_ami" "ubuntu" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-amd64-server-20230325"]
  }

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

  owners = ["099720109477"] # Canonical
}

data "aws_availability_zones" "available" {
  state = "available"
}

output "virtual_machine_id" {
  value = data.aws_availability_zones.available.names[0]
}

output "virtual_machine_id1" {
  value = data.aws_availability_zones.available.names[1]
}


output "ips_with_list_interpolation" {
  value = [ for name in data.aws_availability_zones.available.names : name ]
}

resource "aws_instance" "first-ec2" {
  ami           = data.aws_ami.ubuntu.id # us-west-2
  instance_type = "t2.micro"
  tags = {
    Name = "RajeshKumar"
  }
  }
  
Code language: PHP (php)

Here’s an example of using the AWS data source in Terraform to retrieve information about an existing Amazon S3 bucket

In this example, we’re using the aws_s3_bucket data source to retrieve information about an existing S3 bucket named example-bucket. We’re then outputting several attributes of the bucket using the output block.

The aws_s3_bucket data source retrieves the specified bucket’s attributes such as bucket, region, arn, policy, id, acceleration_status, versioning, website_domain, website_endpoint, and logging as per the below documentation. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/s3_bucket

data "aws_s3_bucket" "example" {
  bucket = "example-bucket"
}

output "bucket_name" {
  value = data.aws_s3_bucket.example.bucket
}

output "bucket_region" {
  value = data.aws_s3_bucket.example.region
}

output "bucket_arn" {
  value = data.aws_s3_bucket.example.arn
}

output "bucket_policy" {
  value = data.aws_s3_bucket.example.policy
}
Code language: JavaScript (javascript)

Here’s an example of using the AWS data source in Terraform to retrieve information about an existing availability zone

In this example, we’re using the aws_availability_zone data source to retrieve information about the availability zone named us-west-2a in the US West (Oregon) region. We’re then outputting the zone_id and zone_name attributes of the availability zone using the output block.

The aws_availability_zone data source retrieves the specified availability zone’s attributes such as zone_id, zone_name, region_name, and opt_in_status as per the below documentation. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/availability_zone

data "aws_availability_zone" "example" {
  state = "available"
  name  = "us-west-2a"
}

output "zone_id" {
  value = data.aws_availability_zone.example.zone_id
}

output "zone_name" {
  value = data.aws_availability_zone.example.zone_name
}
Code language: JavaScript (javascript)

Rajesh Kumar

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