05_variables.adoc

Variables in Terraform

Variables in Terraform are used to define values that can be used in your configuration. They can be used to define values for your resources, or to define values that can be used in your configuration. Variables can be defined in a number of ways, including as environment variables, as command-line arguments, or in a file.

Variables in Terraform are defined using the variable block. The variable block is used to define a variable, and it can be used to define the type of the variable, the default value of the variable, and the description of the variable.

The variable block is used to define a variable, and it can be used to define the type of the variable, the default value of the variable, and the description of the variable.

variable "region" {
  description = "The region in which to create the resources."
  type        = string
  default     = "eu-west-1"
}

In the example above, we define a variable called region with a type of string, a default value of eu-west-1, and a description of The region in which to create the resources. Variables can be used in your configuration by using the var function. The var function is used to reference a variable in your configuration, and it can be used to reference the value of a variable, or to reference the type of a variable.

provider "aws" {
  region = var.region
}

We use the var function to reference the value of the region variable, and we use it to set the region attribute of the aws provider.

Variables can also be used to define values for your resources. You can use the var function to reference the value of a variable in your resource configuration, and you can use it to define the value of an attribute of a resource.

resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
  region        = var.region
}

In the example above, we use the var function to reference the value of the region variable, and we use it to set the region attribute of the aws_instance resource.

Task: Create a new variable

• Create a new variable in variables.tf for instance_type and use it in the aws_instance resource in your main.tf.

Use variables

Variables can be defined in a number of ways, including as environment variables, as command-line arguments, or in a file. You can use the terraform command-line tool to define variables using the -var flag, and you can use the TF_VAR_ prefix to define environment variables.

terraform apply -var 'region=eu-west-1'

In the example above, we use the terraform command-line tool to define the value of the region variable using the -var flag.

export TF_VAR_region=eu-west-1

In the example above, we use the TF_VAR_ prefix to define the value of the region variable as an environment variable.

Variables can also be defined in a file using the variables.tf file. The variables.tf file is used to define variables, and it can be used to define the type of the variable, the default value of the variable, and the description of the variable.

variable "region" {
  description = "The region in which to create the resources."
  type        = string
  default     = "eu-west-1"
}

In the example above, we define a variable called region with a type of string, a default value of eu-west-1, and a description of The region in which to create the resources.

Variables can also be defined in a file using the terraform.tfvars file. The terraform.tfvars file is used to define variables, and it can be used to define the value of the variable.

region = "eu-west-1"

In this example, we define the value of the region variable in the terraform.tfvars file.

Task: Use variables

• Add the instance_type variable to the terraform.tfvars file and use it in the aws_instance resource in your main.tf. Set the value to t2.micro.

• Run terraform apply to apply the changes.

• Try to find out what happens when you use the -var flag to override the value of a variable.

Next step: Destroy the infrastructure