====== Providing Values for Variables ======

Values for variables can be provided in several ways:

===== Command-line Flags =====
Use the -var option with terraform apply or terraform plan.

<code hcl>terraform apply -var="instance_type=t2.large"</code>

===== Variable Definition Files =====

Define variables in a .tfvars file or .tfvars.json file. 

<code hcl>
// variables.tfvars
instance_type = "t2.large"
availability_zones = ["us-west-2a", "us-west-2b"]
</ocde>

<code hcl>
// variables.tfvars.json
{
  "instance_type": "t2.large",
  "availability_zones": ["us-west-2a", "us-west-2b"]
}
</code>

Apply these with the -var-file flag:

<code hcl>
terraform apply -var-file="variables.tfvars"
</code>

===== Environment Variables =====

Prefix the variable name with TF_VAR_ and set it as an environment variable.

<code hcl>
export TF_VAR_instance_type="t2.large"
terraform apply
</code>