The Terraform Book

Chapter 3: Building an application stack with Terraform
Let’s update our provider with the new variables we’ve just created.
Listing 3.7: Adding our new variables
provider "aws" {
access_key = "${var.access_key}"
secret_key = "${var.secret_key}"
region = "${var.region}"
}
We’ve specified Terraform’s interpolation syntax: ${ }. Inside that syntax we’ve
specified our three variables. Each variable is identified as a variable by the var.
prefix. Currently only one of these variables has a value, the default of us-east
-1 we’ve set for the var.region variable. Soon we’ll see how to populate values
for the other variables.
TIP Since Terraform 0.8 there is a command called terraform console. The
console is a Terraform REPL that allows you to work with interpolations and other
logic. It’s a good way to explore working with Terraform syntax. You can read
about it in the console command documentation.
Maps
Most of our variable examples have, thus far, been strings. We can also specify
two other types of variables: maps and lists. Let’s look at maps first.
Maps are associative arrays and ideal for situations where you want to use one
value to look up another value. For example, one of our potential configuration
attributes is the EC2 instance’s AMI. AMIs are region specific, so if we change
Version: v1.1.1 (e771e4d) 7