3. Basics on Terraform Basics on AWS Training

3.1. Resources

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Create a new directory for this exercise:

mkdir -p $LAB_ROOT/basics/resources
cd $LAB_ROOT/basics/resources

Step 3.1.1: Create `main.tf`

We will start with a simple example by creating a resource of type random_integer. This resources generates a random number in the configured range.

Create a new file named main.tf in your working directory and paste the following:

resource "random_integer" "number" {
 min = 1000
 max = 9999
}

Explanation

The resource block defines one (or multiple) infrastructure objects which are managed by Terraform.

3.2. Variables

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Create a new directory for this exercise:

mkdir -p $LAB_ROOT/basics/variables
cd $LAB_ROOT/basics/variables

Step 3.2.1: Create variables.tf and main.tf

Create a new file named variables.tf in your working directory and add the following content:

variable "random_min_value" {
 type = number
 default = 1000
 description = "min value of the random number"
}

Create a new file named main.tf in your working directory and add the following content:

resource "random_integer" "number" {
 min = var.random_min_value
 max = 9999
}

Explanation

It is best practice putting all required input variables in the file variables.tf.

3.3. Outputs

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Finish the Variables exercise and navigate to the directory:

cd $LAB_ROOT/basics/variables

Step 3.3.1: Create outputs.tf

Create a new file named outputs.tf in your working directory and add the following content:

output "number" {
 value = random_integer.number.result
 description = "random value created by terraform"
}

Step 3.3.2: Apply the configuration

Run the command

terraform apply

and you should see output similar to this:

Plan: 0 to add, 0 to change, 0 to destroy.

Changes to Outputs:
 + number = 15670

Do you want to perform these actions?
 Terraform will perform the actions described above.
 Only 'yes' will be accepted to approve.

 Enter a value: yes


Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:

number = 15670

Step 3.3.3: Access the output

If you just want to access the output value without running apply, you can just run:

3.4. Data Sources

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Create a new directory for this exercise:

mkdir -p $LAB_ROOT/basics/data_sources
cd $LAB_ROOT/basics/data_sources

Step 3.4.1: Create resources

Create a new file named main.tf in your working directory and paste the following:

resource "random_integer" "number" {
 min = 1000
 max = 9999
}

resource "local_file" "random" {
 content = random_integer.number.result
 filename = "random.txt"
}

Step 3.4.2: Apply the configuration

Run the commands

terraform init
terraform apply

You will see on the console the resource random_integer.number is created before the local_file.random because the result attribute of the random integer is passed as content.

3.5. Types / Functions

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Create a new directory for this exercise:

mkdir -p $LAB_ROOT/basics/types
cd $LAB_ROOT/basics/types

Documentation for the built-in functions can be found at: https://www.terraform.io/docs/language/functions/index.html

Step 3.5.1: String interpolation

Create a new file named strings.tf and add the following content:

locals {
 counter = 5
}

output "counter" {
 value = "Counter is ${local.counter}"
}

Run init and apply:

terraform init
terraform apply

Step 3.5.2: Working with lists

Create a new file named lists.tf and add the following content:

locals {
 fibonacci = [0,1,1,2,3,5,8,13]
}

output "element_5" {
 value = local.fibonacci.5 // or local.fibonacci[5]
}

output "fibonacci" {
 value = join("/", local.fibonacci)
}

Run apply:

3. Basics on Terraform Basics on AWS Training

3.1. Resources

Preparation

Step 3.1.1: Create main.tf

Explanation

3.2. Variables

Preparation

Step 3.2.1: Create variables.tf and main.tf

Explanation

3.3. Outputs

Preparation

Step 3.3.1: Create outputs.tf

Step 3.3.2: Apply the configuration

Step 3.3.3: Access the output

3.4. Data Sources

Preparation

Step 3.4.1: Create resources

Step 3.4.2: Apply the configuration

3.5. Types / Functions

Preparation

Step 3.5.1: String interpolation

Step 3.5.2: Working with lists

Step 3.1.1: Create `main.tf`