Referencing the Five Basic Types of Terraform Config Files

The aim of this page📝 is to explain the five basic types of terraform config files. Config_files represent one of the four major component of terraform itself, besides 1. single executable (terraform) 2. plugins (e.g. aws/gcp provider) and 3. state_files

A common approach is to

• put your resources in a main.tf file
• inputs in variables.tf
• outputs in outputs.tf.

Additionally, you can also create a modules sub-folder for any private sub-modules you make (private means they are not intended for use in other modules). Also, you can create an examples folder that contains examples in subfolders, and a README that describes the module's use. Here's an example folder structure for a module in the git repo terraform-aws-pavol:

terraform-aws-pavol
├── examples
│   └── simple
│       └── main.tf
├── modules
│   ├── lambda_function
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── outputs.tf
│   └── ecs
│       ├── main.tf
│       ├── variables.tf
│       └── outputs.tf
├── main.tf
├── variables.tf
├── outputs.tf
└── README.md

1. variables to create necessary abstractions, usually places in variables.tf

variable "aws_access_key" {}
variable "aws_secret_key" {}
variable "aws_region" {
    default = "us-east-1"
}

• create necessary abstractions for storing data, for example to hold aws access keys, region to be used, etc.
• usually the top of the file

2. providers to deploy an environment with its specific requirements such are region or secrets

provider "aws" {
    access_key = "var.access_key"
    secret_key = "var.secret_key"
    region = "var.aws_region"
}

• deploy environment
• you pass the variables
• connect to AWS by defining a provider
• AWS is a provider, a platform you are building your
• provider properties are in docs

3. datasources obtaining data about services such as available AMIs or information about AZs

data "aws_ami" "alx" {
    most_recent = true
    owners = ["amazon"]
    filters {}
}

• query the cloud for the datasource that may be used later as a deploy input
• you pull a DATA SOURCE — querying an informatino about that provider
• if getting all amazon linux ami
• or, you could be pulling information about availability zone

4. resources that are created within the public cloud, usually put in main.tf

resource "aws_instance" "ex" {
    ami = "data.ams_ami.alx.id"
    instance_type = "t2.micro"
}

• deployment INPUT
• you create a resource or deploy a resource
• we’re going to be creating a server
• this is what is needed to be created
• resource takes several parameters to be created or passed as a variable or as a data source

5. output — data produced by the deployment that may be usefulel, usually in output.tf

• for example public IP address

output "aws_public_ip" {
    value = "aws_instance.ex.public.dns"
}

6. sources

• Terraform — Getting Started @ Pluralsight