Terraform Series

Understanding Providers and Variables in Terraform

Hari Lachannagari's photo
Hari Lachannagari
·

2 min read

Terraform, as an Infrastructure as Code (IaC) tool, enables the declarative configuration and provisioning of infrastructure resources. Two key concepts that every Terraform user must grasp are providers and variables. Let’s dive into these concepts to understand their purpose and usage.

What are Providers in Terraform?

Providers are plugins that enable Terraform to interact with cloud providers, SaaS platforms, and other APIs. Providers allow Terraform to manage infrastructure resources specific to a platform, such as AWS, Azure, or Kubernetes.

Key Features:

  1. Providers handle authentication and interaction with the target platform.

  2. They define the resource types that Terraform can manage.

  3. Providers must be declared in every Terraform configuration.

provider "aws" {
  region = "us-east-1"
}

The AWS provider is configured to operate in the "us-east-1" region.

What are Variables in Terraform?

Variables are placeholders used to parameterize Terraform configurations. They allow you to reuse configurations by abstracting values that might change across environments or deployments.

Types of Variables:

  1. Input Variables: Used to provide external values to a Terraform configuration.

  2. Environment Variables: Set in the system environment and used by Terraform for various purposes (e.g., authentication credentials).

  3. Output Variables: Provide information about the infrastructure resources after execution.

Declaring Variables:
variable "instance_type" {
  description = "Type of EC2 instance"
  type        = string
  default     = "t2.micro"
}

  1. A terraform.tfvars file.

  2. Command-line flags: terraform apply -var='instance_type=t2.large'

  3. Environment variables: TF_VAR_instance_type=t2.large

Using Providers with Variables

Combining providers and variables makes Terraform configurations dynamic and flexible. For example:

# Defining a variable for the region
variable "region" {
  default = "us-east-1"
}

# Using the variable in a provider
provider "aws" {
  region = var.region
}

This setup enables you to change the region dynamically by altering the region variable’s value.

Dynamic Credentials Example:

Using environment variables for credentials ensures sensitive data is not hardcoded:

provider "aws" {
  region     = var.region
  access_key = var.aws_access_key
  secret_key = var.aws_secret_key
}

variable "aws_access_key" {}
variable "aws_secret_key" {}

You can then set the environment variables TF_VAR_aws_access_key and TF_VAR_aws_secret_key for secure configuration.

Best Practices:

  1. Use Default Values: Define sensible defaults for variables to avoid errors in deployments.

  2. Separate Variables: Use a variables.tf file to keep variables organized.

  3. Secure Sensitive Data: Leverage Terraform’s sensitive flag for variables containing secrets.

  4. Lock Provider Versions: Ensure stable deployments by locking provider versions using constraints.

Providers and variables are foundational to Terraform configurations. By mastering these concepts, you can create modular, reusable, and secure infrastructure code that adapts seamlessly to various environments. Start experimenting with different providers and variable types to build a strong Terraform foundation!

Terraform#IaCAWSDevops