What are Terraform providers and how do you configure them?

Providers are plugins that let Terraform work with cloud platforms, SaaS providers and other APIs. Each one defines the resource types and data sources you can use, such as aws_instance.

You configure a provider in two blocks. required_providers declares its source address and a version constraint, and terraform init downloads a matching release. The provider block sets options such as the region.

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = "us-west-2"
}

Here ~> 5.0 accepts any 5.x release but never 6.0, so a major upgrade cannot arrive by surprise.