This is my Day 2 of 30daysofawsterraform. Thanks to
Piyush Sachdeva for the amazing series. So, let’s begin.
Before writing Terraform code or creating any AWS resources, you must understand Terraform Providers — because providers are the heart of Terraform.
What is a Terraform Provider?
A provider is a plugin that connects Terraform with the external service you want to manage.
Think of it like a translator:
- You write Terraform in HCL (HashiCorp Configuration Language)
- AWS, Azure, GCP, Docker, Kubernetes — they don’t understand HCL
- So the provider converts your Terraform code → into the API calls that AWS/Azure/GCP understand.
Example:
If you write Terraform to create an S3 bucket, Terraform uses:
- AWS provider
- Which calls the AWS S3 API
- And creates the bucket for you
So Terraform never creates resources directly — the provider does it for you.
Terraform has 3 types of providers:
- Official Providers
Maintained by HashiCorp
Examples:
- AWS
- Azure
- GCP
- Partner Providers
Maintained by the official company but not HashiCorp
Example:
- Cloudflare
- Datadog
- Community Providers
Maintained by the open-source community
Example:
- Random
- HTTP provider
- Local provider
Where Providers Live: registry.terraform.io
When you search “Terraform AWS provider” on Google, you see:
registry.terraform.io/providers/hashicorp/aws
This page shows:
- All services supported by the AWS provider
- All available resource types (EC2, VPC, IAM, S3, etc.)
- All version numbers
- Documentation
- Example usage
How Does Terraform Download a Provider?
When you run:
terraform init
Terraform:
- Reads your provider block
- Contacts the Terraform Registry
- Downloads the correct provider version
- Stores it in a folder called .terraform
This folder contains:
- Provider plugin (binary)
Lock files
Based on OS, the plugin file(provider) format changes; created after “tf init”:Windows → .exe
Mac → .darwin
Linux → .linux
Provider Block Explained
A basic provider block looks like:
terraform {
required_providers {
aws = {
source = "hashicorp/aws"
version = "~> 6.0"
}
}
}
provider "aws" {
region = "us-east-1"
}
Key Points:
required_providers
Defines:
- Which providers Terraform should use
- Version of each provider
⚠️ Never hard-code AWS access key + secret key inside provider block — security risk.
Provider Version vs Terraform Version
There are TWO versions:
Terraform Core version
Example:
required_version = ">= 1.0"
Provider version
Example:
version = "~> 6.0"
These versions are independent, meaning:
- Terraform core is maintained by HashiCorp
- AWS provider is maintained by AWS
Because both are maintained separately → compatibility issues can happen
That’s why we lock provider versions.
Version Constraint Operators (Very Important)
You saw symbols like:
- = Equal to
- != Not equal
- > / < Greater/less
~> Pessimistic operator (most used)
Most important one: ~> (tilde greater-than)
Example:
version = "~> 6.0"
This means:Accept version 6.0.x
Accept version 6.1, 6.2… 6.10
❌ BUT don’t accept 7.0+ (major version changes)
This protects you from breaking changes.
Why Not Always Use Latest Provider Version?
Because:
- New versions may introduce breaking changes
- Some resources may behave differently
- Your Terraform code may break
So we lock versions until we test the newer ones in a dev environment.
Creating Resources Using Providers
A resource example:
resource "aws_vpc" "example" {
cidr_block = "10.0.0.0/16"
}
Explanation:
- resource → Terraform keyword
- "aws_vpc" → resource type from provider
- "example" → local Terraform name (internal reference)
You can refer to this resource elsewhere:
vpc_id = aws_vpc.example.id
Commands Used
- Initialize provider
terraform init
- Check what Terraform will create
terraform plan
Shows:
- What will be added
- What will be changed
- What will be destroyed
- Apply changes (create actual resource)
terraform apply
Why Your Plan Failed?
It failed because:
- Your IAM user only had S3 access
- But you tried to create VPC
- So AWS denied it
Terraform plan doesn’t call the API → but apply will fail.
Terraform State (not explained deeply here)
Terraform creates a file:
terraform.tfstate
This file:
- Tracks what resources Terraform manages
- Compares real environment vs Terraform code
- Ensures idempotency (same outcome every time)
State is a very big topic — later in your series.
Summary (Super Easy)
