Terraform AWS – Day 04: Understanding tfstate File & Remote Storage in S3

Yesterday, I built my first VPC with subnets, route tables, and an internet gateway. But while doing that, I realized something important: how does Terraform even “remember” what it has created?

That’s where the terraform.tfstate file comes in.

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🔹 What is terraform.tfstate?

The terraform.tfstate file is where Terraform keeps the current state of your infrastructure.

Think of it like Terraform’s memory — it knows:

• Which resources exist (EC2, VPCs, subnets, etc.)

• Their configurations (AMI IDs, IPs, tags, etc.)

• Any dependencies between them

👉 Without this file, Terraform wouldn’t know what’s deployed and would keep trying to recreate resources every time.

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🔹 Why is it Important?

1. Tracks Infrastructure → Terraform knows exactly what exists.

2. Sync Between Teams → Multiple people can work without overwriting each other’s changes.

3. Avoids Drift → If someone changes infra outside Terraform (like manually in AWS), Terraform will detect it by comparing against state.

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🔹 Where Can You Store tfstate?

By default, Terraform stores terraform.tfstate locally in your project folder. But in real-world scenarios, that’s risky because:

❌ If your laptop crashes, you lose state.
❌ Teams can’t collaborate properly.
❌ Risk of overwriting infra.

✅ Best practice → Store state remotely in the cloud. Terraform supports backends like:

• S3 (AWS)

• GCS (Google Cloud)

• Azure Blob Storage

• Terraform Cloud

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🔹 Practical Demo: Store State in S3

Here’s how I configured Terraform to store the state file in AWS S3:

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "6.8.0"
    }
  }

  backend "s3" {
    bucket = "mybucket-8964366a63341c51"
    key    = "backend-tfstate"
    region = "ap-south-1"
  }
}

provider "aws" {
  region = "ap-south-1"
}

resource "aws_instance" "myserver" {
  ami           = "ami-0144277607031eca2"
  instance_type = "t2.micro"

  tags = {
    my = "server"
  }
}

🔍 What this does:

• Creates an EC2 instance (just for demo)

• Saves the state file in S3 instead of locally

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🔹 Key Takeaways from Day 04

• terraform.tfstate is Terraform’s source of truth

• Always store it remotely for safety & collaboration

• S3 is the most common backend for AWS users

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🔗 Follow My Journey

💻 Code: GitHub
🐦 Updates: X (Twitter)

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