terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.65.0"
    }
  }
}

provider "aws" {
  region = "ap-northeast-1"
  default_tags {
    tags = {
      env       = "test"
      provision = "terraform"
    }
  }
}

resource "aws_s3_bucket" "s3" {
}

$ terraform init
$ terraform plan
$ terraform apply

$ terraform --version
Terraform v1.4.6
on linux_amd64
+ provider registry.terraform.io/hashicorp/aws v4.65.0

Your version of Terraform is out of date! The latest version
is 1.5.0. You can update by downloading from https://www.terraform.io/downloads.html

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.65.0"
    }
  }
+  backend "s3" {
+    bucket = "<作成したバケット>"
+    key    = "<パス>"
+    region = "ap-northeast-1"
+  }
}

$ terraform init -migrate-state

Initializing the backend...
Do you want to copy existing state to the new backend?
  Pre-existing state was found while migrating the previous "local" backend to the
  newly configured "s3" backend. No existing state was found in the newly
  configured "s3" backend. Do you want to copy this state to the new "s3"
  backend? Enter "yes" to copy and "no" to start with an empty state.

  Enter a value: yes


Successfully configured the backend "s3"! Terraform will automatically
use this backend unless the backend configuration changes.

// 略

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.65.0"
    }
  }
-  backend "s3" {
-    bucket = "<作成したバケット>"
-    key    = "<パス>"
-    region = "ap-northeast-1"
-  }
}

$ terraform init -migrate-state

Initializing the backend...
Terraform has detected you're unconfiguring your previously set "s3" backend.
Do you want to copy existing state to the new backend?
  Pre-existing state was found while migrating the previous "s3" backend to the
  newly configured "local" backend. No existing state was found in the newly
  configured "local" backend. Do you want to copy this state to the new "local"
  backend? Enter "yes" to copy and "no" to start with an empty state.

  Enter a value: yes



Successfully unset the backend "s3". Terraform will now operate locally.

// 略

$ terraform init -reconfigure

Initializing the backend...

Successfully configured the backend "s3"! Terraform will automatically
use this backend unless the backend configuration changes.

// 略

$ terraform plan

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following
symbols:
  + create

Terraform will perform the following actions:

  # aws_s3_bucket.s3 will be created
// 略