chore: sample for S3 as terraform backend (#293)

* chore: sample for S3 as terraform backend

* chore: Update documentation fixes

* fix: fixes for fmt errors

---------

Co-authored-by: Christian Lechner <[email protected]>

Author: prajin-op

released/terraform-be/README.md

@@ -18,4 +18,4 @@ As mentioned the default backend stores state as a local file on disk. It is sui
 
 ### Kubernetes Backend
 
-The [Kubernetes backend](https://developer.hashicorp.com/terraform/language/settings/backends/kubernetes) stores state in a Kubernetes secret and supports state locking using a Lease resource. It allows for secure and collaborative state management in Kubernetes environments. You find a sample technical setup in the directory [k8sasbackend](./k8sasbackend/README.md)
+The [Kubernetes backend](https://developer.hashicorp.com/terraform/language/settings/backends/kubernetes) stores state in a Kubernetes secret and supports state locking using a Lease resource. It allows for secure and collaborative state management in Kubernetes environments. You find a sample technical setup in the directory [k8sasbackend](./k8sasbackend/README.md)

released/terraform-be/s3asbackend/README.md

@@ -0,0 +1,17 @@
+# Backend as S3
+
+The Terraform S3 [backend](https://developer.hashicorp.com/terraform/language/settings/backends/s3) allows you to store the Terraform state files in an Amazon S3 bucket, providing a centralized, reliable, and durable storage solution.
+
+## Example Configuration
+
+```terraform
+terraform {
+  backend "s3" {
+    bucket         = "<Name of your S3 bucket>"
+    key            = "terraform/state"
+    region         = "<Region>"
+    encrypt        = true
+    acl            = "bucket-owner-full-control"
+  }
+}
+```

released/terraform-be/s3asbackend/backend.tf

@@ -0,0 +1,9 @@
+terraform {
+  backend "s3" {
+    bucket  = "btpterraformbackend"
+    key     = "terraform/state"
+    region  = "eu-north-1"
+    encrypt = true
+    acl     = "bucket-owner-full-control"
+  }
+}

released/terraform-be/s3asbackend/main.tf

@@ -0,0 +1,26 @@
+###############################################################################################
+# Creation of subaccount
+###############################################################################################
+resource "random_uuid" "uuid" {}
+
+resource "btp_subaccount" "project" {
+  name      = var.subaccount_name
+  subdomain = "${var.subaccount_name}-${random_uuid.uuid.result}"
+  region    = lower(var.region)
+}
+
+######################################################################
+# Add entitlement for BAS, Subscribe BAS and add roles
+######################################################################
+resource "btp_subaccount_entitlement" "bas" {
+  subaccount_id = btp_subaccount.project.id
+  service_name  = "sapappstudio"
+  plan_name     = var.bas_plan_name
+}
+
+resource "btp_subaccount_subscription" "bas-subscribe" {
+  subaccount_id = btp_subaccount.project.id
+  app_name      = "sapappstudio"
+  plan_name     = var.bas_plan_name
+  depends_on    = [btp_subaccount_entitlement.bas]
+}

released/terraform-be/s3asbackend/provider.tf

@@ -0,0 +1,8 @@
+terraform {
+  required_providers {
+    btp = {
+      source  = "sap/btp"
+      version = "~> 1.5.0"
+    }
+  }
+}

released/terraform-be/s3asbackend/variables.tf

@@ -0,0 +1,32 @@
+######################################################################
+# Customer account setup
+######################################################################
+# subaccount
+variable "globalaccount" {
+  type        = string
+  description = "The globalaccount subdomain."
+}
+# subaccount
+variable "subaccount_name" {
+  type        = string
+  description = "The subaccount name."
+}
+# Region
+variable "region" {
+  type        = string
+  description = "The region where the project account shall be created in."
+  default     = "us10"
+}
+# CLI server
+variable "cli_server_url" {
+  type        = string
+  description = "The BTP CLI server URL."
+  default     = "https://cli.btp.cloud.sap"
+}
+
+# Plan_name update
+variable "bas_plan_name" {
+  description = "BAS plan"
+  type        = string
+  default     = "standard-edition" #For production use of Business Application Studio, upgrade the plan from the `free-tier` to the appropriate plan e.g standard-edition
+}