Terraform snippet here that would instantiate a Postgres RDS in AWS (Sydney region)

terraform-aws-rds-postgres-instance.tf

# Have the provider and terraform block of code in a file called provider.tf 
provider "aws" {
  region = "ap-southeast-2"
}

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.16"
    }
  }

  required_version = ">= 1.2.0"
}

# Have the resource "aws_rds_instance" in a file called main.tf
resource "aws_db_instance" {
  db_name = var.rds_inst_id
  engine = "postgres"
  engine_version = 14
  instance_class = var.instance_class
  allocated_storage = var.allocated_storage
  storage_type = var.storage_type
  username = var.postgres_username
  password = var.postgres_password
  skip_final_snapshot  = true
}

# Place the below variable(s) in a seperate file called variables.tf
variable "rds_inst_id" {
  type = string
  description = "RDS Instance Identifer"
  default = "demo-rds-instance"
}

variable "instance_class" {
  type = string
  description = "RDS Instance Class"
  default = "db.t2.micro"
}

variable "allocated_storage" {
  type = number
  description = "RDS Instance Allocated Storage"
  default = "db.t2.micro"
}

variable "storage_type" {
  type = string
  description = "RDS Instance Storage Type"
  default = "gp2"
}

variable "postgres_username" {
  description = "RDS Instance Database administrator username"
  type  = string
  sensitive = true
  default = "secureusername"
}

variable "postgres_password" {
  description = "RDS Instance Database administrator password"
  type = string
  sensitive = true
  default = "securepassword"
}

# Create an outputs.tf file to log mentioned values to the console output
output "id" {
  description = "The RDS Instance Identifier."
  value       = aws_db_instance.main.id
}

output "resource_id" {
  description = "The RDS Resource ID of this instance"
  value       = aws_db_instance.main.resource_id
}

output "arn" {
  description = "The ARN of the RDS instance"
  value       = aws_db_instance.main.arn
}

output "endpoint" {
  description = "The hostname of the RDS instance."
  value       = aws_db_instance.main.address
}

output "port" {
  description = "The database port."
  value       = aws_db_instance.main.port
}

output "username" {
  description = "Username for the master DB user."
  value       = aws_db_instance.main.username
}

output "database_name" {
  description = "The database name."
  value       = aws_db_instance.main.name
}

# Create a file called secrets.tfvars to fill in the values for database username and password
postgres_username = "admin"
postgres_password = "insecurepassword"

# To execute the terraform code use `terraform apply -var-file="secret.tfvars"` 
# If we want to override the secrets, then we can do the following
  # export TF_VAR_postgres_username=supersecureusername TF_VAR_postgres_password=supersecurepassword