How to Create an RDS Instance with Terraform

To create an RDS instance with Terraform, define an aws_db_instance resource specifying engine, instance class, and credentials. Then run terraform init, terraform plan, and terraform apply to deploy the database.

Syntax

The aws_db_instance resource creates an RDS instance. Key parts include:

• identifier: a unique name for your database instance.
• engine: type of database (e.g., mysql, postgres).
• instance_class: size and power of the instance.
• username and password: credentials for the database.
• allocated_storage: storage size in GB.

terraform

resource "aws_db_instance" "example" {
  identifier         = "mydb-instance"
  engine             = "mysql"
  instance_class     = "db.t3.micro"
  allocated_storage  = 20
  username           = "admin"
  password           = "mypassword"
  skip_final_snapshot = true
}

Example

This example creates a MySQL RDS instance with basic settings. It uses a small instance class and 20 GB storage. The password is set directly for simplicity but should be stored securely in real projects.

terraform

provider "aws" {
  region = "us-east-1"
}

resource "aws_db_instance" "example" {
  identifier          = "mydb-instance"
  engine              = "mysql"
  instance_class      = "db.t3.micro"
  allocated_storage   = 20
  username            = "admin"
  password            = "mypassword"
  skip_final_snapshot = true
  publicly_accessible = true
}

Output

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Outputs:

aws_db_instance.example: Creation complete after 5m30s [id=mydb-instance]

Common Pitfalls

Common mistakes when creating RDS instances with Terraform include:

• Not setting skip_final_snapshot to true during testing, which causes apply to fail if a snapshot is required.
• Hardcoding passwords in code instead of using secure methods like Terraform variables or AWS Secrets Manager.
• Forgetting to specify engine or using unsupported engine names.
• Choosing an instance class not supported in your AWS region.

terraform

resource "aws_db_instance" "wrong" {
  identifier        = "bad-instance"
  instance_class    = "db.t3.micro"
  allocated_storage = 20
  username          = "admin"
  password          = "password"
  # Missing engine causes error
}

# Correct way:
resource "aws_db_instance" "right" {
  identifier          = "good-instance"
  engine              = "mysql"
  instance_class      = "db.t3.micro"
  allocated_storage   = 20
  username            = "admin"
  password            = "password"
  skip_final_snapshot = true
}

Quick Reference

Property	Description	Example
identifier	Unique name for the DB instance	"mydb-instance"
engine	Database engine type	"mysql", "postgres"
instance_class	Size/type of instance	"db.t3.micro"
allocated_storage	Storage size in GB	20
username	Master username	"admin"
password	Master password	"mypassword"
skip_final_snapshot	Skip snapshot on deletion	true

Key Takeaways

Use the aws_db_instance resource with required properties like engine and instance_class.

Always set skip_final_snapshot=true during testing to avoid apply errors.

Store sensitive data like passwords securely, not hardcoded in code.

Check AWS region support for your chosen instance class and engine.

Run terraform init, plan, and apply to deploy your RDS instance.