4. Secrets Manager

terraform/secrets/mainf.tf

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.62.0"
    }
  }

  required_version = ">= 1.0.8"
}

provider "aws" {
  region = "eu-central-1"
}

resource "random_password" "password" {
  length           = 16
  special          = true
  override_special = "_%@"
}

resource "random_id" "db_secret_suffix" {
  byte_length = 8
}

resource "aws_secretsmanager_secret" "db_secret" {
  name = "db-secret-${random_id.db_secret_suffix.b64_std}"
}

resource "aws_secretsmanager_secret_version" "db_secret_version" {
  secret_id = aws_secretsmanager_secret.db_secret.id
  secret_string = jsonencode({
    name     = "workshopsdb"
    username = "workshopsuser"
    password = random_password.password.result
  })
}

If you want to keep database name and username secure you can create input variables and pass its values via environment variables that match the pattern TF_VAR_<VARIABLE_NAME>. You can learn more about this topic here. Also, you can use HashiCorp Vault to manage secrets.

terraform/secrets/outputs.tf

output "db_secert_arn" {
  value = aws_secretsmanager_secret_version.db_secret_version.arn
}

Try to read the secret's value using the AWS CLI:

$ aws secretsmanager get-secret-value --secret-id aws secretsmanager get-secret-value --secret-id arn:aws:secretsmanager:eu-central-1:852046301552:secret:db-secret-WNqgLUG8tGI=-5EzeJ8

{
    "ARN": "arn:aws:secretsmanager:eu-central-1:852046301552:secret:db-secret-WNqgLUG8tGI=-5EzeJ8",
    "Name": "db-secret-WNqgLUG8tGI=",
    "VersionId": "4FF5D96B-24A9-4712-804B-BCD4D1AF3D6B",
    "SecretString": "{\"name\":\"workshopsdb\",\"password\":\"iypoEyxNfmcWeqnZ\",\"username\":\"workshopsuser\"}",
    "VersionStages": [
        "AWSCURRENT"
    ],
    "CreatedDate": "2021-10-17T21:08:18.435000+02:00"
}

Our application will need to read the secret's value to be able to connect to the database. We need to make sure we can read the secret's value from the EC2 instance which is running in the private subnet. First, we need to create IAM Role that the EC2 instance will use.

IAM Role is a way of giving some privileges to some AWS resource to let it do something with another AWS resource.