Enhancement: Request: Add support for RDS Proxy Target Groups

[jrindy-iterable]

Request

It would be great if Moto added support for db proxy target groups. According to the RDS feature list it is missing both the describe and modify action: [ ] describe_db_proxy_target_groups & [] modify_db_proxy_target_group. Using the following code, Terraform eventually times out after a long while and gives the following error:

# Error
│ Error: updating RDS DB Proxy Default Target Group (testdb): operation error RDS: ModifyDBProxyTargetGroup, exceeded maximum number of attempts, 25, https response error StatusCode: 500, RequestID: , error while deserializing xml error response: XML syntax error on line 2: unquoted or missing attribute value in element
│ 
│   with aws_db_proxy_default_target_group.main,
│   on rds.tf line 30, in resource "aws_db_proxy_default_target_group" "main":
│   30: resource "aws_db_proxy_default_target_group" "main" {

Thank you!

Reproduction

providers.tf

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
    }
  }
}

provider "aws" {
  region                      = "us-east-1"
  s3_use_path_style           = true
  skip_credentials_validation = true
  skip_metadata_api_check     = true
  skip_requesting_account_id  = true

  endpoints {
    ec2            = "http://localhost:5000"
    iam            = "http://localhost:5000"
    rds            = "http://localhost:5000"
    secretsmanager = "http://localhost:5000"
  }

  access_key = "my-access-key"
  secret_key = "my-secret-key"
}

rds-prereqs.tf

data "aws_vpc" "default" {
  default = true
}

data "aws_subnets" "all" {
  filter {
    name   = "vpc-id"
    values = [data.aws_vpc.default.id]
  }
}

resource "random_string" "this" {
  length  = 4
  special = false
  upper   = false
}

resource "aws_secretsmanager_secret" "test" {
  name = "rds/test/test_admin"
}

resource "aws_secretsmanager_secret_version" "test" {
  secret_id = aws_secretsmanager_secret.test.id
  secret_string = jsonencode({
    username = "test_admin"
    password = "${random_string.this.result}"
  })
}

data "aws_iam_policy_document" "rds_trust_policy" {
  statement {
    effect = "Allow"

    principals {
      type        = "Service"
      identifiers = ["rds.amazonaws.com"]
    }

    actions = [
      "sts:AssumeRole",
    ]
  }
}

resource "aws_iam_role" "proxy" {
  assume_role_policy = data.aws_iam_policy_document.rds_trust_policy.json
  name               = "rds-proxy-${aws_db_instance.test.db_name}"
}

rds.tf

resource "aws_db_instance" "test" {
  allocated_storage   = 10
  db_name             = "testdb"
  engine              = "postgres"
  engine_version      = "15"
  instance_class      = "db.t3.micro"
  username            = "test"
  password            = random_string.this.result
  skip_final_snapshot = true
}

resource "aws_db_proxy" "main" {
  name                   = aws_db_instance.test.db_name
  debug_logging          = false
  engine_family          = "POSTGRESQL"
  idle_client_timeout    = 1800
  require_tls            = true
  role_arn               = aws_iam_role.proxy.arn
  vpc_security_group_ids = []
  vpc_subnet_ids         = data.aws_subnets.all.ids

  auth {
    auth_scheme = "SECRETS"
    description = "Secrets through IAM Authentication"
    iam_auth    = "REQUIRED"
    secret_arn  = aws_secretsmanager_secret.test.arn
  }
}

resource "aws_db_proxy_default_target_group" "main" {
  db_proxy_name = aws_db_proxy.main.name

  connection_pool_config {
    connection_borrow_timeout    = 120
    max_connections_percent      = 100
    max_idle_connections_percent = 50
    session_pinning_filters      = ["EXCLUDE_VARIABLE_SETS"]
  }
}

resource "aws_db_proxy_target" "main" {
  db_instance_identifier = aws_db_instance.test.identifier
  db_proxy_name          = aws_db_proxy.main.name
  target_group_name      = aws_db_proxy_default_target_group.main.name
}

Expectation

It would be exceptional if I could create an aws_db_proxy_default_target_group and aws_db_proxy_target with Terraform using Moto to mock AWS for testing purposes for code utilizing these resources. Thanks again!

Current Setup

A very basic docker-compose.yml file:

  moto-server:
    image: motoserver/moto:latest
    ports:
      - 5000:5000
    environment:
      - MOTO_IAM_LOAD_MANAGED_POLICIES=true