elastic beanstalk connecting with rds

[israelariel]

Hello. I am new with terraform. Can you provide an example creating a elb env with a rds? I am using your modules for do that.
I create a vpc, an mysql database and then create the application and environment, adding the security group to the allowed_security_groups field in the env.
I have to add attributes, because the rds and elb env was creating the same security group.
The code create all the resources, but I having problem that ec2 Instance can not connect to the DB.

Here is the code:

provider "aws" {
profile = "classlolaws"
region = var.region
}

module "vpc" {
source = "git::https://github.com/cloudposse/terraform-aws-vpc.git?ref=tags/0.7.0"
namespace = var.namespace
stage = var.stage
name = var.name
cidr_block = "172.16.0.0/16"
}

module "subnets" {
source = "git::https://github.com/cloudposse/terraform-aws-dynamic-subnets.git?ref=tags/0.16.0"
availability_zones = var.availability_zones
namespace = var.namespace
stage = var.stage
name = var.name
vpc_id = module.vpc.vpc_id
igw_id = module.vpc.igw_id
cidr_block = module.vpc.vpc_cidr_block
nat_gateway_enabled = true
nat_instance_enabled = false
}

module "rds_instance" {
source = "git::https://github.com/cloudposse/terraform-aws-rds.git?ref=tags/0.19.0"
namespace = var.namespace
stage = var.stage
name = var.name
database_name = var.database_name
database_user = var.database_user
database_password = var.database_password
database_port = var.database_port
multi_az = var.multi_az
attributes = var.rds_attributes
storage_type = var.storage_type
allocated_storage = var.allocated_storage
storage_encrypted = var.storage_encrypted
engine = var.engine
engine_version = var.engine_version
instance_class = var.instance_class
db_parameter_group = var.db_parameter_group
publicly_accessible = var.publicly_accessible
vpc_id = module.vpc.vpc_id
subnet_ids = module.subnets.private_subnet_ids
security_group_ids = [module.vpc.vpc_default_security_group_id]
apply_immediately = var.apply_immediately
dns_zone_id = var.dns_zone_id
db_parameter = [
{
name = "myisam_sort_buffer_size"
value = "1048576"
apply_method = "immediate"
},
{
name = "sort_buffer_size"
value = "2097152"
apply_method = "immediate"
}
]
}

module "elastic_beanstalk_application" {
source = "git::https://github.com/cloudposse/terraform-aws-elastic-beanstalk-application.git?ref=tags/0.5.0"
namespace = var.namespace
stage = var.stage
name = var.name
attributes = var.elb_attributes
tags = var.tags
delimiter = var.delimiter
description = "Test elastic_beanstalk_application"
}

module "elastic_beanstalk_environment" {
source = "git::https://github.com/cloudposse/terraform-aws-elastic-beanstalk-environment.git?ref=tags/0.19.0"
namespace = var.namespace
stage = var.stage
name = var.name
attributes = var.elb_attributes
tags = var.tags
delimiter = var.delimiter
description = var.description
region = var.region
availability_zone_selector = var.availability_zone_selector
dns_zone_id = var.dns_zone_id
dns_subdomain = var.dns_subdomain

wait_for_ready_timeout = var.wait_for_ready_timeout
elastic_beanstalk_application_name = module.elastic_beanstalk_application.elastic_beanstalk_application_name
environment_type = var.environment_type
loadbalancer_type = var.loadbalancer_type
elb_scheme = var.elb_scheme
tier = var.tier
version_label = var.version_label
force_destroy = var.force_destroy

instance_type = var.instance_type
root_volume_size = var.root_volume_size
root_volume_type = var.root_volume_type

autoscale_min = var.autoscale_min
autoscale_max = var.autoscale_max
autoscale_measure_name = var.autoscale_measure_name
autoscale_statistic = var.autoscale_statistic
autoscale_unit = var.autoscale_unit
autoscale_lower_bound = var.autoscale_lower_bound
autoscale_lower_increment = var.autoscale_lower_increment
autoscale_upper_bound = var.autoscale_upper_bound
autoscale_upper_increment = var.autoscale_upper_increment

vpc_id = module.vpc.vpc_id
loadbalancer_subnets = module.subnets.public_subnet_ids
application_subnets = module.subnets.private_subnet_ids
allowed_security_groups = [module.vpc.vpc_default_security_group_id, module.rds_instance.security_group_id]

rolling_update_enabled = var.rolling_update_enabled
rolling_update_type = var.rolling_update_type
updating_min_in_service = var.updating_min_in_service
updating_max_batch = var.updating_max_batch

healthcheck_url = var.healthcheck_url
application_port = var.application_port

solution_stack_name = var.solution_stack_name

additional_settings = var.additional_settings
env_vars = {
"DB_CREATE" = "update"
"HOST_BACKEND" = "http://localhost:8000"
"HOST_FRONTEND" = "http://localhost:3000"
"JDBC_CONNECTION_STRING" = ""
"RDS_DATABASE" = var.database_name
"RDS_HOST" = module.rds_instance.instance_address
"RDS_ENDPOINT" = module.rds_instance.instance_endpoint
"RDS_PORT" = var.database_port
"RDS_USER" = var.database_user
"RDS_PASS" = var.database_password
"RDS_HOST_DNS" = module.rds_instance.hostname
}
}