Terraform : Beanstalk connection with RDS instance - amazon-web-services

Question

I have an error when I build my Beanstalk environment thanks to Terraform. I use Beanstalk with Docker. The error come from the build of Docker Image like we could see thanks to terraform apply error :
Error: creating Elastic Beanstalk Environment (app-dev): waiting for completion: 3 errors occurred:
│ * 2023-02-19 18:36:21.159 +0000 UTC (e-jnwgwcdy7q) : Instance deployment failed. For details, see 'eb-engine.log'.
│ * 2023-02-19 18:36:21.159 +0000 UTC (e-jnwgwcdy7q) : Instance deployment failed to build the Docker image. The deployment failed.
│ * 2023-02-19 18:36:24.538 +0000 UTC (e-jnwgwcdy7q) : [Instance: i-0feeb08c4da8ff1b5] Command failed on instance. Return code: 1 Output: Engine execution has encountered an error..
The custom Docker image contains a Django Rest API where I install my requirements and where I also made migrations inside my RDS instance. The DRF API gets the connection endpoints thanks to environment variables.
Inside it, I provide this Beanstalk stack with application, environment, and application version :
resource "aws_elastic_beanstalk_application" "beanstalk_app" {
  name        = var.project_ref
  description = "Beanstalk application for Django App"
}
resource "aws_elastic_beanstalk_environment" "beanstalk_env" {
  name                = var.project_ref
  application         = aws_elastic_beanstalk_application.beanstalk_app.name
  solution_stack_name = "64bit Amazon Linux 2 v3.5.4 running Docker"
  tier                = "WebServer"
  version_label       = aws_elastic_beanstalk_application_version.beanstalk_app_version.id
  setting {
    namespace = "aws:autoscaling:launchconfiguration"
    name = "IamInstanceProfile"
    value = aws_iam_instance_profile.ec2_eb_profile.name
  }
  # Env vars
  setting {
    namespace = "aws:elasticbeanstalk:application:environment"
    name      = "DB_PORT"
    value     = var.project_port
  }
  setting {
    namespace = "aws:elasticbeanstalk:application:environment"
    name      = "DB_NAME"
    value     = var.project_name
  }
  setting {
    namespace = "aws:elasticbeanstalk:application:environment"
    name      = "DB_USER"
    value     = var.project_db_user
  }
  setting {
    namespace = "aws:elasticbeanstalk:application:environment"
    name      = "DB_PASSWORD"
    value     = var.project_db_pwd
  }
  setting {
    namespace = "aws:elasticbeanstalk:application:environment"
    name      = "DJANDO_ADMIN_PWD"
    value     = var.project_admin_pwd
  }
  # Logs
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs"
    name      = "StreamLogs"
    value     = "true"
  }
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs"
    name      = "RetentionInDays"
    value     = "1"
  }
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs"
    name      = "DeleteOnTerminate"
    value     = "false"
  }
  # Logs health
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs:health"
    name      = "HealthStreamingEnabled"
    value     = "true"
  }
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs:health"
    name      = "DeleteOnTerminate"
    value     = "true"
  }
  setting {
    namespace = "aws:elasticbeanstalk:cloudwatch:logs:health"
    name      = "RetentionInDays"
    value     = "1"
  }
  # Tags
  tags = {
    Name = var.project_ref
    Environment = var.project_env
  }
}
resource "aws_elastic_beanstalk_application_version" "beanstalk_app_version" {
  name        = var.project_ref
  description = "application version created by terraform"
  application = aws_elastic_beanstalk_application.beanstalk_app.id
  bucket      = aws_s3_bucket.s3_bucket_back.id
  key         = aws_s3_object.s3_bucket_back_zip.id
}
resource "aws_iam_instance_profile" "ec2_eb_profile" {
  name = "beanstalk-service-user"
  role = "${aws_iam_role.ec2_eb_role.name}"
  tags = {
    Name = var.project_ref
    Environment = var.project_env
  }
}
resource "aws_iam_role" "ec2_eb_role" {
  name = "beanstalk-service-role"
  assume_role_policy = data.aws_iam_policy_document.instance_assume_role_policy.json
}
I also provide a RDS instance like :
resource "aws_db_instance" "db_instance_project" {
  allocated_storage      = 10
  db_name                = var.project_name
  engine                 = "postgres"
  engine_version         = "13.7"
  instance_class         = "db.t3.micro"
  username               = var.project_db_user
  password               = var.project_db_pwd
  skip_final_snapshot    = true
  vpc_security_group_ids = [aws_default_security_group.security_group.id]
  publicly_accessible    = true
}
The security group called in db_instance was correctly opened on the corresponding port.
The application version called S3 Bucket to fetch a docker-compose.yaml stack inside a zip archive with the code to launch.
To conclude, I wonder if there is a way ton debug the Docker Image build or the Terraform launch build ? My eb-engine.log is empty, and all CloudWatch logs are empty also. Is there another way to read logs ?
Do you think this is an error to contact RDS instance ? I purposely opened the RDS public for testing, but there was no change after.
Thanks for your answer and ideas.
EDIT 20/02/2023 : I also tried to insert database config inside my Beanstalk environment like :
setting {
namespace = "aws:rds:dbinstance"
name = "HasCoupleDatabase"
value = false
}
setting {
namespace = "aws:rds:dbinstance"
name = "DBEngine"
value = "postgres"
}
setting {
namespace = "aws:rds:dbinstance"
name = "DBEngineVersion"
value = "13.7"
}
setting {
namespace = "aws:rds:dbinstance"
name = "DBInstanceClass"
value = "db.t3.micro"
}
setting {
namespace = "aws:rds:dbinstance"
name = "DBUser"
value = var.project_db_user
}
setting {
namespace = "aws:rds:dbinstance"
name = "DBPassword"
value = var.project_db_pwd
}
However, we couldn't defined a DB_NAME with this method. So I tried to created an RDS Instance resource to create my DB. Then, I couldn't insert an RDS_DB_HOST to my Beanstalk settings so I don't understand how I can proceed to connect them together.