You specified the 'AWSEBRDSDBInstance' resource in your configuration to create a database instance,
without the corresponding database security group 'AWSEBRDSDBSecurityGroup'. For a better way to add
and configure a database to your environment, use 'eb create --db' or the Elastic Beanstalk console
instead of using a configuration file.

Resources:
    AWSEBRDSDatabase:
        Type: AWS::RDS::DBInstance
        Properties:
            AllocatedStorage: 5
            DBInstanceClass: db.t2.micro
            DBName: phctest
            Engine: postgresql
            EngineVersion: 10.4
            MasterUsername: username
            MasterUserPassword: password