[AWS]Cloud9で何か上に通知メッセージが出ている件

AWS root account login detected We do not recommend using your AWS root account to create or work with environments. Use an IAM user instead. This is an AWS security best practice. For more information, see Setting Up to Use AWS Cloud9

rootユーザでCloud9を使おうとするとなんか出るので、IAMでIAMユーザを作った方がいいらしい。

We recommend the following best practices for using your AWS Cloud9 environment
Use source control and backup your environment frequently. AWS Cloud9 does not perform automatic backups.
Perform regular updates of software on your environment. AWS Cloud9 does not perform automatic updates on your behalf.
Turn on AWS CloudTrail in your AWS account to track activity in your environment. Learn more
Only share your environment with trusted users. Sharing your environment may put your AWS access credentials at risk. Learn more

環境構築時にも、バックアップの必要性や、AWS CloudTrailを使った追跡ログを活用することをお勧めされる。