以下の条件を満たすことが必要
- IAM role: policy AmazonSSMManagedInstanceCore とAmazonSSMPatchAssociation を追加
- session manager agent install
- confirm the status: sudo systemctl status amazon-ssm-agent
- 以下のどちらか
3-1. internet accessできること:public ip + internet gateway or NAT
3-2. VPC endpoint( ssm, ssmmessages)を設定 - try rebooting the EC2 instance