Apptainer on CentOS Stream 9 Hardened by ThinkCloud

Connection Method Connect via SSH as user 'ec2-user' to the running instance. Use sudo to run commands requiring root access, or switch to root using: sudo su - root

Application Details Check Version: apptainer --version Installation Directory: /usr/bin/apptainer (Binary executable) Configuration Directory: /etc/apptainer/ Configuration File: /etc/apptainer/apptainer.conf (Global configuration file for resource limits and security policies) State Directory: /var/lib/apptainer/

Service Management Note: Apptainer is a Runtime Tool, not a background service daemon. You do not need to "start" or "enable" it using systemctl. How to use: Simply run apptainer commands directly from the terminal when needed. Example: apptainer run docker://alpine

Network Configuration Default Behavior: Apptainer does not listen on any network port by default. It uses the host network stack directly when running containers. External Access: If you run a container that hosts a service (e.g., a web server inside Apptainer), it will bind directly to the host's network interface. Example: If your container listens on Port 80, it opens Port 80 on the host instance. AWS Security Groups: Open the specific ports that your containerized applications require (e.g., 80, 8080, 443) in the AWS Security Group. Please allow SSH port 22 limited IPs for access.