MultiCloud Classroom notes 30/Jul/2025

AWS EC2 instance creation.

• Factors involved:
  • Instance type
  • AMI
  • Network (VPC)
    • subnet (AZ)
    • public ip (optional)
  • Storage:
    • Disk (EBS Volume)
  • Permissions for ec2 (IAM Role)
  • Cloud-init or UserData
• The Root EBS Volume (volume with os) will be from a different physical server to the physical server chosen to create a ec2 instance.
• Cloud-init or UserData is a script or configuration which is execute only once during creation.
  
• Billing by state

lets create an ec2 instance with a user data to install apache server

• Launch ec2
  • select ami
  • select instance type (free tier eligible t2.micro/t3.micro)
  • select network
    • az
    • security group
  • Expand Advanced Details
    • Userdata
      
      
      
• UserData is executed only once during creation.
• The disk is attached to EC2 instance
  
• For this ec2 which we have created on-demand we are paying for
  • ec2 instance (hourly billing)
  • ebs volume
  • public ip address (dynamic)
• In on-demand when we stop the instance
  • ec2 instance billing stops
  • public ip address billing stops
  • ebs volume billing continues.
• Troubleshooting scenario:
  • If my userdata is wrong aws will not alert, to check the status of execution login into ec2 and look for /var/log/cloud-init.log and /var/log/cloud-init-output.log

Resizing the ec2 instances

• AWS allows to resize instances only is ec2 is in stopped state.
• in the below image the ec2 instance is in running state
  
• Resize (Vertical scaling)