Instance metadata and userdata

• Instance metadata is data about your instance
• Instance metadata is divided into categories
  • host name
  • events
  • security groups
• Instance metadata from running instance can be accessed using
  • Instance metadata Service Version 1 (IMDSv1) – a request/response method
  • Instance metadata Service Version 2 (IMDSv2) – a session-oriented method.
• By default both versions work, but you can configure instance metadata option
• To retrieve metadata from running instance use the following URI

http://169.254.169.254/latest/meta-data/

• Refer Here
• User data: is set of commands/data you can provide at instance launch time
• User data can be entered during launch of ec2 instance
• Retrieving user data using instance metadata:
• modifying user data
• In user data you can also specify cloud-init

AWS System Status checks

• Types of Status checks
  • System Status Checks: Checks the AWS system on which instance runs. The physical server on which aws ec2 instance might have some failures such as
    • loss of network connectivity
    • Loss of power
    • Software/Hardware issues on physical server/host
  • Instance Status Checks: Check the software & network configuration of your individual instance. EC2 sends ARP (Address resolution protocol) to the network interface (NIC).
  • The following are problems that can cause instance checks to fail
    • System status fails
    • Exhausted memory
    • Corrupted filesystem
    • Incompatible kernel
    • Incorrect networking or startup configuration.