AWS Classroom Series – 12/Aug/2020

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 Preview Preview Preview Preview Preview
  • Retrieving user data using instance metadata: Preview
  • modifying user data Preview Preview
  • 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. Preview

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