AWS EC2 Basics

  • Basic compute solution for AWS. runtimes, OS’s
  • IAAS, gives you access to instances. you manage from the OS upwards
  • Private service by default
  • Uses VPC networking
  • AZ resilient. Instance fails if AZ fails
  • Can use local on-host storage, or Elastic Block Store (Network storage)
  • EC2 has a soft limit of 20 instances per region

Instance lifecycle

  • Running - using CPU, memory, network, & storage
  • Stopped - no CPU, memory, or network resources being used. Only storage
  • Terminated - can’t reverse this.
  • can go from running to stopped & vice versa

Instance types

  • On demand
  • Reserved - these have a time commitment. gives 30-70% discount. Various payment options - no upfront, all upfront, partial upfront
  • Spot - cheap, meant for short lived instances, few hours to a few days. they use bid pricing
  • Dedicated - not sharing memory/cpu

Amazon Machine Image (AMI)

Connecting to EC2

  • Windows uses RDP - Port 3389
  • Linux uses SSH - Port 22 - using key pairs

Auto scaling groups

  • They use launch configurations, these specify the usual EC2 launch stuff.

    • AMI + instance type
    • EC2 user data
    • EBS volumes
    • Security Groups
    • SSH keypair
  • ASG is usually put behind a load balancer

  • Can scale based on:

    • cloudwatch alarms
    • target average CPU usage
    • number of requests on the ELB per instance
    • average network in
    • average network out
    • custom metric, such as number of users connected to application


  • EFS - file level storage service, that can provide a shared file system
  • EBS - virtual hard disk. 1 EC2 -> 1 EBS
  • EFS vs EBS
  • Elasticache - managed caching service for Memcached & redis