AWS Autoscaling basics:

aws-autoscaling

  • Auto scaling makes our environment has desired capacity of EC2 isntances when it is needed.
  • Autoscale supports only horizontal scaling
  • If auto scaling finds unhealthy instances it is replaced with new instances by terminating the old instance.
  • Auto scaling service is free. How ever instances launched by auto scaling is chargeable.
  • Auto Scaling Group:
  • 1. It is a group of EC2 instances which participates in the auto scaling. This group contains Minimum:  Minimum number of isntances this group must contain always. Maximum: Maximum number of isntances that can participate in auto scaling. Desired: Is decided at runtime, based on the scaling policies
  • Note: We can use auto scaling with fixed group size
  • Launch Configuration: It is a template used by auto scaling for launching new isntances
  • Launch configuration contains:
  • 1. AMI
  • 2. Instance Type
  • 3. EBS volume
  • 4. Security Group
  • 5. IAM role
  • 6. SSH key pair.
  • Note: We cannot update launch configuration, we only can configure new one and attach to Auto scaling group