- 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
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