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ASG SOA

Links: 114 AWS SOA Index

Troubleshooting

  • x number of instances instance(s) are already running. Launching EC2 instance failed.
    • The Auto Scaling group has reached the limit set by the Maximum Capacity parameter.
    • Update your Auto Scaling group by providing a new value for the maximum capacity.
  • Launching EC2 instances is failing:
    • The security group does not exist. SG might have been deleted.
    • The key pair does not exist. The key pair might have been deleted.

CloudWatch Metrics

  • Metrics are collected every 1 minute
  • ASG-level metrics: (opt-in)
    • GroupMinSize, GroupMaxSize, GroupDesiredCapacity
    • GrouplnServicelnstances, GroupPendingInstances, GroupStandbyInstances
    • GroupTerminatingInstances, GroupTotalInstances
  • We should enable metric collection to see these metrics

AWS AutoScaling

AWS Autoscaling is the backbone service of auto scaling for all scalable resources in AWS

Example: ASG, ECS, Aurora, DynamoDB (WCU & RCU)

  • It also has a separate UI.

Scaling plans

  • Dynamic scaling: creates a target tracking scaling policy
    • Optimise for availability: 40% of resource utilisation
    • Balance availability and cost: 50% of resource utilisation
    • Optimise for cost: 70% of resource utilisation
    • Custom => choose own metric and target value
  • Predictive scaling: continuously forecast load and schedule scaling ahead

Questions

You want a small website on EC2 instances under an ASG that has a target size varying between 2 and 10 instances. Your ASG has a policy to scale out when your target CPU Utilization is above 75%. It has been over 3 hours that the CPU Utilization of your ASG is 90% and still, no scaling out actions have taken place. What are the most likely reasons for this?
  • Your ASG is at maximum capacity already.
  • Your ASG Launch process has been suspended.
  • For Amazon EC2 Auto Scaling, there are two primary process types: Launch and Terminate. The Launch process adds a new Amazon EC2 instance to an Auto Scaling group, increasing its capacity. The Terminate process removes an Amazon EC2 instance from the group, decreasing its capacity.
  • If the Launch process is suspended, then your Auto Scaling group does not scale out for alarms or any scheduled actions that occur.

Last updated: 2023-03-22