FAQs on AWS Cloud Auto Scaling
Q: What is AWS Cloud Auto Scaling?
A: AWS Cloud Auto Scaling allows you to automatically scale your AWS resources based on demand. It helps maintain application availability and performance, while optimizing costs.
Q: How does AWS Cloud Auto Scaling work?
A: AWS Cloud Auto Scaling monitors your applications and automatically adjusts capacity to maintain steady, predictable performance at the lowest possible cost.
Q: What resources can I auto scale with AWS Cloud Auto Scaling?
A: You can auto scale EC2 instances, Amazon ECS tasks, Amazon DynamoDB tables and indexes, and more.
Q: How do I configure AWS Cloud Auto Scaling?
A: You can configure auto scaling using the AWS Management Console, AWS CLI, or AWS SDKs.
Q: What metrics can I use for auto scaling?
A: You can use various metrics such as CPU utilization, network traffic, request count, and custom metrics for auto scaling.
Q: Can I define custom scaling policies?
A: Yes, you can define custom scaling policies based on your specific requirements.
Q: Is there a way to manually trigger scaling actions?
A: Yes, you can manually trigger scaling actions using the AWS Management Console, AWS CLI, or AWS SDKs.
Q: How does AWS Cloud Auto Scaling handle scaling events?
A: AWS Cloud Auto Scaling handles scaling events by launching or terminating instances based on the defined policies and rules.
Q: Can I integrate AWS Cloud Auto Scaling with other AWS services?
A: Yes, AWS Cloud Auto Scaling can be integrated with other AWS services such as Amazon CloudWatch for monitoring and AWS Identity and Access Management (IAM) for access control.
Q: Is there an API for AWS Cloud Auto Scaling?
A: Yes, AWS Cloud Auto Scaling provides APIs for programmatically managing auto scaling resources.
Example Code:
Here's a simple example of how you can use the AWS CLI to configure auto scaling for EC2 instances based on CPU utilization:
# Create a launch configuration
aws autoscaling create-launch-configuration \
--launch-configuration-name my-launch-config \
--image-id ami-12345678 \
--instance-type t2.micro \
--key-name my-key-pair \
--security-groups my-security-group \
--user-data file://userdata.sh
# Create an auto scaling group
aws autoscaling create-auto-scaling-group \
--auto-scaling-group-name my-auto-scaling-group \
--launch-configuration-name my-launch-config \
--min-size 2 \
--max-size 5 \
--desired-capacity 2 \
--availability-zones us-east-1a us-east-1b \
--default-cooldown 300 \
--health-check-type EC2 \
--health-check-grace-period 300
# Configure auto scaling policies
aws autoscaling put-scaling-policy \
--auto-scaling-group-name my-auto-scaling-group \
--policy-name scale-out \
--scaling-adjustment 1 \
--adjustment-type ChangeInCapacity
aws autoscaling put-scaling-policy \
--auto-scaling-group-name my-auto-scaling-group \
--policy-name scale-in \
--scaling-adjustment -1 \
--adjustment-type ChangeInCapacity
# Attach scaling policies to CloudWatch alarms
aws cloudwatch put-metric-alarm \
--alarm-name CPUHigh \
--alarm-description "Alarm when CPU usage is high" \
--metric-name CPUUtilization \
--namespace AWS/EC2 \
--statistic Average \
--period 300 \
--threshold 70 \
--comparison-operator GreaterThanOrEqualToThreshold \
--evaluation-periods 2 \
--dimensions "Name=AutoScalingGroupName,Value=my-auto-scaling-group" \
--alarm-actions arn:aws:autoscaling:us-east-1:123456789012:scalingPolicy:abc123ab-cdef-1111-a123-12345EXAMPLE:autoScalingGroupName/my-auto-scaling-group:policyName/scale-out
aws cloudwatch put-metric-alarm \
--alarm-name CPULow \
--alarm-description "Alarm when CPU usage is low" \
--metric-name CPUUtilization \
--namespace AWS/EC2 \
--statistic Average \
--period 300 \
--threshold 20 \
--comparison-operator LessThanOrEqualToThreshold \
--evaluation-periods 2 \
--dimensions "Name=AutoScalingGroupName,Value=my-auto-scaling-group" \
--alarm-actions arn:aws:autoscaling:us-east-1:123456789012:scalingPolicy:abc123ab-cdef-1111-a123-12345EXAMPLE:autoScalingGroupName/my-auto-scaling-group:policyName/scale-in
This example creates a launch configuration, an auto scaling group, defines scaling policies, and attaches them to CloudWatch alarms based on CPU utilization. Adjust the parameters according to your requirements.
Important Interview Questions and Answers on AWS Cloud Auto Scaling
Q: What is AWS Auto Scaling?
AWS Auto Scaling automatically adjusts the number of instances in a group, based on the policies you define. It ensures that you have the correct number of instances to handle the load for your application.
Q: Explain the components of AWS Auto Scaling.
AWS Auto Scaling consists of the following components:
- Auto Scaling groups
- Launch configurations
- Auto Scaling policies
- Scaling plans (for predictive scaling)
Q: How do you create an Auto Scaling group using AWS CLI?
Here is the code.
aws autoscaling create-auto-scaling-group --auto-scaling-group-name my-asg --launch-configuration-name my-launch-config --min-size 1 --max-size 10 --desired-capacity 2 --availability-zones us-west-2a us-west-2b us-west-2c
Q: What is a Launch Configuration in Auto Scaling?
A launch configuration is a template that an Auto Scaling group uses to launch EC2 instances. It specifies the instance type, AMI, key pair, security groups, and block device mapping.
Q: How can you scale out an Auto Scaling group based on CPU utilization?
You can create a scaling policy that triggers scaling out (adding more instances) when the CPU utilization exceeds a certain threshold. For example, in AWS CLI:
aws autoscaling put-scaling-policy --auto-scaling-group-name my-asg --policy-name scale-out-policy --scaling-adjustment 1 --adjustment-type ChangeInCapacity --cooldown 300
Q: How does AWS Auto Scaling respond to an instance failure?
AWS Auto Scaling continuously monitors the health of instances in an Auto Scaling group. If an instance fails, Auto Scaling replaces it automatically, ensuring the desired capacity is maintained.
Q: Explain the difference between scaling out and scaling in in AWS Auto Scaling.
Scaling out involves adding more instances to the Auto Scaling group to handle increased load, while scaling in involves removing instances from the group to reduce costs or due to decreased demand.
Q: How do you configure scheduled scaling in AWS Auto Scaling?
You can configure scheduled scaling by creating scheduled actions. For example, to scale out every weekday at 9:00 AM:
aws autoscaling put-scheduled-update-group-action --auto-scaling-group-name my-asg --scheduled-action-name scale-out-weekdays --min-size 2 --desired-capacity 3 --max-size 10 --recurrence "0 9 * * MON-FRI"
