Concepts
AWS Auto Scaling monitors your applications and automatically adjusts capacity to maintain steady, predictable performance at the lowest possible cost. It can be applied to various resources such as EC2 instances, ECS tasks, DynamoDB tables, and RDS databases.
Creating an Auto Scaling Plan
Step 1: Choose the Service to Scale
Start by selecting the AWS service that you want to scale. AWS Auto Scaling supports Amazon EC2 instances, Amazon ECS services, Amazon EC2 Spot Fleets, Amazon RDS databases, Amazon DynamoDB tables and indexes, and Amazon Aurora Replicas.
Step 2: Define Scaling Policies
Scaling policies determine when and how to scale your resources. There are two main types of scaling policies:
- Target tracking scaling: Scale based on a target value for a specific CloudWatch metric.
- Step scaling: Scale based on a set of scaling adjustments that change based on the size of the alarm breach.
| Scaling Type | Description |
|---|---|
| Target Tracking | Adjusts the number of instances automatically to maintain the target metric. |
| Step Scaling | Increases or decreases the number of instances in steps, based on the policy’s defined rules. |
Step 3: Create Auto Scaling Groups (for EC2)
For Amazon EC2, an Auto Scaling group contains a collection of EC2 instances that share similar characteristics and are treated as a logical grouping for the purposes of Auto Scaling and management.
To create an EC2 Auto Scaling group, you need to:
- Specify a launch configuration or launch template, which includes the instance type, AMI, key pair, security groups, and other configuration settings.
- Define minimum, maximum, and desired capacity of instances that your group should maintain.
- Define network and subnet configurations for your EC2 instances.
- Set up autoscaling policies that will trigger scaling actions.
<shell>
aws autoscaling create-auto-scaling-group –auto-scaling-group-name my-asg \
–launch-template LaunchTemplateName=my-launch-template,Version=$Latest \
–min-size 1 –max-size 5 –desired-capacity 3 \
–vpc-zone-identifier subnet-1234abcd,subnet-5678efgh
</shell>
Step 4: Set Up Amazon CloudWatch Alarms
Amazon CloudWatch alarms monitor your system’s health and performance. For Auto Scaling, alarms can notify you when certain thresholds are breached and trigger scaling actions based on those alarms.
<shell>
aws cloudwatch put-metric-alarm –alarm-name add-instances \
–metric-name CPUUtilization –namespace AWS/EC2 \
–statistic Average –period 300 –threshold 80 \
–comparison-operator GreaterThanOrEqualToThreshold \
–dimensions “Name=AutoScalingGroupName,Value=my-asg” \
–evaluation-periods 2 –alarm-actions arn-of-the-auto-scaling-policy
</shell>
Maintaining an Auto Scaling Plan
Evaluating Scaling Activities
Regularly review the scaling activities to ensure that the scaling policies are functioning as expected. Check metrics and logs to diagnose any issues or inconsistencies in scaling behavior.
Adjust Scaling Policies
Review and adjust your scaling policies based on changing requirements or trends in workload. For example, if your applications have a predictable traffic pattern, you might want to schedule scaling actions ahead of time.
Perform Regular Audits
Perform regular audits of your Auto Scaling groups and configurations. This will help ensure that you aren’t running underutilized or overprovisioned resources, which could affect performance and cost.
Test Your Setup
Conduct regular tests on your Auto Scaling setup to ensure that it can handle failure scenarios and that the system scales correctly under different load conditions.
Keep Up with AWS Best Practices
AWS frequently updates its services with new features and best practices. Stay informed about these changes to optimize your Auto Scaling plans.
In conclusion, creating and maintaining an AWS Auto Scaling plan involves thoughtful configuration of scaling policies and groups, monitoring system performance with CloudWatch alarms, and regular adjustments and audits to align with your application’s needs. Effectively managing your Auto Scaling configurations can ensure high availability, fault tolerance, and cost efficiency in your AWS environment.
Answer the Questions in Comment Section
True or False: AWS Auto Scaling can automatically adjust only EC2 instances.
False
AWS Auto Scaling can manage scaling for multiple resources such as Amazon EC2 instances, Amazon ECS tasks, Amazon DynamoDB tables, and indexes, as well as Amazon Aurora Replicas.
Which AWS service helps in automatically scaling your AWS resources?
- A) AWS Lambda
- B) AWS Auto Scaling
- C) AWS Elastic Beanstalk
- D) Amazon CloudFront
B) AWS Auto Scaling
AWS Auto Scaling is specifically designed to automatically scale your AWS resources.
True or False: You must manually define the scaling policies for your Auto Scaling group.
False
While you have the option to manually define scaling policies, AWS Auto Scaling can automatically create target tracking scaling policies based on your selected optimization strategy.
Which of the following is not a scaling policy supported by AWS Auto Scaling?
- A) Target Tracking Scaling
- B) Step Scaling
- C) Manual Scaling
- D) Predictive Scaling
C) Manual Scaling
Manual Scaling is not considered a scaling policy; rather it refers to the manual adjustment of capacity by the user.
True or False: Scheduled scaling allows you to set a specific start and end time for scaling actions.
True
Scheduled scaling is a feature of AWS Auto Scaling that allows you to scale your application in response to predictable load changes at specific times.
When creating an Auto Scaling plan, which of the following metrics cannot be used as a predefined metric for target tracking scaling policies?
- A) Average CPU utilization
- B) Disk read operations
- C) Request count per target
- D) Memory utilization
D) Memory utilization
Memory utilization is not a predefined metric for EC2 instances provided directly by Amazon CloudWatch and, therefore, cannot be used without custom metrics.
True or False: To use AWS Auto Scaling, you need to have an existing Elastic Load Balancer.
False
While AWS Auto Scaling can work seamlessly with Elastic Load Balancers to distribute traffic, it is not a prerequisite to use AWS Auto Scaling.
When configuring Auto Scaling, what is the purpose of an instance warm-up time?
- A) The time taken to launch a new instance
- B) The time to deregister an instance from the load balancer
- C) The time to attach EBS volumes to an instance
- D) The time needed for a new instance to initialize and start receiving traffic
D) The time needed for a new instance to initialize and start receiving traffic
Instance warm-up time is the time AWS Auto Scaling waits before considering the instance as a contributor to the aggregate metrics of the Auto Scaling group.
Which of the following statements is true about the cooldown period in AWS Auto Scaling?
- A) The cooldown period only applies to scale-out activities.
- B) The cooldown period is a timeframe during which new scaling activities can be initiated despite existing scaling activities.
- C) The cooldown period prevents the Auto Scaling group from launching or terminating additional instances.
- D) The cooldown period is the default waiting time between two scheduled scaling actions.
C) The cooldown period prevents the Auto Scaling group from launching or terminating additional instances.
The cooldown period is designed to prevent the Auto Scaling group from repeatedly launching or terminating instances before the effects of previous activities are visible.
True or False: It is possible to scale out your EC2 instances based on a custom CloudWatch metric.
True
AWS Auto Scaling supports custom CloudWatch metrics, which means you can scale out or in based on the specified custom metric conditions.
True or False: Auto Scaling Groups work only within one AWS Availability Zone.
False
Auto Scaling Groups can span multiple Availability Zones within the same region to ensure high availability of your application.
In AWS Auto Scaling, what is the main functionality of the Health Check?
- A) To monitor and log the Auto Scaling event history
- B) To check the CPU utilization of the EC2 instances
- C) To determine the operational health of the instances in your Auto Scaling group
- D) To verify the network connectivity between instances
C) To determine the operational health of the instances in your Auto Scaling group
Health checks are used to determine the operational health of the instances so that the Auto Scaling group can replace any instance that is deemed unhealthy.
Thanks for the detailed guide on creating AWS Auto Scaling plans. It was really helpful for my exam preparation!
Can someone explain the significance of scaling policies while configuring auto scaling?
I found the scenario-based examples very insightful. Helped a lot in understanding real-world applications.
The blog post missed some advanced configurations. More details on lifecycle hooks would have been beneficial.
Good overview of auto scaling for the SOA-C02 exam.
Does anyone know if there’s a difference between dynamic scaling and predictive scaling?
Can I use AWS Auto Scaling for both EC2 instances and ECS tasks?
Really great content! Helped clear up a lot of confusion I had.