aws Auto Scaling, vertical and horizontal scaling, the lifecycle of Auto Scaling

AWS Auto Scaling is a service that automatically scales resources in response to changes in demand, ensuring that you have the right resources available at the right time to handle your application workload.

Auto Scaling can scale your resources both horizontally (adding or removing instances) and vertically (increasing or decreasing the size of instances) based on demand.

Horizontal scaling increases or decreases the number of instances in your Auto Scaling group based on the demand for your application.

For example, during periods of high traffic, Auto Scaling will automatically add more instances to your group to handle the increased load.

Similarly, during periods of low traffic, Auto Scaling will remove instances from your group to reduce costs.

Vertical scaling increases or decreases the size of your instances based on the demand for your application. For example, if your application requires more CPU or memory resources, Auto Scaling can automatically increase the size of your instances to handle the increased workload. Similarly, if the demand for your application decreases, Auto Scaling can decrease the size of your instances to save costs.

The lifecycle of Auto Scaling consists of the following stages:

1. Launch: When an instance is launched, it is automatically added to the Auto Scaling group.
2. Scale Out: As the demand for your application increases, Auto Scaling will add more instances to your group to handle the increased load.
3. Scale In: As the demand for your application decreases, Auto Scaling will remove instances from your group to reduce costs.
4. Terminate: When an instance is terminated, it is removed from the Auto Scaling group.

Auto Scaling can be triggered based on a variety of metrics, including CPU usage, network traffic, and application load.

You can configure Auto Scaling to scale based on a single metric or a combination of metrics.

Overall, AWS Auto Scaling is a powerful tool that can help you optimize the performance and cost of your applications by automatically scaling your resources based on demand.

Whether you need to scale horizontally or vertically, Auto Scaling can help ensure that you have the right resources available at the right time to handle your workload.

AWS cross zone load balancing

Cross-Zone Load Balancing is a feature of the AWS Elastic Load Balancer service that allows the distribution of incoming traffic across instances in multiple Availability Zones (AZs) within a region, rather than just in the same AZ as the load balancer.

It works by distributing the traffic evenly across all registered instances, regardless of which AZ they are located in.

By default, the load balancer distributes incoming traffic only to the instances located in the same AZ as the load balancer.

However, this can lead to uneven distribution of traffic if there are only a few instances in the same AZ as the load balancer or if there is a sudden spike in traffic. Cross-Zone Load Balancing helps to distribute traffic more evenly and improves the overall performance and availability of your applications.

For example, consider a web application that consists of multiple instances running in different AZs within a region.

The load balancer can distribute incoming traffic across all instances, regardless of which AZ they are located in, resulting in a more even distribution of traffic and improved application performance.

To enable Cross-Zone Load Balancing, you simply need to turn on the "Cross-Zone Load Balancing" option in the configuration settings of your Elastic Load Balancer.

Once enabled, the load balancer will distribute incoming traffic across all registered instances, regardless of which AZ they are located in.

Overall, Cross-Zone Load Balancing is an important feature of the Elastic Load Balancer service that helps to improve the performance and availability of your applications by distributing incoming traffic more evenly across all registered instances, regardless of which AZ they are located in.

AWS Load Balancer Architecture

AWS Load Balancer is a highly available and scalable service that distributes incoming traffic to multiple targets (such as EC2 instances, containers, and IP addresses) across one or more Availability Zones (AZs) within a region.

This helps to improve the availability, scalability, and fault tolerance of your applications by ensuring that incoming traffic is evenly distributed and that healthy targets receive traffic.

Here's an example of AWS Load Balancer architecture using an Application Load Balancer (ALB):

Example

In this example, the web application consists of two microservices running on different EC2 instances within two Availability Zones.

The ALB is used to route incoming HTTP/HTTPS requests to the appropriate microservice based on the path of the request.

The architecture consists of the following components:

1. Clients: These are the users who access the web application via a web browser or a mobile app.
2. DNS: The domain name system (DNS) routes incoming requests to the appropriate load balancer based on the domain name.
3. Application Load Balancer: The ALB routes incoming requests to the appropriate microservice based on the path, host, query string, or headers of the request.
4. Target Group: A target group is a collection of targets (such as EC2 instances or containers) that receive traffic from the load balancer based on the configured routing rules.
5. EC2 Instances: The EC2 instances host the microservices that handle incoming requests from the ALB. These instances are registered with the target group and receive traffic based on the routing rules.
6. Availability Zone: An Availability Zone is an isolated location within a region that consists of one or more data centers. The targets are distributed across multiple Availability Zones to improve fault tolerance and scalability.
7. Auto Scaling Group: An Auto Scaling group is used to automatically scale the number of EC2 instances based on the demand to handle incoming traffic.

Overall, the AWS Load Balancer architecture helps to ensure that incoming traffic is evenly distributed across multiple targets, resulting in improved availability, scalability, and fault tolerance.