ELB & ASG - Elastic Load Balancing & Auto Scaling Groups

ASG Scaling Strategies

- Manual Scaling - Dynamic Scaling - Predictive Scaling

Why would you use a load balancer?

- Spread load across multiple downstream instances - Expose a single point of access (DNS) to your application - Seamlessly handle failures of downstream instances - Do regular health checks to your instances - Provide SSL termination (HTTPS) for your websites - High availability across zones

ALB vs NLB vs GLB

ALB = Application Load Balancer: balances HTTP / HTTPS traffic (layer 7), has HTTP routing features, has static DNS (URL) NLB = Network Load Balancer: balances TCP / UDP traffic (layer 4), used for high performance (e.g., millions of requests per second), has static IP through Elastic IP GLB = Gateway Load Balancer: balances GENEVE protocol on IP Packets (layer 3), routes traffic to firewalls that you manage on EC2 instances, has intrusion detection

How can an ASG provide cost savings?

ASG enables you to run servers at an optimal capacity at all times, so you're only spending what money is required to be spent based on load

Which load balancer is best suited for HTTP / HTTPS load balancing traffic?

Application Load Balancer

What is the main purpose of High Availability in the Cloud?

Application must thrive even in case of a disaster

ASG =

Auto Scaling Group

Elastic Load Balancers (ELB) characteristics

Characteristics of this service include: - Distributes traffic across backend EC2 instances, can be multi-AZ - Supports health checks - 3 types: Application LB for HTTP / HTTPS traffic (layer 7), Network LB for TCP traffic (layer 4), Gateway LB for distributing traffic while simultaneously scaling virtual appliances

Auto Scaling Groups (ASG) characteristics

Characteristics of this service include: - Implement Elasticity for your application, across multiple AZ - Scale EC2 instances based on the demand on your system, replace unhealthy - Integrated with the ELB

What is load balancing?

Distributing a computing or networking workload across multiple systems to avoid congestion and slow performance.

ELB =

Elastic Load Balancer

What is an Auto Scaling Group?

Enables you to automatically scale your servers in, out, up, and / or down to meet changing loads on your server(s) - Ensures a minimum and maximum number of machines are running - Automatically registers new instances to a load balancer - Replaces unhealthy instances

ASG Scaling Strategies: Manual Scaling

Enables you to update the size of an ASG manually

High Availability

Means to run your app / system in at least 2 Availability Zones Run instances for the same app across multi-AZ Goal is to survive a data center loss

Which AWS offered Load Balancer should you use to handle hundreds of thousands of connections with low latency?

Network Load Balancer

Elasticity

Once a system is scalable, _________ means that there will be some "auto-scaling" so that the system can scale based on the load. This is cloud-friendly - pay-per-use, match demand, optimize costs

Regarding ELB, AWS is responsible for

Per the Shared Responsibility Model, _______ is responsible for - Upgrading and maintaining the ELB - Ensuring the ELB is highly available - Providing a few configuration functions

ASG Scaling Strategies: Dynamic Scaling

Responds to changing demand. 3 types: - Simple / Step Scaling - Target Tracking Scaling - Scheduled Scaling

Load balancers are

Servers that forward internet traffic to multiple servers (EC2 instances) downstream

How does Elastic Disaster Recovery work?

Set this service up on your source servers to initiate secure data replication. Your data is replicated to a staging area subnet in your AWS account, in the AWS Region you select. The staging area design reduces costs by using affordable storage and minimal compute resources to maintain ongoing replication. You can perform non-disruptive tests to confirm that implementation is complete. During normal operation, maintain readiness by monitoring replication and periodically performing non-disruptive recovery and failback drills. If you need to recover applications, you can launch recovery instances on AWS within minutes, using the most up-to-date server state or a previous point in time. After your applications are running on AWS, you can choose to keep them there, or you can initiate data replication back to your primary site when the issue is resolved. You can fail back to your primary site whenever you're ready.

Network Load Balancer target type

Target types are IP, Instance, App Load Balancer

Application Load Balancer target type

Target types are IP, Instance, Lambda

4 kinds of load balancers offered by AWS:

These are the different types: 1) Application Load Balancer 2) Network Load Balancer 3) Gateway Load Balancer 4) Classic Load Balancer

Scalability

This is the ability of an application / system to handle greater / smaller loads by adapting to increase / decrease in demand with minimal latency and downtime

Horizontal scaling

This kind of scaling entails - Increasing the number of instances / systems for your application - Implies distributed systems - Common for web applications / modern applications - Scaling in or out

Vertical Scaling

This kind of scaling entails increasing the processing power of individual components. Scaling up or down

Gateway Load Balancer

This load balancer helps you easily deploy, scale, and manage your third-party virtual appliances. It gives you one gateway for distributing traffic across multiple virtual appliances while scaling them up or down, based on demand. This decreases potential points of failure in your network and increases availability. Layer 3 Gateway + Layer 4 Load Balancing

Network Load Balancer

This load balancer operates at the connection level (Layer 4), routing connections to targets (Amazon EC2 instances, microservices, and containers) within Amazon VPC, based on IP protocol data. Ideal for load balancing of both TCP and UDP traffic, this load balancer is capable of handling millions of requests per second while maintaining ultra-low latencies. Optimized to handle sudden and volatile traffic patterns while using a single static IP address per Availability Zone. It is integrated with other popular AWS services such as Auto Scaling, Amazon EC2 Container Service (ECS), Amazon CloudFormation, and AWS Certificate Manager (ACM).

Application Load Balancer

This load balancer operates at the request level (layer 7), routing traffic to targets (EC2 instances, containers, IP addresses, and Lambda functions) based on the content of the request. Ideal for advanced load balancing of HTTP and HTTPS traffic, this load balancer provides advanced request routing targeted at delivery of modern application architectures, including microservices and container-based applications.

Classic Load Balancer

This load balancer provides basic load balancing across multiple Amazon EC2 instances and operates at both the request level and connection level. Classic Load Balancer is intended for applications that are built within the EC2-Classic network. Layer 4 & 7

What is AWS Elastic Load Balancer?

This service automatically distributes incoming application traffic across multiple targets and virtual appliances in one or more Availability Zones (AZs). Costs less to setup your own instance of this but it requires more effort from you for maintenance and integrations

AWS Elastic Disaster Recovery

This service minimizes downtime and data loss with fast, reliable recovery of on-premises and cloud-based applications using affordable storage, minimal compute, and point-in-time recovery.

Auto Scaling Groups can be implemented with load balancers. True or false?

True Auto Scaling Groups define how many servers are running at a time, and a load balancer can be used in conjunction with an ASG

Simple / Step Scaling

Type of Dynamic ASG scaling strategy - Adds / removes units based off need E.g., When a CloudWatch alarm is triggered (e.g., CPU > 70%), then add 2 units E.g., When a CloudWatch alarm is triggered (e.g., CPU < 30%), then remove 1 unit

Predictive Scaling

Type of Dynamic ASG scaling strategy - Uses Machine Learning to predict future traffic ahead of time - Automatically provisions the right number of EC2 instances in advance - Useful when your load has predictable time-based patterns

Target Tracking Scaling

Type of Dynamic ASG scaling strategy Allows you to specify a target CPU, RAM, storage, etc. that the ASG can scale to meet. E.g., I want the average ASG CPU to stay at around 40%

Scheduled Scaling

Type of Dynamic ASG scaling strategy Anticipates a scaling based on known usage patterns. E.g., increase the min. capacity to 10 at 5pm on Fridays

Two kinds of scalability

Vertical and horizontal

When you use Elastic Load Balancing with ______ you can build highly available, fault-tolerant applications which automatically scale capacity up or down based on fluctuations in demand.

When you use Elastic Load Balancing with Auto Scaling, you can build highly available, fault-tolerant applications which automatically scale capacity up or down based on fluctuations in demand.

Which AWS service offers easy horizontal scaling of compute capacity? a) EBS b) AMI c) IAM d) ASG

d) ASG

Which of the following statements is NOT a feature of load balancers? a) Do regular health checks on your instances b) Spread load across multiple downstream instances c) Handle failures of downstream instances d) Back-end autoscaling

d) Back-end autoscaling