If you have high reliability and performance requirements on cloud services, you can use ELB to distribute traffic to different backend ECSs. ELB ensures that only healthy ECSs receive traffic and that services are not interrupted if an ECS is faulty, thereby ensuring cloud service availability.
Achieving Even Better Fault Tolerance for Your Applications
- You can build fault tolerant applications by placing your applications in multiple Availability Zones. To achieve even more fault tolerance with less manual intervention, you can use Elastic Load Balancing. You get improved fault tolerance by placing your compute instances behind an Elastic Load Balancer, as it can automatically balance traffic across multiple instances and multiple Availability Zones and ensure that only healthy instances receive traffic.
Using Elastic Load Balancing in your VPC:
- Elastic Load Balancing makes it easy to create an internet-facing entry point into your VPC or to balance load between tiers of your application within your VPC. You can assign security groups to your ELB to control which ports are open to a list of allowed sources. Because Elastic Load Balancing is attached to your VPC, all of your existing Network Access Control Lists (ACL’s) and Routing Tables continue to provide additional network controls. When you create a load balancer in your VPC, you can specify whether the load balancer is internet-facing (the default) or internal. If you select internal, you do not need to have an internet gateway to reach the load balancer, and the private IP addresses of the load balancer will be used in the load balancer’s DNS record.
Auto Scaling with Elastic Load Balancing:
- Assume that you want to make sure that the number of healthy ECS instances behind an Elastic Load Balancer is never fewer than two. You can use Auto Scaling to set these conditions, and when Auto Scaling detects that a condition has been met, it automatically adds the requisite amount of ECS instances to your Auto Scaling Group. Or, if you want to make sure that you add ECS instances when latency of any one of your ECS instances exceeds 4 seconds over any 15 minute period, you can set that condition, and Auto Scaling will take the appropriate action on your ECS instances — even when running behind an Elastic Load Balancer. Auto Scaling works equally well for scaling ECS instances whether you’re using Elastic Load Balancing or not.
CES with Elastic Load Balancing:
- After you have obtained the ELB service, you can use CES to view the status of monitored objects of the service, without requiring additional plug-ins to be installed. ELB monitoring metric lists the ELB metrics supported by the CES.