[AWS - DA] Elastic Load Balancer

• "warm-up" for LB to boot faster
• 503 error for capacity or not registered target

 

• Support HTTP redirects to HTTPS at ALB level

• ALB works with ECS

 

 

• NLB has one static IP per AZ
• Extreme performance TCP, UDP traffic

 

Load Balancer Stickiness

• It is possible to implement stickiness so that the same clinet is always redirected to the same instance behind a load balancer.
• This works for Classic Load Balancers & Application Load Balacners
• The "Cookie" used for stickiness has an expiration date you control
• Use Case: make sure the user doesn't lose his session data
• Eanbling stickiness may bring imbalance to the load over the backend EC2 instances

For Application Load Balancer, Stickness is at Target Group settings:

 

 

Connection Draining

Enabling connection draining feature in a load balancer makes sure that any back-end instances you have deregistered will complete requests in progress before the deregistration process starts. Also, if a back-end instance fails to keep up with the recommended health checks, then the load balancer does not send any new requests to the unhealthy instance. Although it will still allow existing requests to complete.

AWS ELB connection draining prevents breaking open network connections while taking an instance out of service, updating its software, or replacing it with a fresh instance that contains updated software.