Setting up Internet facing load balancer in AWS

AWS ELBAn Internet-facing load balancer takes requests from clients over the Internet and routes them to the back-end instances. To create an Internet-facing load balancer, ensure that your subnets are public subnets. A public subnet has a route to an Internet gateway.

You must ensure that the load balancer can communicate with your back-end instances on both the listener port and the health check port. The security group for your instances must allow traffic in both directions on both ports for each subnet attached to your load balancer. In case you are having multiple ETH interfaces or multiple IP’s configured to a single interface make sure the primary IP is listening for the desired port to be load balanced.

Follow the instructions on AWS ELB documentation. While configuring HTTPS connections make sure to configure your backend https server with the SSL certificate created for your domain. The SSL certificate configured in the ELB for https & the server certificate should match. Make sure to configure a the Ping Path page under health check configuration to a page which is accessible. For instance a index or a welcome page.

Monitoring the ELB to Backend instances :

Some of the metrics we need to look for after configuring the ELB is under the ELB monitoring tab

BackendConnectionErrors

The number of connections that were not successfully established between the load balancer and the registered instances. Because the load balancer retries the connection when there are errors, this count can exceed the request rate

HTTPCode_ELB_XXX

The number of HTTP 5XX & 4XX server error codes generated by the load balancer when the listener is configured to use the HTTP or HTTPS protocol. This does not include any response codes generated by registered instances.

The metric is reported if there are no healthy instances registered to the load balancer, or if the request rate exceeds the capacity of the instances or the load balancer.

HealthyHostCount

The number of healthy instances in each Availability Zone. An instance is considered healthy if it meets the healthy threshold configured for the health checks. If cross-zone load balancing is enabled, the number of healthy instances is calculated across all Availability Zones.

AWS ELN monitoring