Tag Archive for: Elastic Load Balancer

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Designing a Highly Available Web App Infrastructure

This activity starts with an app running on a single EC2 instance in a single availability zone. Then I make it highly available by cloning it and deploying it in an Auto Scaling group behind an Elastic Load Balancer that spans two availability zones.

  • Create an image of an existing Amazon EC2 instance and use it to launch new instances.
  • Expand an Amazon VPC to additional Availability Zones.
  • Create VPC Subnets and Route Tables.
  • Create an AWS NAT Gateway.
  • Create a Load Balancer.
  • Create an Auto Scaling group.

I have a starting state VPC in which I build out a reference app server. Then I build up the primitives towards high availability.

Setting Up  The  Starting State VPC

The VPC will have a CIDR block of 10.200.0.0/20 giving us an IPv4 range between 10.200.0.0 and 10.200.15.255 (Not all are usable as AWS reserves some)

Subnets

 

The diagram below highlights the starting state of the VPC.