Service to demonstrate ECS with Fargate.

A simple hello world app with health check written using Go with Gorilla mux for routing requests.

The dockerfile has been built in 2 stages. The first to get dependencies and build the app. The second using a distroless build with only the bare essentials to run the app.

The file can built and ran locally (exposing at port 8080) with:

docker build -t energycost .
docker run -p 8080:8080 -it energycost

Infrastructure has been written using Terraform for ECS on AWS with high availability in mind. The project consists of the following:

• A VPC with a /16 netmask, allowing for a total of 65536 IP addresses.
• Subnets with /24 netmasks, allowing for a total of 256 IP addresses per subnet.
• 3 Public subnets, in 3 AZs.
• 3 Private application subnets, in 3 AZs. These will host all application servers.
• 3 Private database subnets, in 3 AZs. These will host all database servers.
• 1 internet gateway.
• Public route table, with route to the internet gateway. Public subnets are associated with the public route table.
• Public security group. Allow tls/http from anywhere and all egress traffic.
• Private application security group. Allow traffic from the resources associated with the public security group and all egress traffic.
• Default security group. Allow all internal VPC traffic and all egress traffic.
• VPC endpoints associated with the VPC for ECR (dkr and api instance endpoint) and S3 (gateway endpoint). This allows ECS to pull the requested resources from ECR.
• Application Load Balancer in the 3 public subnets, associated with the public security group. ALB has health check configured to for /health, along with a http listener.
• ECR repository to hold the docker image.
• ECS task definition using fargate defined with the minimum compute (256 cpu, 512 memory).
• ECS cluster with single service running the task definition running within the private application subnets and the private application security group.
• Autoscaling scheduled actions: in to 0 in the evening, and out to 1 in the morning.
• Autoscaling target tracking policy to scale in/out to maintain a maximum of 75% cpu utilization.