psi/ro-challenge

Code challenge

Building the project

The only local dependency required is Terraform. It can be downloaded and installed from:

https://www.terraform.io/downloads.html

Once Terraform has been installed, you'll need to set appropriate environment variables for your AWS credentials, namely:

$ export AWS_ACCESS_KEY_ID=xxxx
$ export AWS_SECRET_ACCESS_KEY=xxxx

The infrastructure can be built and the Hello app launched by running:

$ ./launch.sh

Upon completion, you'll be given a URL which you can curl to test out the service:

$ curl http://x.x.x.x/hello
$ curl http://x.x.x.x/hello?name=JD

Some final thoughts

By and large, my initial approach held, with the notable exception that I decided that Chef was overkill for the amount of provisioning needed on the EC2 instance once it had been launched. Instead, I opted for a short shell script that is uploaded and executed by Terraform.

Initial approach

After reading the written requirements and asking EJ for clarification on a few points, I've decided to take the following approach, breaking the project into essentially 3 distinct phases.

1. I'll write a simple web service in Ruby, using the Sinatra framework. This service will expose one endpoint, /hello, which will take a single, optional parameter, name. If no name is specified, the service will simply return an HTTP status of 200 with the string "Hello!" in the body. If name is provided, the service will respond with a 200 and "Hello, !" as its response. I will provide a Dockerfile alongside the service to build an image which can then be deployed. The image will expose a single port, Sinatra's default 4567. For simplicity and because I don't have access to EC2 Container Registry for this exercise, I'll cheat just a bit and build this image in the next phase, rather than building and then pushing to a Docker repo.

2. With a deployable image available, my next phase will be to write a Chef cookbook to configure an Ubuntu host with the following objectives:

   • Install and run Docker on the host
   • Build the application image from phase 1
   • Run the application as a Docker container, exposing port 4567 and mapping it to local port 80

3. With configuration management code written to configure a host to serve the application, the final piece will be to actually run the application in EC2. To accomplish this, I'll write Terraform code to do the following:

   • Create a VPC in which to run the EC2 instance (and potentially an ALB)
   • Create a security group for the EC2 instance, allowing inbound traffic from anywhere to port 22 for SSH and port 80 for the web service
   • Create an EC2 instance, bootstrap it with Chef, transfer the configuration management code from phase 2 to the instance, run Chef to configure the instance, and output the public hostname of the EC2 instance where the web service will be reachable.
   • If time allows, I may add an ALB in front of the instance, though it's not required to meet the objectives of this assignment.