Replica counts

scaleit
The purpose of this exercise is to write an auto-scaler that manipulates the
number of replicas of a separate application based on CPU utilization metrics.
As your auto-scaler changes the replica count, CPU utilization will be impacted
accordingly.
company has provided such an application that has the following characteristics:
* it starts on a user defined port (given by the --port flag) defaulting to 8123
* the JSON/REST API allows you to monitor the application’s emulated CPU
usage and change the number of replicas * its APIs occasionally return errors
to mimic real life
The reported CPU usage will simulate a real application and rise and fall over
time. At the same time, increasing the number of replicas will make the CPU
usage go down and vice versa.
Your Challenge
Write an application that uses the API described below to automatically adjust
the number of replicas to keep the average CPU usage reported to average 0.80
(80%).
Please write your application in one of the following languages: Python, Go,
Ruby, Java, TypeScript/JavaScript, or C/C++
What We’re Looking For

Your submission will be evaluated based on the following criteria: * clean, read-
able, testable, performant and well-documented code * demonstrated knowledge

of software engineering best practices in the programming language of your
choice * correctness and bug-free code
You should be thorough, but feel free to simply document where you would do
things differently in a real production environment rather than an exercise.
We expect that this exercise will take roughly 60 to 90 minutes.
The API
The following describes the REST API implemented by the sample application.
Current Status
The /app/status API expects an HTTP GET request with an Accept header
with a value of application/json. It, as you might expect, returns a JSON
representation of the current app status that looks like this:
{
"cpu": {

1

"highPriority": 0.68
},
"replicas": 10
}
CPU utilization is returned as a float between 0 and 1. Replicas is an integer
greater than or equal to 1.
Updating the Replica Count
The /app/replicas API expects an HTTP PUT request with a Content-Type
header with a value of application/json. The body of the request should
contain JSON in the following format.
{
"replicas": 11
}
The replicas key should have an integer value greater than one. Invalid values
will return HTTP 400 Bad Request.