Yoyo Wallet DevOps Interview Test

Background

Yoyo Wallet is a building a microservices-based platform.

As a DevOps engineer, you are tasked with improving the engineering efficiency by producing automation tools that provision services in an efficient, predictable and reproducible way.

We use HTTPie in our examples for clarity.

Architecture Overview

                      +-------------------------------------------+
                      |                                           |
                      |             Redis Message Queue           |
                      |                                           |
                      +--------^--------------------------+-------+
                               |                          |
                              (4)                        (6)
                               |                          |
+------------+       +---------+---------+      +---------v--------+
|            |       |                   |      |                  |
|  Auth API  |       |  Transaction API  |      |  Loyalty Worker  | (*n)
|            |       |                   |      |                  |
+--^------+--+       +---^-----------+---+      +------------------+
   |      |              |           |
  (1)    (2)            (3)         (5)
   |      |              |           |
+--+------v--------------+-----------v----+
|                                         |
|                Customer                 |
|                                         |
+-----------------------------------------+

There are 3 distinct services:

• Auth API - Creates authentication tokens to valid users.
• Transaction API - Processes transaction requests.
• Loyalty Worker - Processes loyalty from transactions.

A transaction flow is as follows:

1. A customer authenticates with the Auth API by providing a valid username and password.
2. An authentication token that is valid for 30 seconds is returned.
3. Use this authentication token to make a transaction request to the Transaction API.
4. The Transaction API submits the transaction to a message queue for further background processing.
5. A successful response is returned.
6. Meanwhile, a Loyalty Worker processes the transaction from the message queue by awarding stamps and vouchers as appropriate.

We use environment variables to configure a service.

Your task

• Read the documentation for each service. Run and test them to make sure they work as expected.
• Once you're familiar with the services, use your preferred tools to automate provisioning of a local development environment.
• Be sure to include external dependencies like Redis and configuration management.
• In order for a microservices-based architecture to work best, implement a HTTP router in front of the services that routes requests to the correct service. A popular solution is path-based routing:
  • http://platform/authentication/* → http://authentication-api/*
  • http://platform/transactions/* → http://transactions-api/*
• Make your automation available on a public GitHub repository with a README on how to get things started.

Don't worry too much about making this production ready. We may discuss production considerations with you later on.

Bonus (Optional)

• Containerise services.
• Apply the Twelve Factor App methodology.