This is am example app. My goal was to create a concurrent? small and fast JSON API app. Requirements:

• API calls should be faster than 100ms after data seeding (see Data Seed)
• DB = PostgreSQL
• It’s allowed to use any gems and ORMs
• Don’t use RoR
• It’s allowed to use DB capabilities to speed up responses
• Code should be clean, e.g. don’t use generators
• Specs are required

There are 3 models – User (fields: login), Post (fields: title, content, author ip address) and Rating (fields: value(1..5)). Rating belongs to Post, Post belongs to User.

Params: title, content, author ip, author login

Behaviour: Create post. Create user if not exists

Response: 200 – created post attributes, 422 – in case of error

POST http://127.0.0.1:9292/api/v1/posts?login=<user>&title=<title>&ip=<ip>&content=<content>

Params: post id, rating

Behaviour: post has many ratings

Important: action should work correctly on a concurrent update of the same post

Response: 200 – average post rating, 422 – in case of error

PUT http://localhost:9292/api/v1/posts/<post_id>?rating=<rating>

Params: number of posts to return (optional)

Behaviour: Collection of posts with their attributes should be returned

Response: 200 – N posts with their attributes

GET http://localhost:9292/api/v1/posts?count=<count>

Params: user logins

Behaviour: Get all user’s IP addresses from his posts. It should be possible to get some users simultaneously

Response: 200 – users and their IP addresses

GET http://localhost:9292/api/v1/users/ip?logins=<login1>%20<login2>

db/seed.db file should be created. Import data to the DB using JSON API – start server and use API endpoints.

DB should be filled with:

• 100 uniq users
• 50 uniq IP addresses
• 200k posts

This was my first non-Rails API app so I decided to create an app from scratch using something extremely light and fast.
I should have used Roda or Hanami but my decision was to try something experimental 🙂
So my choice for this test task is Hanami::API.

Actually I’ve benchmarked requests/second for Hanami::API, Hanami::Router and Roda on ruby 2.7.0 and the winner was Hanami::Router. Roda was very close to it.
Anyway I would prefer Hanami or Roda for production.

Install gems:

bundle install

Start Postgres server:

docker-compose up -d

Prepare database:

bundle exec rake db:create RACK_ENV=production
bundle exec rake db:migrate RACK_ENV=production

Start server:

bundle exec bin/rackup -q -E production -o 127.0.0.1

Start data seed:

bundle exec rake db:seed RACK_ENV=production

bundle exec rake db:create RACK_ENV=test
bundle exec rake db:migrate RACK_ENV=test
bundle exec rspec