BGL Take Home Task!!

Basically the application consists of a background task which fetches BTCUSD price from Binance.us every minute in MariaDB, and a RESTFUL API for queries of the followings from the database:

1. Last Price;
2. Price at a Time Point; and
3. Average Price within a Time Range.

Architecture

The application run on two docker containers:

1. Golang App (docker image built based on golang:1.14.2-alpine);
2. MariaDB (mariadb:10.5.1-bionic).

The two containers communicate through the docker network bgl.

Code Organisation

Codes under the following folders focus on different functions:

binance:

Responsible for sending periodical requests to binance API to get the lastest BTCUSD prices, and storing the data into the database.

db:

Responsible for communication with the Database. In this case, it is MariaDB.

helpers:

Contains helper functions such as average value calculations, float64-string interconversions and timestamp formatting.

servers:

Restful API codes that accept http requests and respond to them.

1. router.go: define routes of the API;
2. controllers.go: accept HTTP Requests, determine which functions to call and repond with appropriate HTTP Reponses;
3. responses.go: "bridges" between controllers.go and db.go.

Build

1. Run docker network create bgl to docker network bgl.

2. Run the following command to start the DB container service:

docker run --net=bgl --name test-server_mariadb -p 3306:3306 -e MYSQL_ROOT_PASSWORD=bgl -e MYSQL_DATABASE=bgl -e MYSQL_USER=bgl -e MYSQL_PASSWORD=bgl -e MYSQL_DATABASE=bgl -d mariadb:10.5.1-bionic

3. Get the IP Address of DB container service with docker inspect test-server_mariadb | grep IPAddress

4. In .env, set DB_CONNECT=<IP Address>:3306 with the IP Address obtained in the previous step.

5. In project root, run the following commands to start the application:

docker build -t test-server .
docker run -d --rm --name test-server --net=bgl -p 80:80 test-server

(Alternative) Build with docker-compose

1. In .env, set DB_CONNECT=mariadb.
2. In project root, run the following command to start the application:

docker-compose up -d

Make sure you have docker and docker-compose installed. Give about 30s - 1min for the system to initialize.

Tests

In project root, run the following commands to run the tests:

go get "github.com/stretchr/testify/assert"
go get "github.com/DATA-DOG/go-sqlmock"
go test ./db/... ./helpers/... ./server/...

CURL

1. Last Price

eg. curl http://localhost/lastprice

Example result:

{"lastPrice":"8853.23","time":"2020-05-12 15:54:47 +0800 HKT"}

2. Price at a Time Point

Endpoint: http://localhost/price/{timestamp}

eg. curl http://localhost/price/2020-05-13T15:23:00

Example result:

{"price":"8862.36","time":"2020-05-12 15:54:47 +0800 HKT"}

3. Average Price within a Time Range

Endpoint: http://localost/averagePrice/{from}/{to}

eg. curl http://localhost/averagePrice/2020-05-13T14:23:00/2020-05-13T15:23:00

Example result:

{"avgPrice":"8830.28","timeRange":"2020-05-13T03:23:00 to 2020-05-13T04:23:00"}