Bus tracker service using MQTT broker

Description

Simple HTTP web service which processes telemetries from MQTT server mqtt.hsl.fi written in Go
The service stores the telemetries from the MQTT server and enables REST endpoints to browse through them via pagination.
It also enables endpoint to get the list of the nearest bus telemetries for given position.

See how to run the service.

Assumptions

Prior to building the service I had made the following assumptions.

• Web service should store all the telemetries from the subscription
• User is able to provide current location in form of latitude and longitude
• Web service would be used only in the same timezone

Technologies used

• Go
• GORM - ORM to handle database tables in Go (Automigrations enabled)
• Docker
• Postgres

How to run the service via docker-compose

The web service can be started as a docker container specified by docker-compose.yml file
To run the web service via the docker-compose you are going to need .env file with the following variables.

Environmental variables

Database

• DB_HOST - host address for the database
  Note: has to be name of the database service in docker-compose if docker is used
• DB_PORT - port the database is going to run on
• DB_USER - database user
• DB_PASSWORD - password for the user
• DB_NAME - name of the database

HTTP server

• HTTP_URL - host address for the http server
  Note: has to be "0.0.0.0" for the docker environment runtime. Can be changed if docker not used
• HTTP_PORT - port that the http server will be exposed on

Example .env configuration using docker-compose

# database connection
DB_HOST=telemetry-database
DB_PORT=5432
DB_USER=admin
DB_PASSWORD=strongPw
DB_NAME=telemetries

# HTTP server
HTTP_URL=0.0.0.0
HTTP_PORT=3000

To build the container run following command: docker-compose up -d --build

REST endpoints

Get telemetries

GET <host>:<port>/api/v1/telemetries
GET <host>:<port>/api/v1/telemetries?pageSize=20&page=1

Query parameters

Name	Required	Default value	Description
pageSize	false	20	number of telemetries per page
page	false	1	number of the current page

Get nearest buses

GET <host>:<port>/api/v1/buses/nearest?lat=60.205183&lon=25.145534

Query parameters

Name	Required	Default value	Description
lat	true	None	latitude location of the user
lon	false	None	longitude location of the user

Testing

I have also added a new unit tests to test the most crutial parts of the application - calculating the distance and parsers. The tests run automatically upon Dockefile build. You can also run them via terminal by this command. go test ./..a