The Solution

First, I reviewed the task and tried to define the business logic. I believe that to implement the exploreService, I also need an underlying domain service, which I named the decision module.

In my implementation, I follow a lightweight hexagonal-based architecture, where there are various domain modules in the system, and we can utilize different actors for communication.

The decision domain module is essentially a repository layer that stores the defined entity in the database and performs other operations.

The explore module is responsible for implementing the service definition specified in the proto file (service), as well as matching the generated gRPC code (controller). The explore module does not contain state and is dependent on the decision domain module.

I bootstrapped the project using a starter kit maintained by me and followed the structural recommendations of the starter kit. I wrote more about this here: Github Repo.

Each domain module has a definition file (decision.go, explore.go), a module.go file responsible for exporting providers, and provider files (controller.go, service.go, repository.go) that are responsible for interactions with various actors (db, gRPC).

Notes

The gRPC definition included a pagination token. I implemented this token using the created_at timestamp. This returns the next items in the list in descending order of creation time ((created_at < sqlc.arg('pagination_token')::date OR sqlc.narg('pagination_token') IS NULL)). Since the definition did not include a Limit, I set a default value of 10 in the repository layer.

Test

I have prepared unit tests for each domain module. The unit tests are mocked, for which I used Mockery. I aimed to test the units within each module in isolation, so all dependencies were mocked.

Selected Technologies

• Database: PostgreSQL with SQLC
• Grpc: Protoc
• Configuration Management: Viper
• Logging: Zerolog

Run the Application in Docker Container

Option1: Using Docker Compose (recommended)

docker compose up

or

make up

use localhost:4445

Option2: Using Docker

Step 1.

docker build -t kazmerdome-muzz .

Step 2.

docker run --rm --network="host" -p 4445:4444 --env=POSTGRES_URI=postgresql://muzz:muzz@localhost:5432 --env=POSTGRES_DATABASE=muzz --env=POSTGRES_IS_SSL_DISABLED=true kazmerdome-muzz

use localhost:4445

Run the Application Locally

Step 1.

Run docker compose file for database and its migration

Option 1:

  `make up`

Option 2:

  `docker compose up`

Step 2.

  `cp .env.example .env`

Step 3.

Option 1 (Recommended):

  start applications using Visual Studio Code Run and Debug

Option 1:

  make run-gateway

Option 3:

  go run cmd/gateway/main.go

Step 4.

use localhost:4444