FACEIT Challenge

Task

Write a small microservice to manage access to Users, the service should be implemented in Go

Requirements

A user must be stored using the following schema:

{
    "id": "<id>",
    "first_name": "Alice",
    "last_name": "Bob",
    "nickname": "ab234",
    "password": "secretpwd",
    "email": "alice@bob.com",
    "country": "UK",
    "created_at": "2019-10-12T07:20:50.52Z",
    "updated_at": "2020-10-12T07:20:50.52Z"
}

Provide an HTTP/gRPC API
Use a sensible storage for the Users
Have the ability to notify other interested services of changes to User entities
Have meaninful logs
Be well documented
Have an health check

Functionalities

Add a new User
Modify an existing user
Remove a user
Return a paginated list of Users, allowing for filtering by certain criteria (All users with the country UK)

Considerations

Most of these considerations/choices have been taken due to the lack of time and the nature of this exercise. Focusing on make things right and writing tests requires in general more time but it gives more confidence and helps writing more robust softwares, I hope it is going to take into consideration during the final evaluation.

ID Format: The schema specifies UUIDs, but MongoDB's hex format for ObjectIDs is used instead. This choice improves insert performance and simplifies update/delete operations.
Password Security: Passwords are hashed with bcrypt. Future improvements could include salting with an internal constant and extracting hashing into a separate module for enhanced security.
Pagination and Streaming: The current implementation uses pagination. Streaming might be considered for handling larger datasets or higher limits in the future.
Testing: I tried to test the most critical part of the application. The gRPC implementation lacks comprehensive testing due to time constraints. More extensive testing should be added on that part but considering the scope of this exercise I guessed that could be omitted.
Project Structure: Domain-Driven Design (DDD) principles were applied for better separation of concerns. Additional field validations could be beneficial.
Have in place more field validations.
Port Configuration: The HTTP server runs on port 80, while the gRPC server is on port 8080. Only the HTTP server is public exposed. Typically, gRPC servers are used for internal communication and require different security considerations.
Missing Endpoints: The "getUser" endpoint is omitted as it was not specified in the requirements, allowing focus on other critical functionalities.
Configuration and Logging: The application uses default configuration and logging mechanisms. Future work could improve configuration management and use advanced logging libraries like zap.
Web Server Gorilla/Mux has been used for the web server, it is simple to use and effective for what needed.

Testing Strategy

Testing is one of the most important part when writing software.
Personally I like the Test Driven Development approach following the Boston approach (inside-out).

In the data layer I wrote integration tests, using Testcontainers, specifically the MongoDB module. It helps to stay as close as possible to real scenarios.
In the business level I wrote unit tests, mocking the dependencies with testify.

How to run all tests

Having docker up and running
go test ./...

How to run the project

Have docker up and running
docker-compose up --build

HTTP Create user

Through the endpoint: /api/user using the POST method.

Request:

dlion@darkness ~ % curl -X POST http://localhost:80/api/user \
     -H "Content-Type: application/json" \
     -d '{
           "first_name": "John",
           "last_name": "Doe",
           "nickname": "john.doe",
           "email": "john.doe@future.com",
           "password": "supersecurepassword",
           "country": "UK"
         }'

Response:

{
  "id": "669a5b3525ff5682bea961ba",
  "first_name": "John",
  "last_name": "Doe",
  "nickname": "john.doe",
  "email": "john.doe@future.com",
  "country": "UK",
  "created_at": "2024-07-19T12:25:25Z",
  "updated_at": "2024-07-19T12:25:25Z"
}

The password is not returned for security reason.

HTTP Modify user

Through the endpoint: /api/user/{id} using the PUT method.

Request:

curl -X PUT http://localhost:80/api/user/669a5b3525ff5682bea961ba \
 -H "Content-Type: application/json" \
 -d '{ "first_name": "Paco" }'

Response:

{
 "id": "669a5b3525ff5682bea961ba",
 "first_name": "Paco",
 "last_name": "Doe",
 "nickname": "john.doe",
 "email": "john.doe@future.com",
 "country": "UK",
 "created_at": "2024-07-19T12:25:25Z",
 "updated_at": "2024-07-19T12:28:52Z"
}

HTTP Delete User

Through the endpoint: /api/user/{id} using the DELETE method.

curl -X DELETE http://localhost:80/api/user/669a5b3525ff5682bea961ba

Response: HTTP Status 200

* Host localhost:80 was resolved.
* IPv6: ::1
* IPv4: 127.0.0.1
*   Trying [::1]:80...
* Connected to localhost (::1) port 80
> DELETE /api/user/669a5dd6ed1bb58da5fe8ba7 HTTP/1.1
> Host: localhost
> User-Agent: curl/8.6.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Fri, 19 Jul 2024 12:36:47 GMT
< Content-Length: 0
<
* Connection #0 to host localhost left intact

HTTP List Users

Through the endpoint: /api/users using the GET method.

Filters available:

first_name
last_name
nickname
email
country
limit
offset

Request Examples

Simple request: curl http://localhost:80/api/users

Response:

[
  {
    "id": "669a49151d6327b831fb4797",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssdaohqqndoe",
    "email": "121232q222dsds3222john.a@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:08:05Z",
    "updated_at": "2024-07-19T11:08:05Z"
  },
  {
    "id": "669a4800ccfd366bb0843dfd",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssd25jaohqqndoe",
    "email": "121232q222dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:03:28Z",
    "updated_at": "2024-07-19T11:03:28Z"
  },
  {
    "id": "669a47b7e383b231d3f1af2c",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohqqndoe",
    "email": "121232q2dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:02:15Z",
    "updated_at": "2024-07-19T11:02:15Z"
  },
  {
    "id": "669a46da7ce4c0c9585ed7ee",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohndoe",
    "email": "121232q2dsds3222john.adoe@example.com",
    "country": "UK",
    "created_at": "2024-07-19T10:58:34Z",
    "updated_at": "2024-07-19T10:58:34Z"
  },
  ...
]

Request with a limit: curl "http://localhost:80/api/users?limit=2"

Response:

[
  {
    "id": "669a49151d6327b831fb4797",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssdaohqqndoe",
    "email": "121232q222dsds3222john.a@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:08:05Z",
    "updated_at": "2024-07-19T11:08:05Z"
  },
  {
    "id": "669a4800ccfd366bb0843dfd",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssd25jaohqqndoe",
    "email": "121232q222dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:03:28Z",
    "updated_at": "2024-07-19T11:03:28Z"
  }
]

Request with offset: curl "http://localhost:80/api/users?offset=2"

Response:

[
  {
    "id": "669a47b7e383b231d3f1af2c",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohqqndoe",
    "email": "121232q2dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:02:15Z",
    "updated_at": "2024-07-19T11:02:15Z"
  },
  {
    "id": "669a46da7ce4c0c9585ed7ee",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohndoe",
    "email": "121232q2dsds3222john.adoe@example.com",
    "country": "UK",
    "created_at": "2024-07-19T10:58:34Z",
    "updated_at": "2024-07-19T10:58:34Z"
  },
  {
    "id": "669a46b47ce4c0c9585ed7ed",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "112q1122122dssd25jaohndoe",
    "email": "121121232q2dsds3222john.adoe@example.com",
    "country": "USA",
    "created_at": "2024-07-19T10:57:56Z",
    "updated_at": "2024-07-19T10:57:56Z"
  },
  ...
]

Request with country filter: curl "http://localhost:80/api/users?country=UK"

Response:

[
  {
    "id": "669a49151d6327b831fb4797",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssdaohqqndoe",
    "email": "121232q222dsds3222john.a@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:08:05Z",
    "updated_at": "2024-07-19T11:08:05Z"
  },
  {
    "id": "669a4800ccfd366bb0843dfd",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssd25jaohqqndoe",
    "email": "121232q222dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:03:28Z",
    "updated_at": "2024-07-19T11:03:28Z"
  },
  {
    "id": "669a47b7e383b231d3f1af2c",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohqqndoe",
    "email": "121232q2dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:02:15Z",
    "updated_at": "2024-07-19T11:02:15Z"
  },
  {
    "id": "669a46da7ce4c0c9585ed7ee",
    "first_name": "John",
    "last_name": "Doe",
    "nickname": "11212q1122122dssd25jaohndoe",
    "email": "121232q2dsds3222john.adoe@example.com",
    "country": "UK",
    "created_at": "2024-07-19T10:58:34Z",
    "updated_at": "2024-07-19T10:58:34Z"
  }
]

Request with country filter and limit: curl "http://localhost:80/api/users?country=UK&limit=2"

Response:

[
  {
    "id": "669a49151d6327b831fb4797",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssdaohqqndoe",
    "email": "121232q222dsds3222john.a@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:08:05Z",
    "updated_at": "2024-07-19T11:08:05Z"
  },
  {
    "id": "669a4800ccfd366bb0843dfd",
    "first_name": "John",
    "last_name": "D11oe",
    "nickname": "11q212q1122122dssd25jaohqqndoe",
    "email": "121232q222dsds3222john.adoe@qqexample.com",
    "country": "UK",
    "created_at": "2024-07-19T11:03:28Z",
    "updated_at": "2024-07-19T11:03:28Z"
  }
]

gRPC Functions

GetUsers(GetUsersRequest) returns (GetUsersResponse);
CreateUser(CreateUserRequest) returns (User);
UpdateUser(UpdateUserRequest) returns (User);
DeleteUser (DeleteUserRequest) returns (Empty);
Watch(google.protobuf.Empty) returns (stream WatchResponse);

dlion/faceit_challenge

FACEIT Challenge

Task

Requirements

Functionalities

Considerations

Testing Strategy

How to run all tests

How to run the project

HTTP Create user

HTTP Modify user

HTTP Delete User

HTTP List Users

Request Examples

gRPC Functions