bank_ops

API Service to perform the basic operations of a Bank

Technology Stack

• Golang
• Postgres

Setup Instructions

Clone App from Git

Open terminal and execute below commands:

# Clone the repository on desired path.
$ git clone git@github.com:jass-walia/bank_ops.git

# Move to cloned directory.
$ cd bank_ops

Run via Docker

Note: You may want to look into .env file to review the environment setting.

# Run via docker-compose.
$ docker-compose up -d

Logging

To view app logs:

# Optional use of flag `--follow` to tail the logs.
$ docker logs bank --follow

Run Manually

Install the Pre-requisites on your machine

• Golang v1.14 or higher
• PostgreSQL

Setup database

Note: You need to edit the value of DB_HOST to localhost and DB_PORT to the local postgres instance port, in .env file.

# This will create the required database and user for the app.
#
# Give executable permission to the bash script and run.
$ chmod +x setup-db.sh
$ ./setup-db.sh

Build, Test and Run

# Run all tests.
$ go test ./... -v

# Build the binary.
$ go build -o main .

# Finally, run the binary with the flag to record logs to standard error.
$ ./main -logtostderr

API Documentation

Note: Params with asterisk sign (*) are mandatory.

Create Account

[POST] /api/v1/accounts

Body Params:

• *account_holder_name string
• *account_type string: Allowed values: saving or current

Request:

{
    "account_holder_name": "David",
    "account_type": "saving"
}

Success Response:

{
    "created_at": "2022-02-15T14:03:42.7151735+05:30",
    "uid": "a6d08354-d327-4266-9e94-8f32d69719ab",
    "account_holder_name": "David",
    "account_number": 1,
    "account_type": "saving"
}

Error Response:

{"errors": []}

Status Codes:

• 201: Account Created
• 400: Bad Request
• 422: Client Validation Error
• 500: Internal Server Error

Make Transaction

[POST] /api/v1/accounts/:uid/transaction

Path Params:

*uid string: Account UID returned on creating an account.

Body Params:

• *amount float: Upto 2 decimal places.
• *type string: Type of transaction, allowed values: credit or debit
• narration string: Optional comment about transaction.

Request:

{
    "amount": 100,
    "type": "credit",
    "narration": "My first saving"
}

Success Response:

{
    "created_at": "2022-02-15T14:08:19.8218828+05:30",
    "uid": "a08efdc4-c304-4706-bb2b-d243c8c61dd7",
    "narration": "My first saving",
    "credit": 100,
    "debit": 0,
    "account": {
        "created_at": "2022-02-15T14:03:42.715173+05:30",
        "uid": "a6d08354-d327-4266-9e94-8f32d69719ab",
        "account_holder_name": "David",
        "account_number": 1,
        "account_type": "saving"
    }
}

Error Response:

{"errors": []}

Status Codes:

• 201: Transaction Completed
• 400: Bad Request
• 404: Account Not Found
• 422: Client Validation Error
• 500: Internal Server Error

Get Balance

[GET] /api/v1/accounts/:uid/balance

Params:

*uid string: Account UID returned on creating an account.

Success Response:

{
    "balance": 100
}

Error Response:

{"errors": []}

Status Codes:

• 200: Success
• 404: Account Not Found
• 500: Internal Server Error

Trade-offs

Unit Testing

Problem: Unit tests are using test database requires database setup

I'm using some test database to execute the unit tests, which violates the unit test definition and gives it a flavour of integration test.

Solution

One should think of mocking database to eliminate the need of database setup for running tests.

Integration Testing

I believe integrations tests should be performed in a clean way without leaving any test data behind after tests are finished. I personally like dockertest, a golang package which spins up the database container on-the-fly for testing and removes it after completion. And, I think it is even a good alternative of mocking database.

Improvements

• Provide http handlers for liveness and readiness signals, will be useful for distributed systems like kubernetes who generally demands these endpoints to understand the pods' health more efficiently.

• Automate test encouraging Continous Integration using GitHib Actions feature or even Jenkins.

Who do I talk to?

• jaspreet.surmount@gmail.com