Stori Transactions Email Generator

Overview

This application offers a solution for managing and reporting on account balances.

Key Features

Email Notifications

Users can send comprehensive account balance emails, including:

• Total Account Balance: The overall balance of the account.
• Average Debit Amount: The average amount of all debit transactions.
• Average Credit Amount: The average amount of all credit transactions.
• Transactions History: The number of transactions processed each month (and year).

CSV Input File

The application requires detailed CSV files containing the following columns:

• Id: A unique identifier for each transaction.
• Date: The transaction date in MM/DD/YYYY format.
• Transaction: The amount of the transaction, marked with + for credits and - for debits.

Command Line Interface (CLI)

A simple CLI is available, offering:

• Account managment: Create accounts.
• Load account transactions: Load transactions to database through CSV provided files.
• Send balance: nNotify users by sending custom emails with detailed data.

API Deployment

The API is deployed on AWS, providing:

• Basic endpoints to manage accounts and transactions.
• Endpoints to create presigned urls to upload files to S3.
• Endpoints to process transactions files.
• Endpoint to send account balances by email.

AWS Integration:

• AWS S3: For storing and retrieving CSV files.
• AWS SecretsManager: For secure credentials storage.
• AWS RDS (PostgreSQL): For database management.

Local Environment Setup

Requirements

• Python 3.12
• Docker Desktop
• Docker Compose

Setup

Create a virtual environment:

python3.12 -m venv venv

Activate the environemnt:

source venv/bin/activate

Install dependencies:

pip install -r requirements.txt

Configure the email sender service credentials:

cp .env.example .env

Set SENDGRID_SENDER_EMAIL and SENDGRID_API_KEY in .env file to enable sending emails trough SendGrid service.

Once all dependencies are installed there are two options to run the server, could be executed locally or in a docker container.

Build images with docker compose:

 docker compose up --build --force-recreate --detach

Be sure the docker daemon is running.

Command Line Interface

The CLI allows three diffent flows:

• create_account: register a new account to the database.
• load_transactions: register account related transactions.
• send_balance: send a balance summary to account's registered email.

CLI Help:

$ docker run -v transactions-email-generator-app:latest -h
usage: cli.py [-h] {create_account,load_transactions,send_balance} ...

A command line tool with multiple flows.

positional arguments:
  {create_account,load_transactions,send_balance}
                        Choose the flow to execute
    create_account      Execute create_account flow. Requires parameters
                        --name (str) and --email (str)
    load_transactions   Execute load_transactions flow. Requires parameters
                        --account-id and --path-to_file
    send_balance        Execute send_email flow. Requires parameters
                        --account-id, --from_date and --to_date

optional arguments:
  -h, --help            show this help message and exit

API Description

With the image transactions-email-generator-app built and running the following flows can be executed:

Create Account

docker run transactions-email-generator-app:latest create_account --name "Stori Card" --email storinoreply@gmail.com

Load Transactions

docker run -v ./csv:/csv transactions-email-generator-app:latest load_transactions --account-id 1 --path-to-file /csv/transactions_10k.csv

Note that for this command a virtual volume mapping is provided to mount csv local directory into /csv directory in the container.

Send Balance

docker run transactions-email-generator-app:latest send_balance --account-id 1

Endpoints

API Description

Endpoints

The available endpoints are as follows:

Endpoint	Method	Description	Parameters	Output
/	GET	Root endpoint.	NA	A welcome message, the API is running and accepting requests.
/presigned_url	GET	Get an URL to post a file bigger than 10Mb. Note: it is required to use an external tool to post the file to s3 (i.e. Postman, or the requests module).	NA	A dict with url and fields to upload a file to s3.
/load_transactions_s3	POST	Post a request to save transactions from a previously uploaded file using the presigned URL obtained through /presigned_url.	account_id and file_id	A message informing the file was successfully processed or an error message instead.
/load_transactions	POST	Post a file processing request by providing the file (size limit is <10Mb)	account_id and file	A message informing the file was successfully processed or an error message instead.
/send_balance	POST	Post a request to gather account transactions and send a balance summary to account's email.	account_id	A message informing the email was send sucessfully, or an error message instead.

Post a file to presigned url:

Install dependency:

python -m pip install requests

Reference script:

import requests

"""
Script to get a presigned URL and upload a file to s3.
"""

HOST = "https://rkes7qxbb0.execute-api.us-west-2.amazonaws.com"  # Dev environment
# HOST = "http://127.0.0.1/"  # Local environment
PATH_TO_FILE = "csv/transactions_1.csv"

# Get presigned URL
presigned_url_info = requests.get(f"{HOST}/presigned_url").json()

# Upload the file to the presigned URL
with open(PATH_TO_FILE, "rb") as f:
    filebody = f.read()

print("Uploading file to s3...")
upload_response = requests.post(
    presigned_url_info["url"],
    data=presigned_url_info["fields"],
    files={
        "file": (
            presigned_url_info["fields"]["key"],
            filebody,
            "text/csv",
        )
    },
)
print("File uploaded with file_id: ", presigned_url_info["fields"]["key"])