Environment Variables

Overview

CoroNet uses environment variables to manage sensitive configuration data and customize application behavior. All environment variables should be stored in a .env file in the project root directory.

Never commit your .env file to version control. It contains sensitive information like API keys. The .gitignore file is already configured to exclude .env files.

Required Environment Variables

OPENAI_API_KEY

The OpenAI API key is required for the primary OCR functionality using GPT-4o-mini vision model.

.env

OPENAI_API_KEY=sk-proj-...

The application will fail to start if this variable is not set. See the OpenAI Setup guide for instructions on obtaining an API key.

Used in: app.py:15

app.py

from dotenv import load_dotenv
import os
from openai import OpenAI

load_dotenv()
client = OpenAI(api_key=os.getenv("OPENAI_API_KEY"))

Optional Environment Variables

Flask Configuration

While not currently exposed as environment variables in the code, you can add these common Flask settings:

.env

# Flask application settings
FLASK_ENV=development
FLASK_DEBUG=True
FLASK_PORT=5000
FLASK_HOST=127.0.0.1

# Flask secret key (recommended for production)
SECRET_KEY=your-secure-random-secret-key-here

The current implementation uses a hardcoded secret key (app.py:12). For production deployments, change this to use an environment variable:

app.secret_key = os.getenv("SECRET_KEY", "superclave")

File Storage Paths

The application automatically creates these directories if they don’t exist:

DATA_PATH: data/registros.csv - CSV file storing license plate records
UPLOADS_DIR: uploads/ - Directory for uploaded vehicle images

Configuration in code: app.py:17-22

app.py

BASE_DIR = os.path.dirname(__file__)
DATA_PATH = os.path.join(BASE_DIR, "data", "registros.csv")
UPLOADS_DIR = os.path.join(BASE_DIR, "uploads")

os.makedirs(os.path.dirname(DATA_PATH), exist_ok=True)
os.makedirs(UPLOADS_DIR, exist_ok=True)

Creating the .env File

Create the file

In your project root directory (where app.py is located), create a new file named .env:

touch .env

Add your API key

Open the .env file in a text editor and add your OpenAI API key:

.env

OPENAI_API_KEY=sk-proj-your-actual-key-here

Verify .gitignore

Confirm that .env is listed in your .gitignore file to prevent accidental commits:

cat .gitignore | grep .env

You should see *.env in the output.

Load environment variables

The application automatically loads environment variables using python-dotenv:

from dotenv import load_dotenv
load_dotenv()  # Called at app.py:14

Environment Variable Loading

CoroNet uses the python-dotenv package to load environment variables from the .env file:

from dotenv import load_dotenv
import os

load_dotenv()  # Loads variables from .env file
api_key = os.getenv("OPENAI_API_KEY")  # Access the variable

The load_dotenv() function:

Searches for a .env file in the current directory and parent directories
Loads all variables into the environment
Does not override existing environment variables
Silently fails if no .env file is found

Example .env File

Here’s a complete example .env file for CoroNet:

.env

# OpenAI Configuration (Required)
OPENAI_API_KEY=sk-proj-AbCdEfGhIjKlMnOpQrStUvWxYz1234567890

# Flask Configuration (Optional)
FLASK_ENV=development
FLASK_DEBUG=True
FLASK_PORT=5000
SECRET_KEY=change-this-to-a-random-secure-key-in-production

# Application Settings (Optional)
MAX_UPLOAD_SIZE=16777216  # 16MB in bytes
ALLOWED_EXTENSIONS=jpg,jpeg,png,gif

Verifying Configuration

To verify your environment variables are loaded correctly:

import os
from dotenv import load_dotenv

load_dotenv()

if os.getenv("OPENAI_API_KEY"):
    print("✓ OPENAI_API_KEY is set")
    print(f"  Key starts with: {os.getenv('OPENAI_API_KEY')[:10]}...")
else:
    print("✗ OPENAI_API_KEY is not set")

Security Best Practices

Follow these security guidelines to protect your API keys and sensitive data:

Never commit .env files - Always keep them in .gitignore
Use strong secret keys - Generate random keys for SECRET_KEY
Rotate API keys regularly - Update your OpenAI API key periodically
Limit API key permissions - Use keys with minimal required permissions
Use different keys per environment - Separate keys for development, staging, and production
Monitor API usage - Check your OpenAI dashboard for unexpected usage

Troubleshooting

Application won’t start

If you see an error related to the OpenAI client, ensure your .env file:

Exists in the project root directory (same location as app.py)
Contains a valid OPENAI_API_KEY variable
Has no extra spaces around the = sign
Has no quotes around the API key value