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Managing Environment-Specific Settings

To manage environment-specific settings in this project, you pass a configuration class to the create_app factory function. This allows you to toggle between development, testing, and production behaviors by changing which class from app/config.py is loaded.

Switch Environments via the Application Factory​

The create_app function in app/__init__.py defaults to DevelopmentConfig, but you can override it by passing any of the configuration classes.

from app import create_app
from app.config import ProductionConfig, TestingConfig, DevelopmentConfig

# For Production
app = create_app(config_class=ProductionConfig)

# For Testing
app = create_app(config_class=TestingConfig)

# For Development (Default)
app = create_app()

Development Configuration​

Use DevelopmentConfig for local work. It enables Flask's debug mode and uses a smaller page size to make manual testing of pagination easier.

  • File: app/config.py
  • Key Settings:
    • DEBUG = True
    • PAGE_SIZE = 10
    • Cache: Short-lived (30s TTL, 128 entries).
class DevelopmentConfig(BaseConfig):
    """Configuration for local development."""

    DEBUG: bool = True
    PAGE_SIZE: int = 10

    def get_cache_config(self) -> Dict[str, Any]:
        return _build_cache_config(ttl=30, max_size=128)

Production Configuration​

The ProductionConfig class enforces security by requiring environment variables and optimizes performance with larger cache limits.

  • File: app/config.py
  • Key Settings:
    • SECRET_KEY: Must be provided via the SECRET_KEY environment variable.
    • PAGE_SIZE: Uses the DEFAULT_PAGE_SIZE (25).
    • Cache: Long-lived (600s TTL, 4096 entries).

To run in production, ensure the environment variable is set:

export SECRET_KEY="your-secure-random-string"
python run.py

Testing Configuration​

The TestingConfig class is designed for automated test suites. It sets the TESTING flag and uses a very small page size (5) to ensure pagination logic is triggered even with small test datasets.

  • File: app/config.py
  • Key Settings:
    • TESTING = True
    • PAGE_SIZE = 5
class TestingConfig(BaseConfig):
    """Configuration for test runs."""

    TESTING: bool = True
    PAGE_SIZE: int = 5

Troubleshooting: Missing Secret Key​

If you attempt to initialize the application with ProductionConfig without setting the SECRET_KEY environment variable, the application will fail immediately with a KeyError.

Error: KeyError: 'SECRET_KEY'

Solution: Ensure the environment variable is exported before starting the server:

# Example for local production-like testing
export SECRET_KEY=$(python -c 'import os; print(os.urandom(24).hex())')

Note that BaseConfig and DevelopmentConfig provide a default value of "change-me", so they do not require this environment variable to be set.