Class-based settings

An interesting way of laying out configurations for different deployment modes, such as production, testing, staging, and so on, can be cleanly done using the inheritance pattern of classes. As the project gets bigger, you can have different deployment modes such as development, staging, production, and so on, where each mode can have several different configuration settings, and some settings will remain the same.

How to do it…

We can have a default setting base class, and other classes can inherit this base class and override or add deployment-specific configuration variables.

The following is an example of our default setting base class:

class BaseConfig(object):
    'Base config class'
    SECRET_KEY = 'A random secret key'
    DEBUG = True
    TESTING = False
    NEW_CONFIG_VARIABLE = 'my value'

class ProductionConfig(BaseConfig):
    'Production specific config'
    DEBUG = False
    SECRET_KEY = open('/path/to/secret/file').read()

class StagingConfig(BaseConfig):
    'Staging specific config'
    DEBUG = True

class DevelopmentConfig(BaseConfig):
    'Development environment specific config'
    DEBUG = True
    TESTING = True
    SECRET_KEY = 'Another random secret key'

Tip

The secret key is stored in a separate file because, for security concerns, it should not be a part of your version-control system. This should be kept in the local filesystem on the machine itself, whether it is your personal machine or a server.

How it works…

Now, we can use any of the preceding classes while loading the application's configuration via from_object(). Let's say that we save the preceding class-based configuration in a file named configuration.py:

app.config.from_object('configuration.DevelopmentConfig')

So, overall, this makes the management of configurations for different deployment environments flexible and easier.

Tip

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