wr-profiles 1.0.1

Example

# warehouse.py

from wr_profiles import Profile, Property

class _WarehouseProfile(Profile):
    profile_root = 'warehouse'

    host = Property('host', default='localhost')
    user = Property('user')
    password = Property('password', default='')

    @property
    def url(self):
        return '{user}:{password}@{host}'.format(user=self.user, password=self.password, host=self.host)

warehouse_profile = _WarehouseProfile()

print(warehouse_profile.url)

> export WAREHOUSE_SANDBOX_USER="sandbox-user"
> export WAREHOUSE_SANDBOX_PASSWORD="sandbox-password"
> export WAREHOUSE_PROD_USER="root"
> export WAREHOUSE_PROD_PASSWORD="bigSecret"
> export WAREHOUSE_PROFILE="sandbox"

> python warehouse.py
sandbox-user:sandbox-password@localhost

> WAREHOUSE_PROFILE="prod" python warehouse.py
root:bigSecret@localhost

Profile

A Profile represents a set of configuration values backed by environment variables. The active profile can be switched by changing just one environment variable – the one identifying the name of the profile to be used. Your code may be using more than one independent profile at a time, or a combination of interrelated profiles when changing one enclosing profile changes selection of sub-profiles.

For example, your code may be connecting to a data warehouse. Most of the time you connect to one instance, but in certain scenarios, say, when doing integration testing, you may wish to connect to a different instance. The configuration for this connection consists of multiple environment variables. Changing them all just to connect to a different warehouse should be as easy as setting a single environment variable.

A profile can be either live or frozen. A live profile always checks the backing environment variables. A frozen profile instance uses the values that were loaded before freezing and does not consult the environment variables.

In a single codebase, one usually has a single object whose properties are consulted to get the prop values of the active profile. The variables being consulted depend on the currently selected profile of the particular type. Profiles of one type have a common profile root. Profile root is the name that all environment variables backing this profile start with.

For example, a warehouse connection could be governed by a WarehouseProfile. In your code you would then refer to warehouse_profile, a singleton of this class. Profile root for this profile could be warehouse. The active warehouse profile would be pointed to by environment variable WAREHOUSE_PROFILE which holds the name of the active profile. If this variable was set to "local_replica", then the properties of warehouse profile would be loaded from environment variables that start with WAREHOUSE_LOCAL_REPLICA_.