Metadata-Version: 1.2
Name: wr-profiles
Version: 2.1.0
Summary: Switch environment variable based profiles in Python with ease
Home-page: https://github.com/jbasko/wr-profiles
Author: Jazeps Basko
Author-email: jazeps.basko@gmail.com
Maintainer: Jazeps Basko
Maintainer-email: jazeps.basko@gmail.com
License: MIT
Description: ## Disclaimer
        
        *wr-* in the package name stands for *Wheel Reinvented*. Just like all other packages whose name starts with
        *wr-*, the meaning of this library (as in *meaning of life*) lies in its existence and evolution 
        and not in any external application of it.
        
        ## Why Do I Need This?
        
        You don't.
        
        But you could find it useful if you use environment variables as primary means of passing 
        configuration to your program, and you have scenarios when your program has to switch between sets of 
        environment variables.
        
        ## Example
        
        Here's an example of declaring a profile with three properties and using it to consult the values
        of these properties. More advanced examples are available in the user guide below.
        
        This example works in Python 3.6+. In Python 3.5 you need to pass the name of the property 
        to the `Property` initialiser: `password = Password('password')`.
        
        
            import os
            from wr_profiles import Profile, Property
            
            class WarehouseProfile(Profile):
                profile_root = 'warehouse'
                username = Property(default='default-username')
                password = Property()
            
            # export WAREHOUSE_PROFILE=staging
            # export WAREHOUSE_STAGING_PARENT_PROFILE="production"
            # export WAREHOUSE_STAGING_PASSWORD="staging-password"
            # export WAREHOUSE_PRODUCTION_USERNAME="production-username"
            # export WAREHOUSE_PRODUCTION_PASSWORD="production-password"
            
            warehouse_profile = WarehouseProfile()
            assert warehouse_profile.username == 'production-username'
            assert warehouse_profile.password == 'staging-password'
        
        ## Installation
        
            pip install wr-profiles
            
        If you decide to use this library, make sure you pin the version number in your requirements file.
        
        ## User Guide
        
        ### Concepts
        
        ##### Profile
        
        A **profile** represents a set of configurable **properties** of a single service
        backed by environment variables.
        
        There can be multiple unrelated profiles (multiple classes extending `Profile` class),
        each providing interface to properties of a different service.
        
        Instances of profiles associated with the same service share the same base class and are identified by
        `profile_root` specified in that base class. Is is the root from which all relevant 
        environment variable names are formed.
        
        Profiles of unrelated services do not share any information.
        In the discussion below, different instances or kinds of profiles all relate to the same service,
        e.g. same `profile_root`.
        
        ##### Warehouse Profile (Example)
        
        In the discussion below, we will use a profile for a data warehouse access as an example.
        Class `WarehouseProfile` declares the profile and the properties it provides.
        Object `warehouse_profile` is the single instance through which user must look up service's
        active configuration.
        
            class WarehouseProfile(Profile):
                profile_root = 'warehouse'
                
                host = Property(default='localhost')
                username = Property()
                password = Property(default='')
            
            warehouse_profile = WarehouseProfile()
        
        ##### Profile Name
        
        Individual instances of profiles are identified by their name (`profile_name` property).
        
        ##### Active Profile
        
        The **active profile** is the profile of a service that should be used 
        according to the environment variables.
        
        The active profile can be switched by setting a special environment variable
        `<PROFILE_ROOT>_PROFILE`. For `WarehouseProfile` that would be `WAREHOUSE_PROFILE`.
        
        If this variable is not set, the active profile consults environment variables in the
        form:
        
            <PROFILE_ROOT>_<PROPERTY_NAME>
        
        For example, `WAREHOUSE_HOST`.
        
        If `<PROFILE_ROOT>_PROFILE` is set then the active profile consults environment variables in the form:
        
            <PROFILE_ROOT>_<PROFILE_NAME>_<PROPERTY_NAME>
        
        For example, if `WAREHOUSE_PROFILE` is set to `staging` then `host` property will be looked up
        under `WAREHOUSE_STAGING_HOST`.
        
        ##### Parent Profile
        
        Any particular profile (for example, `staging` profile of `WarehouseProfile`) can be instructed
        to inherit its property values from a **parent profile** by setting:
        
            <PROFILE_ROOT>_<PROFILE_NAME>_PARENT_PROFILE
        
        For example, `WAREHOUSE_STAGING_PARENT_PROFILE`, if set to `production`, would mean that
        if environment variable `WAREHOUSE_STAGING_HOST` was not set, property value loader would
        consult `WAREHOUSE_PRODUCTION_HOST` instead. And only if that variable was not present,
        the default value of the property (if available) would be used.
        
        *Limitation*: The default profile (`profile_name=""`) cannot be used as a parent profile.
        If you specify empty string as `<PROFILE_ROOT>_<PROFILE_NAME>_PARENT_PROFILE` then this
        profile won't have any parent profile. It is the same as having no value set. 
        
        ##### Live Profile vs Frozen Profile
        
        A **live** profile always consults environment variables (`os.environ`) whereas
        a **frozen** profile does so only during instantiation and when explicitly loaded
        with `load()` method.
        
        ### Scenarios
        
        ##### Current Active Profile
        
        Current active profile is always available through the instance of your profile class which is
        instantiated with no arguments:
        
            warehouse_profile = WarehouseProfile()
        
        Normally you'd only need a single instance of your profile class.
        
        ##### Concrete Profile
        
        To work with a concrete profile which may not necessarily be activated, use `get_instance`
        factory method:
        
            staging = WarehouseProfile.get_instance('staging')
        
        By default, this profile will be frozen which means it will be loaded only once during instantiation.
        If you want it to always consult environment variables, pass `is_live=True`:
        
            staging = WarehouseProfile.get_instance('staging', is_live=True)
        
        ##### Activate Profile
        
        To activate a profile, call `activate` method on a frozen instance of the profile without any arguments,
        or, `activate(profile_name)` on the live current profile instance:
        
            staging.activate()
            
            # or:
            
            warehouse_profile.activate('staging')
        
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: License :: OSI Approved :: MIT License
