cfgtree 0.1.0

Similar opensource projects

• Openstack’s Olso.config

Configuration Storage

The trivial storage is a simple json file. The complete settings are placed inside it, such as:

{
    'setting1': 'value1',
    'setting2': 'value2',
    'setting3': 'value3',
}

But developer may want to organize in a more hierarchical structure, splitting into different files, etc.

Another typical file format for configuration is YAML, which is more human readable and allow inserting comments and so.

But, ultimately, all file format actually stores a hierarchical configuration.

Current Support:

• single Json file

Future support:

• Yaml file (with inplace save keeping comments and overall organization)

• Set of Yaml files

• Configuration server

Configuration Tree Description

Configuration hierarchy is to be described in a cfgtree.EnvironmentConfig inherited instance, inside the member .cfgtree, using helper classes such as StringCfg, ‘IntCfg’, ‘UserCfg’ or ‘PasswordCfg’. Each setting can be set by environment variable, command line parameter or by the storage file(s) itself.

Let’s take an example of an item defined at the first level of the hierarchy. It is defined as a ‘IntCfg’ with name ‘count’. It can be set by the following:

• environment variable APPLICATIONNAME_COUNT (where APPLICATIONNAME is an optional developer-defined prefix added to every environment variable to avoid conflicts)

• command line argument --count

• item count at the first level of a json file

Hierarchical structure is reflected in these different ways, to avoid conflicts. Now, the ‘count’ setting is set in a settings section called ‘general’:

• environment variable: APPLICATIONNAME_GENERAL_COUNT

• command line argument: --general-count

• Json has a first level named general, and inside one of the items is called count.

XPath syntax

A xpath-like syntax allows to reach any item of the configuration: <key1>.<key2>.<key3>.<item>.