Skip to content

Latest commit

 

History

History
70 lines (47 loc) · 2.88 KB

README.md

File metadata and controls

70 lines (47 loc) · 2.88 KB
Raw

Centroid - Python

This document includes information specific to Python in Centroid. Refer to the Centroid document for general information, including information the JSON configuration file.

Installation

The Centroid Python package is hosted at PyPi.

Install Centroid using pip with pip install centroid or by downloading Centroid, unpacking it, and using python setup.py install.

Config Class with Python

In Python, the centroid.Config class exposes the following:

  • Static from_file method
  • Constructor
  • for_environment instance method
  • __contains__ instance method

Note: The examples given in the following sections are based on the JSON configuration file examples in the Centroid doucment.

from_file Method

Using the static Config.from_file(filename) method, you can create an instance of Config from a JSON file, as in the example below.

# from_file.py
config = Config.from_file("config.json")
server = config.database.server_address # => "my-server.local"

Config Constructor

To load a string instead of a file, create an instance of Config by passing a JSON string to the Config constructor, as in the following example.

# from_string.py
json = '{ "database": { "serverAddress": "my-server.local" } }'
config = Config(json)
server = config.database.server_address # => "my-server.local"

for_environment Instance Method

In the Config instance, you can use the for_environment instance method to retrieve the configuration values for an environment.

If you specify an environment in for_environment, Centroid will merge the requested environment's configuration values with the values in all. Refer to Examples in the Centroid document for information on creating an environment-based JSON configuration file.

To maintain environment awareness, this call adds an environment configuration value, unless your JSON contains an environment (case-insensitive) property already.

With the following example, Centroid will merge the configuration for prod with the configuration for all; the result is then available from a new instance of Config.

# for_enviroment.py
config = Config.from_file("config.json").for_environment("prod")
environment = config.environment # => "prod"
server = config.some_resource.server # => "resource-prod.local"
solution_path = config.keys.ssh # => "path/to/id_rsa.pub"

__contains__ Instance Method

In a Config instance, the __contains__ method allows for determining if a key exists, by using the in and not in operators. This method uses the same case and underscore rules as is used for value lookups.

json = '{ "database": { "serverAddress": "my-server.local" } }'
config = Config(json)
"Database" in config # => True
"does_not_exist" in config # => False