confypy
Python 2.6, 2.7, 3.2 and 3.3 compatible
Simple Configuration Loading and Management
Usage
Once a config is configured with locations, it's values are accessed through
the data
attribute. Key or Attribute access is valid:
from confypy import Config
from confypy import Location
config = Config()
config.locations = [Location.from_env_keys(['FOO', 'BAR', 'BAZ'])]
print(config.data.FOO)
print(config.data.BAR)
print(config.data.BAZ)
# OR
print(config.data['FOO'])
print(config.data['BAR'])
print(config.data['BAZ'])
Built-In Parsers
By built-in, we mean confypy will automatically check for common config parsers of the following types:
- json (falls back to simplejson)
- yaml (pyyaml required)
- configparser (Python's own ConfigParser)
- python (load a module's dict)
It determines the parser to use by checking the file extension of any file paths. However, you are also free to override this.
The parser can manually be set in the Location.* declaration.
For example, each of the following assumes JSON:
Location.from_path('/data/foo.json')
So does this:
Location.from_path('/data/foo', parser='json')
And so does this:
import json
Location.from_path('/data/foo', parser=json.loads)
And this too: Note that the imported 'json' here is just a reference to the json.loads callable
import json
from confypy import Location
from confypy.loaders import load_file
from confypy.parsers import json
location = Location('data/foo', loader=load_file, parser=json)
Yes, the parser argument to Location can be a string
OR a callable
.
In fact, the various Location.* factories just handle passing the parser
arg for you.
Parsers are chosen from strings and file extensions with the following rules: (see confypy.parsers.parser_for_ext)
def parser_for_ext(ext):
mapping = {
'yml': yaml,
'yaml': yaml,
'json': json,
'ini': configparser,
'configparser': configparser
}
result = mapping.get(ext.lower(), None)
if result:
return result
raise ParserNotFound(ext)
Defaults
Each config supports a set of defaults provided at creation time.
from confypy import Config
from confypy import Location
defaults = {'foo':1, 'bar':2, 'baz':3}
config = Config(defaults=defaults)
If no locations are present, or if none of the locations, when loaded, return any valid data, the defaults will be when looking up values.
When locations are chained, the defaults represent the last location for a lookup before an error is raised.
Examples
Stop loading after the 1st successful load.
In the example below, the TEST_SETTINGS
environment variable will be
checked first. It's assumed that it's value will be a file path:
from_env_path
. It's also possible to just load environment variables
as key/values which will follow in another example.
So TEST_SETTINGS
will be checked first, if the file exists, the drama
stops there. If it doesn't exist, it moves on to the next Location
provided in the locations list.
Assuming our file contains this JSON:
{
"name": "Lucy"
}
We can do this:
from confypy import Config
from confypy import Location
config = Config()
config.locations = [
Location.from_env_path('TEST_SETTINGS'),
Location.from_path('/data/foo.json')
]
print(config.data.name)
Try to load everything and chain the results together.
The resultant config can be chained. Values will be looked up starting from the last location provided in the locations list, falling up to the first location provided in the location list.
In other words the lookup order is like this in a chain:
from confypy import Config
from confypy import Location
config = Config(chain=True)
config.locations = [
Location.from_env_path('TEST_SETTINGS'), # 5
Location.from_path('/data/foo.json'), # 4 ^
Location.from_path('/data/foo.yaml'), # 3 ^
Location.from_env_keys(['FOO', 'BAR', 'BAZ']), # 2 ^
Location.from_python('path.to.my.module') # 1 ^
]
In order to get this chaining, the Config
must be initialized with the
argument chain=True