Trafaret Config

Status:

Stable

Documentation:

http://trafaret-config.readthedocs.io/

This is a wrapper that loads yaml and checks config using trafaret while keeping track of actual lines of file where error has happened. Additionally, it can pretty print the error.

Basic Usage:

import argparse
import trafaret
from trafaret_config import commandline

TRAFARET = trafaret.Dict({'x': trafaret.String()})

def main():
    ap = argparse.ArgumentParser()
    commandline.standard_argparse_options(ap, default_config='config.yaml')
    #
    # define your command-line arguments here
    #
    options = ap.parse_args()
    config = commandline.config_from_options(options, TRAFARET)
    pprint.pprint(config)

Example output when there is an error in config (from a example.py which has better trafaret than example above):

bad.yaml:3: smtp.port: value can't be converted to int
  -> 'unknown'
bad.yaml:4: smtp.ssl_port: value can't be converted to int
  -> 'NaN'
bad.yaml:5: port: value can't be converted to int
  -> '???'

Help looks like this:

usage: example.py [-h] [-c CONFIG] [--print-config] [--print-config-vars] [-C]

optional arguments:
  -h, --help            show this help message and exit
  -c CONFIG, --config CONFIG
                        Configuration file (default: 'config.yaml')
  --print-config        Print config as it is read after parsing and exit
  --print-config-vars   Print variables used in configuration file
  -C, --check-config    Check configuration and exit

Since trafaret-config 2.0 environment variables in the config are replaced by default, this means that config like this:

url: http://${HOST}:$PORT/

Will get HOST and PORT variables insert from the environment, and if variable does not exist, you will get the following error:

config.yaml:2: variable 'PORT' not found
  -> 'http://${HOST}:$PORT/'

Low-level interface, without relying on argparse:

import sys
import trafaret
from trafaret_config import ConfigError, read_and_validate

TRAFARET = trafaret.Dict({'x': trafaret.String()})

try:
    config = read_and_validate('config.yaml', TRAFARET)
except ConfigError as e:
    e.output()
    sys.exit(1)

pip install trafaret-config==2.0.2