I need to read follow yaml-formatted configuration file:
version: 1
disable_existing_loggers: False
formatters:
precise:
format: "%(name)-15s # %(levelname)-8s # %(asctime)s # [Line: %(lineno)-3d]: %(message)s"
datefmt: "%Y-%m-%d %H:%M:%S"
handlers:
file:
class: logging.handlers.RotatingFileHandler
filename: <%= ENV['ENV_PROJECT'] %>/target/tracing.log
encoding: utf-8
maxBytes : 10737418244
backupCount: 7
formatter: precise
loggers:
utility:
handlers: [file]
level: INFO
propagate: True
root:
handlers: [file]
level: INFO
But, instead off <%= ENV['ENV_PROJECT'] %> in the result string I need to get the relevant path, for example. For the loading this file I use follow code:
from yaml import load
with open('test.yml', 'rt') as stream:
configuration = load(stream)
How can I get the required result? Tnx.
You need to use 'resolver' and 'constructor' to achieve this. Here is one way to achieve this.
import yaml, os, re
#define the regex pattern that the parser will use to 'implicitely' tag your node
pattern = re.compile( r'^\<%= ENV\[\'(.*)\'\] %\>(.*)$' )
#now define a custom tag ( say pathex ) and associate the regex pattern we defined
yaml.add_implicit_resolver ( "!pathex", pattern )
#at this point the parser will associate '!pathex' tag whenever the node matches the pattern
#you need to now define a constructor that the parser will invoke
#you can do whatever you want with the node value
def pathex_constructor(loader,node):
value = loader.construct_scalar(node)
envVar, remainingPath = pattern.match(value).groups()
return os.environ[envVar] + remainingPath
#'register' the constructor so that the parser will invoke 'pathex_constructor' for each node '!pathex'
yaml.add_constructor('!pathex', pathex_constructor)
#that is it
data = """
version: 1
disable_existing_loggers: False
formatters:
precise:
format: "%(name)-15s # %(levelname)-8s # %(asctime)s # [Line: %(lineno)-3d]: %(message)s"
datefmt: "%Y-%m-%d %H:%M:%S"
handlers:
file:
class: logging.handlers.RotatingFileHandler
filename: <%= ENV['ENV_PROJECT'] %>/target/tracing.log
encoding: utf-8
maxBytes : 10737418244
backupCount: 7
formatter: precise
loggers:
utility:
handlers: [file]
level: INFO
propagate: True
root:
handlers: [file]
level: INFO
"""
deSerializedData = yaml.load(data)
print(deSerializedData [ 'handlers'] [ 'file' ] ['filename'] )