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Hierarchical Yaml Python Config

Project description


HiYaPyCo - A Hierarchical Yaml Python Config


A simple python lib allowing hierarchical overlay of config files in
YAML syntax, offering different merge methods and variable interpolation
based on jinja2.

The goal was to have something similar to puppets hiera
``merge_behavior: deeper`` for python.

Key Features

- hierarchical overlay of multiple YAML files
- multiple merge methods for hierarchical YAML files
- variable interpolation using jinja2


- PyYAML aka. python-yaml
- Jinja2 aka. python-jinja2
- ordereddict for python2.6 (if you like to use the Ordered Dict Yaml
Loader / Dumper aka. ODYLDo)

Python Version

HiYaPyCo was designed to run on both current major python versions
without changes. Tested versions:

- 2.6
- 2.7
- 3.2
- 3.4


A simple example:


import hiyapyco
conf = hiyapyco.load('yamlfile1' [,'yamlfile2' [,'yamlfile3' [...]]] [,kwargs])

real life example:



first: first element
second: xxx
- 1
- 2



second: again {{ first }}
- 4
- 6
- 3
- 6

load ...


>>> import pprint
>>> import hiyapyco
>>> conf = hiyapyco.load('yaml1.yaml', 'yaml2.yaml', method=hiyapyco.METHOD_MERGE, interpolate=True, failonmissingfiles=True)
>>> pprint.PrettyPrinter(indent=4).pprint(conf)
{ 'deep': { 'k1': [1, 2, 4, 6], 'k2': [3, 6]},
'first': u'first element',
'ma': { 'ones': u'12', 'sum': u'22'},
'second': u'again first element'}

real life example using yaml documents as strings


>>> import hiyapyco
>>> y1="""
... yaml: 1
... y:
... y1: abc
... y2: xyz
... """
>>> y2="""
... yaml: 2
... y:
... y2: def
... y3: XYZ
... """
>>> conf = hiyapyco.load([y1, y2], method=hiyapyco.METHOD_MERGE)
>>> print (conf)
OrderedDict([('yaml', 2), ('y', OrderedDict([('y1', 'abc'), ('y2', 'def'), ('y3', 'XYZ')]))])
>>> hiyapyco.dump(conf, default_flow_style=True)
'{yaml: 2, y: {y1: abc, y2: def, y3: XYZ}}\n'


All ``args`` are handled as *file names* or *yaml documents*. They may
be strings or list of strings.


- ``method``: bit (one of the listed below):

- ``hiyapyco.METHOD_SIMPLE``: replace values (except for lists a
simple merge is performed) (default method)
- ``hiyapyco.METHOD_MERGE``: perform a deep merge

- ``interpolate``: boolean : perform interpolation after the merge
(default: False)

- ``castinterpolated``: boolean : try to perform a *best possible
match* cast for interpolated strings

- ``usedefaultyamlloader``: boolean : force the usage of the default
*PyYAML* loader/dumper instead of *HiYaPyCo*\ s implementation of a
OrderedDict loader/dumper (see: Ordered Dict Yaml Loader / Dumper
aka. ODYLDo) (default: False)

- ``failonmissingfiles``: boolean : fail if a supplied YAML file can
not be found (default: True)

- ``loglevel``: int : loglevel for the hiyapyco logger; should be one
of the valid levels from ``logging``: 'WARN', 'ERROR', 'DEBUG', 'I
NFO', 'WARNING', 'CRITICAL', 'NOTSET' (default: default of

- ``loglevelmissingfiles``: int : one of the valid levels from
``logging``: 'WARN', 'ERROR', 'DEBUG', 'INFO', 'WARNING', 'CRITICAL',
'NOTSET' (default: ``logging.ERROR`` if
``failonmissingfiles = True``, else ``logging.WARN``)


For using interpolation, I strongly recomend *not* to use the default
PyYAML loader, as it sorts the dict entrys alphabetically, a fact that
may break interpolation in some cases (see ``test/odict.yaml`` and
``test/`` for an example). See Ordered Dict Yaml Loader /
Dumper aka. ODYLDo


The default jinja2.Environment for the interpolation is


hiyapyco.jinja2env = Environment(undefined=Undefined)

This means that undefined vars will be ignored and replaced with a empty

change the jinja2 Environment

If you like to change the jinja2 Environment used for the interpolation,
set ``hiyapyco.jinja2env`` **before** calling ``hiyapyco.load``!

use jinja2 DebugUndefined

If you like to keep the undefined var as string but raise no error, use


from jinja2 import Environment, Undefined, DebugUndefined, StrictUndefined
hiyapyco.jinja2env = Environment(undefined=DebugUndefined)

use jinja2 StrictUndefined

If you like to raise a error on undefined vars, use


from jinja2 import Environment, Undefined, DebugUndefined, StrictUndefined
hiyapyco.jinja2env = Environment(undefined=StrictUndefined)

This will raise a ``hiyapyco.HiYaPyCoImplementationException`` wrapped
arround the ``jinja2.UndefinedError`` pointing at the string causing the

more informations

`jinja2.Environment <>`__

cast interpolated strings

As you must use interpolation as strings (PyYAML will weep if you try to
start a value with ``{{``), you can set ``castinterpolated`` to *True*
in order to try to get a ``best match`` cast for the interpolated
values. **The ``best match`` cast is currently only a q&d implementation
and may not give you the expected results!**

Ordered Dict Yaml Loader / Dumper aka. ODYLDo

| This is a simple implementation of a PyYAML loader / dumper using
``OrderedDict`` from collections.
| **Because chaos is fun but order matters on loading dicts from a yaml
| In order to use this on python 2.6, please install ordereddict:


sudo pip-2.6 install ordereddict


From Source



git clone
cd hiyapyco
sudo python install


Download the latest or desired version of the source package from Unpack the archive and install by


sudo python install


Install the latest wheel package using:


pip install HiYaPyCo

debian packages


echo "deb ./" > /etc/apt/sources.list.d/hiyapyco.list
gpg --keyserver --recv-key ED7D414C
# or use:
wget -O - | gpg --import -
gpg --armor --export ED7D414C | apt-key add -
apt-get update
apt-get install python3-hiyapyco python-hiyapyco

rpm packages

use as URL for the yum repo and as the URL for the key.

Arch Linux

An `AUR package <>`__
is available.


(c) 2014 - 2016 Klaus Zerwes ` <>`__

| This package is free software.
| This software is licensed under the terms of the GNU GENERAL PUBLIC
LICENSE version 3 or later, as published by the Free Software
| See



Reverted: logger settings to initial state

Improved: dump

Merged: \* flatten mapping from Chris Petersen \* arch
linux package info from Peter Crighton


MERGED: fixes from mmariani


FIXED: issues #9 and #11


deb packages: \* removed support for python 2.6 \* include examples as


FIXED: issue #6 *import of hiyapyco **version** in causes pip
install failures*


Changed: moved to GPL

Improvements: missing files handling, doc


Implemented: ``castinterpolated``


Implemented: loading yaml docs from string


Improved tests and bool args checks

0.3.0 / 0.3.1

Implemented a Ordered Dict Yaml Loader


Fixed unicode handling

0.1.0 / 0.1.1

Initial release

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