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python-anyconfig

Introduction

python-anyconfig [1] is a MIT licensed python library provides generic access to configuration files in various formats with configuration merge along with config template and schema validation/generation support.

I, Satoru SATOH <ssato@redhat.com>, originally developed and keep maintain it with others’ help [2] .

[1]This name took an example from the ‘anydbm’ python standard library.
[2]see the output of git log –pretty=format:”%an %ae” | grep -vE “Satoru SATOH” | sort | uniq.

Features

python-anyconfig provides very simple and unified APIs to process configuration files in various formats:

  • anyconfig.load() to load configuration files and return a dict-like object represents loaded configuration
  • anyconfig.loads() to load configuration from a string just like json.loads does
  • anyconfig.dump() to dump a configuration file from a dict or dict-like object represents configuration
  • anyconfig.dumps() to dump a configuration string from a dict or dict-like object represents configuration
  • anyconfig.validate() to validate configuration loaded with anyconfig.load() with JSON schema [3] (object) also loaded with anyconfig.load(). anyconfig.load() may help loading JSON schema file[s] in any formats anyconfig supports.
  • anyconfig.gen_schema() to generate a minimum JSON schema object to validate given configuration file[s] later.

It enables to load configuration file[s] in various formats in the same manner, and in some cases, even there is no need to take care of the actual format of configuration file[s] like the followings:

import anyconfig

# Config type (format) is automatically detected by filename (file
# extension) in some cases.
conf1 = anyconfig.load("/path/to/foo/conf.d/a.yml")

# Loaded config data is a dict-like object, for example:
#
#   conf1["a"] => 1
#   conf1["b"]["b1"] => "xyz"
#   conf1["c"]["c1"]["c13"] => [1, 2, 3]

# Or you can specify the format (config type) explicitly if automatic
# detection may not work.
conf2 = anyconfig.load("/path/to/foo/conf.d/b.conf", "yaml")

# Specify multiple config files by the list of paths. Configurations of each
# files are merged.
conf3 = anyconfig.load(["/etc/foo.d/a.json", "/etc/foo.d/b.json"])

# Similar to the above but all or one of config file[s] is/are missing:
conf4 = anyconfig.load(["/etc/foo.d/a.json", "/etc/foo.d/b.json"],
                       ignore_missing=True)

# Specify config files by glob path pattern:
conf5 = anyconfig.load("/etc/foo.d/*.json")

# Similar to the above, but parameters in the former config file will be simply
# overwritten by the later ones:
conf6 = anyconfig.load("/etc/foo.d/*.json", ac_merge=anyconfig.MS_REPLACE)

Also, it can process configuration files which are actually jinja2-based template files:

  • Enables to load a substantial configuration rendered from half-baked configuration template files with given context
  • Enables to load a series of configuration files indirectly ‘include’-d from a/some configuration file[s] with using jinja2’s ‘include’ directive.
In [1]: import anyconfig

In [2]: open("/tmp/a.yml", 'w').write("a: {{ a|default('aaa') }}\n")

In [3]: anyconfig.load("/tmp/a.yml", ac_template=True)
Out[3]: {'a': 'aaa'}

In [4]: anyconfig.load("/tmp/a.yml", ac_template=True, ac_context=dict(a='bbb'))
Out[4]: {'a': 'bbb'}

In [5]: open("/tmp/b.yml", 'w').write("{% include 'a.yml' %}\n")  # 'include'

In [6]: anyconfig.load("/tmp/b.yml", ac_template=True, ac_context=dict(a='ccc'))
Out[6]: {'a': 'ccc'}

And python-anyconfig enables to validate configuration files in various format with using JSON schema like the followings:

# Validate a JSON config file (conf.json) with JSON schema (schema.yaml).
# If validatation suceeds, `rc` -> True, `err` -> ''.
conf1 = anyconfig.load("/path/to/conf.json")
schema1 = anyconfig.load("/path/to/schema.yaml")
(rc, err) = anyconfig.validate(conf1, schema1)  # err is empty if success, rc == 0

# Validate a config file (conf.yml) with JSON schema (schema.yml) while
# loading the config file.
conf2 = anyconfig.load("/a/b/c/conf.yml", ac_schema="/c/d/e/schema.yml")

# Validate config loaded from multiple config files with JSON schema
# (schema.json) while loading them.
conf3 = anyconfig.load("conf.d/*.yml", ac_schema="/c/d/e/schema.json")

# Generate jsonschema object from config files loaded and get string
# representation.
conf4 = anyconfig.load("conf.d/*.yml")
scm4 = anyconfig.gen_schema(conf4)
scm4_s = anyconfig.dumps(scm4, "json")

And in the last place, python-anyconfig provides a CLI tool called anyconfig_cli to process configuration files and:

  • Convert a/multiple configuration file[s] to another configuration files in different format
  • Get configuration value in a/multiple configuration file[s]
  • Validate configuration file[s] with JSON schema
  • Generate minimum JSON schema file to validate given configuration file[s]
[3]http://json-schema.org

Supported configuration formats

python-anyconfig supports various (configuration) file formats if the required module is available and the corresponding backend is ready to use:

Supported formats
Format Type Requirement Notes
JSON json json (standard lib) or simplejson [4] Enabled by default.
Ini-like ini configparser (standard lib) Ditto.
Java properties [5] properties None (native implementation with standard lib) Ditto.
XML xml lxml [6] or ElementTree Ditto.
YAML yaml PyYAML [7] Enabled automatically if the left requirement is satisfied.
ConifgObj configobj configobj [8] Ditto.
MessagePack msgpack msgpack-python [9] Ditto.
TOML toml toml [10] Ditto.
BSON bson bson in pymongo [11] Ditto.

The supported formats of python-anyconfig on your system is able to be listed by ‘anyconfig_cli -L’ like this:

$ anyconfig_cli -L
Supported config types: bson, configobj, ini, json, msgpack, toml, xml, yaml
$

or with the API ‘anyconfig.list_types()’ will show them:

In [8]: anyconfig.list_types()
Out[8]: ['bson', 'configobj', 'ini', 'json', 'msgpack', 'toml', 'xml', 'yaml']

In [9]:

It utilizes plugin mechanism provided by setuptools [12] and other formats may be supported by corresponding pluggale backends like the following:

See also How to write backend plugin modules section about writing plugins.

[4]https://pypi.python.org/pypi/simplejson
[5]ex. https://docs.oracle.com/javase/7/docs/api/java/util/Properties.html
[6]https://pypi.python.org/pypi/PyYAML
[7]https://pypi.python.org/pypi/lxml
[8]https://pypi.python.org/pypi/configobj
[9]https://pypi.python.org/pypi/msgpack-python
[10]https://pypi.python.org/pypi/toml
[11]https://pypi.python.org/pypi/pymongo
[12]http://peak.telecommunity.com/DevCenter/setuptools#dynamic-discovery-of-services-and-plugins
[13]https://pypi.python.org/pypi/pyjavaproperties

Installation

Requirements

Many runtime dependencies are resolved dynamically and python-anyconfig just disables specific features if required dependencies are not satisfied. Therefore, only python standard library is required to install and use python-anyconfig at minimum.

The following packages need to be installed along with python-anycofig to enable the features.

Feature Requirements Notes
YAML load/dump PyYAML none
ConifgObj load/dump configobj none
MessagePack load/dump msgpack-python none
TOML load/dump toml none
BSON load/dump bson bson from pymongo package may work and bson [14] does not
Template config Jinja2 [15] none
Validation with JSON schema jsonschema [16] Not required to generate JSON schema.
[14]https://pypi.python.org/pypi/bson/
[15]https://pypi.python.org/pypi/Jinja2/
[16]https://pypi.python.org/pypi/jsonschema/

How to install

There is a couple of ways to install python-anyconfig:

  • Binary RPMs:

    If you’re Fedora or Red Hat Enterprise Linux user, you can install RPMs from the copr repository, http://copr.fedoraproject.org/coprs/ssato/python-anyconfig/.

  • PyPI: You can install python-anyconfig from PyPI with using pip:

    $ pip install anyconfig

  • Build RPMs from source: It’s easy to build python-anyconfig with using rpm-build and mock:

    $ python setup.py srpm && mock dist/python-anyconfig-<ver_dist>.src.rpm

    or:

    $ python setup.py rpm

    and install built RPMs.

  • Build from source: Of course you can build and/or install python modules in usual way such like ‘python setup.py bdist’, ‘pip install git+https://github.com/ssato/python-anyconfig/’ and so on.

Help and feedbak

If you have any issues / feature request / bug reports with python-anyconfig, please open an issue ticket on github.com (https://github.com/ssato/python-anyconfig/issues).

The following areas are still insufficient, I think.

  • Make python-anyconfig robust for invalid inputs
  • Make python-anyconfig scaled: some functions are limited by max recursion depth.
  • Documentation:
    • Especially API docs need more fixes and enhancements! CLI doc is non-fulfilling also.
    • English is not my native lang and there are many wrong and hard-to-understand expressions.

Any feedbacks, helps, suggestions are welcome! Please open github issues for these kind of problems also!

Hacking

How to test

Run ‘[WITH_COVERAGE=1] ./pkg/runtest.sh [path_to_python_code]’ or ‘tox’ for tests.

About test-time requirements, please take a look at pkg/test_requirements.txt.

How to write backend plugin modules

Backend class must inherit anyconfig.backend.base.Parser or its children in anyconfig.backend.base module and need some members and methods such as load_from_string(), load_from_path(), load_from_stream(), dump_to_string(), dump_to_path() and dump_to_stream(). And anyconfig.backend.tests.ini.Test10 and anyconfig.backend.tests.ini.Test20 may help to write test cases of these methods.

JSON and YAML backend modules (anyconfig.backend.{json,yaml}_) should be good examples to write backend modules and its test cases, I think.

Also, please take a look at some example backend plugin modules mentioned in the Supported configuration formats section.

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