interpolatr 0.0.2

Interpolation tool

interpolatr
===========

Interpolatr is a command line tool and library for interpolating
configuration settings into templatized files. It uses the
`jinja2 <http://jinja.pocoo.org/docs/2.9/>`_ library for templating.

Usage
-----

The ``interpolatr`` command-line tool currently supports two
configuration sources (command line and YAML; see below) and a single
template sink ( file-based jinja2 templates). However, it is easy to
supply your own configuration sources or template sinks if necessary.

Usage:

::

interpolatr [OPTIONS] [<config-class> <config-args>]... [<supplier-class> <supplier-args>]...

For example, using builtin config and template suppliers:

::

interpolatr -D override_setting=value YamlConfigSource --path conf.yaml ExtensionFileSinkSupplier --target_dir root

Configuration Sources
~~~~~~~~~~~~~~~~~~~~~

There are currently two built-in configuration sources for
``interpolatr``:

1. *Command line*: You can specify configuration values when calling
``interpolatr`` using the ``-D`` flag: ``interpolator -D foo=bar``.

2. *YAML*: You can specify configuration values in a hierarchical
``yaml`` format.

The format looks like this: \`\`\`yaml settings: setting\_name:
setting\_value setting\_two: other\_value

Optional files to inherit settings from
=======================================

base: - file/to/inherit-from.yml

::

# Functionally, this is no different than flattening the list out
- [ some/more.yaml, and-even-more.yml ]

- final-base-file.yml

\`\`\`

These settings are populated into a ``ChainedMap``, so any settings
missing in your top-level configuration will be pulled from its
parent(s).

It is simple to define your own configuration sources: see
``config.py``. If using the command line, you can use a custom config
source by specifying the fully qualified class path on the command line.

Configuration Sinks
~~~~~~~~~~~~~~~~~~~

Configuration values can currently be written into templatized
configuration files. The templating is powered by ``jinja2``, so you may
use any valid ``jinja2`` expressions to define your configuration files.

It should be straightfoward to customize this process as well; see the
code in ``sink.py`` for reference.

Notes
-----

- This was developed under Python 2.7, but at least gives the
appearance of working under Python 3.
- This is an early version of this tool, so the interfaces are subject
to change.

Copyright and License
---------------------

Copyright 2017, Yahoo Inc.

Licensed under the terms of the Apache License, Version 2.0. See the
LICENSE file associated with the project for terms.