https://github.com/zipfile/fiicha
A minimalistic feature flag implementation with type hints
https://github.com/zipfile/fiicha
Last synced: 7 months ago
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A minimalistic feature flag implementation with type hints
- Host: GitHub
- URL: https://github.com/zipfile/fiicha
- Owner: ZipFile
- License: bsd-2-clause
- Created: 2022-02-20T18:33:46.000Z (almost 4 years ago)
- Default Branch: master
- Last Pushed: 2022-02-22T21:44:33.000Z (almost 4 years ago)
- Last Synced: 2025-06-13T21:44:50.066Z (8 months ago)
- Language: Python
- Size: 17.6 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.rst
- License: LICENSE
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README
======
Fiicha
======
Fiicha is minimalistic mypy-friendly feature flag implementation with no
external dependencies.
Installation
============
.. code-block:: sh
pip install fiicha
For Development
---------------
Clone the repo, change current working dir to the root of the repo and execute:
.. code-block:: sh
python -m venv env
. env/bin/activate
pip install -e .[test,lint]
Usage
=====
Basic
-----
Basic usage is simple:
1. Sublcass from ``FeatureFlags``
2. Add ``FeatureFlag`` attributes representing individual feature flags.
.. code-block:: python
from fiicha import FeatureFlag, FeatureFlags
class MyProjectFeatureFlags(FeatureFlags):
release_x = FeatureFlag("Enable features from upcoming release X")
use_new_algorithm = FeatureFlag("Use new algorithm for ...")
ff = MyProjectFeatureFlags({"release_x": True})
print(ff.release_x) # True
print(ff.use_new_algorithm) # False
In addition, you kan specify a key defining default state of the feature flags:
.. code-block:: python
ff = MyProjectFeatureFlags({"all": True, "release_x": False}, default_key="all")
print(ff.release_x) # False
print(ff.use_new_algorithm) # True
Classes subclassed from ``FeatureFlags`` has full type hint support, so
when you are accessing removed or otherwise non-existent feature flags, you
can detect it before running tests:
.. code-block:: python
ff.xxx # will trigger mypy's attr-defined error
Utils
-----
The package comes with few util functions to avoid building your own framework
for simple use cases.
Single-line Configuration
~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
from fiicha import parse_feature_flags_string
flags_string = "release_x !use_new_algorithm" # stored in config
ff = MyProjectFeatureFlags(parse_feature_flags_string(flags_string))
print(ff.release_x) # True
print(ff.use_new_algorithm) # False
Load Flags From Environment Variables
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
import os
from fiicha import feature_flags_from_environ
os.environ["MYPROJ_FEATURE_RELEASE_X"] = "True" # can also be 1, t, yes, on
os.environ["MYPROJ_FEATURE_USE_NEW_ALGORITHM"] = "False" # can also be 0, f, no, off or empty string
ff = MyProjectFeatureFlags(feature_flags_from_environ("MYPROJ_FEATURE_"))
print(ff.release_x) # True
print(ff.use_new_algorithm) # False
Automatically Document Your Feature Flags
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
from fiicha import make_napoleon_doc, make_sphinx_doc
class GoogleStyleDocFeatureFlags(FeatureFlags, make_doc=make_napoleon_doc):
a = FeatureFlag("Enable feature A")
b = FeatureFlag("Enable feature B")
class SphinxStyleDocFeatureFlags(FeatureFlags, make_doc=make_sphinx_doc):
x = FeatureFlag("Enable feature X")
y = FeatureFlag("Enable feature Y")
print(GoogleStyleDocFeatureFlags.__doc__)
print(SphinxStyleDocFeatureFlags.__doc__)
Context Variable Support
~~~~~~~~~~~~~~~~~~~~~~~~
You might want to do A/B testing or otherwise toggle feature flags for
individual users without affecting the rest of the system. For such cases,
there is ``FeatureFlagsContext`` - a wrapper around ``ContextVar``. It copies
current feature flags and sets them as new context variable on enter and
resets them back on exit. This way you will be able to achieve global feature
flags protection from changes made within context of a request or a task.
.. code-block:: python
from contextvars import ContextVar
from fiicha import FeatureFlag, FeatureFlags, FeatureFlagsContext
class MyFeatureFlags(FeatureFlags):
a = FeatureFlag("Enable feature A")
b = FeatureFlag("Enable feature B")
root = MyFeatureFlags()
var: ContextVar[MyFeatureFlags] = ContextVar("test", default=root)
ff_ctx = FeatureFlagsContext(var)
with ff_ctx:
ff = var.get()
ff.a = True
assert ff is not root # is a copy
assert not root.a # not changed
Advanced
--------
See ``examples`` subfolder within the repo.