philiprehberger-feature-flag 0.2.1

Simple feature flags with percentage rollout and user targeting.

philiprehberger-feature-flag

Simple feature flags with percentage rollout and user targeting.

Installation

pip install philiprehberger-feature-flag

Usage

Basic flags

from philiprehberger_feature_flag import flags

flags.load({"dark_mode": True, "beta_ui": False})

if flags.is_enabled("dark_mode"):
    enable_dark_mode()

Percentage rollout

flags.load({
    "new_checkout": {
        "enabled": True,
        "rollout": 25,  # 25% of users
    }
})

if flags.is_enabled("new_checkout", user_id="user-42"):
    show_new_checkout()

User targeting

flags.load({
    "admin_panel": {
        "enabled": True,
        "users": ["alice", "bob"],
    }
})

if flags.is_enabled("admin_panel", user_id="alice"):
    show_admin_panel()

Load from JSON file

flags.load("flags.json")

Load from environment variables

# Set FF_DARK_MODE=true, FF_BETA=0, etc.
flags.load()  # reads FF_* env vars

Runtime overrides

flags.override("beta_ui", True)   # force-enable for testing
flags.reset()                     # clear all overrides

Change callbacks

def on_flag_change(name, old, new):
    print(f"Flag {name} changed from {old} to {new}")

flags.on_change(on_flag_change)
flags.load({"dark_mode": True})
# prints: Flag dark_mode changed from None to True

Flag groups

flags.load({
    "ui_dark_mode": True,
    "ui_sidebar": False,
    "api_rate_limit": 100,
})

ui_flags = flags.group("ui_")
# {"ui_dark_mode": True, "ui_sidebar": False}

API

Function / Method	Description
FlagStore()	Create a new flag store
store.load(config)	Load flags from dict, JSON file path, or env vars (None)
store.is_enabled(name, **context)	Check if a flag is enabled
store.all()	Return all loaded flags as a dict
store.override(name, value)	Set a runtime override
store.reset()	Clear all runtime overrides
store.on_change(callback)	Register a callback fired as callback(flag_name, old_value, new_value) on changes
store.group(prefix)	Return dict of flags whose name starts with prefix with resolved values
flags	Module-level FlagStore instance

Development

pip install -e .
python -m pytest tests/ -v

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License

MIT