ConfigCat Python SDK

Warnings

• breaking Version 10.0.0 dropped support for Python 2.7, 3.5, 3.6, and 3.7. Attempting to use the library on these versions will result in `ImportError` or other compatibility issues.
  Fix: Upgrade to Python 3.8 or newer. Ensure your CI/CD pipelines and deployment environments use a supported Python version.
• breaking Deprecated client initialization functions like `configcatclient.create_client()`, `create_client_with_auto_poll()`, etc., were removed in v8.0.0. The `stop()` method was also renamed to `close()`.
  Fix: Replace calls to removed `create_client` functions with `client = configcatclient.get(sdk_key)`. Update `client.stop()` calls to `client.close()`.
• breaking Version 9.0.0 introduced support for Config JSON v6 format. The older v5 format is no longer accepted for flag overrides, and the `User`'s `custom` dictionary now allows attribute values other than strings.
  Fix: If using local flag overrides, convert your config JSON files from v5 to v6 using the ConfigCat CLI tool. Update any code expecting `User` custom attributes to be strictly strings.
• gotcha It is strongly recommended to use the ConfigCat Client as a singleton object throughout your application. `configcatclient.get()` returns a singleton instance for a given SDK key.
  Fix: Initialize the client once at application startup using `client = configcatclient.get(SDK_KEY)` and reuse this instance across your application rather than creating new ones.
• gotcha Failure to explicitly close the ConfigCat client on application exit can lead to resource leaks (e.g., open HTTP connections, lingering background threads for polling).
  Fix: Ensure `client.close()` is called for individual clients, or `configcatclient.close_all()` is called to shut down all clients, typically in a `finally` block or application shutdown hook.
• gotcha Starting from v8.0.0, passing an invalid SDK key format to `configcatclient.get()` will raise a `ConfigCatClientException` unless the client is configured for local-only flag overrides.
  Fix: Validate your SDK key format (it's a 22-character string consisting of Latin letters, numbers, and hyphens) before passing it to `configcatclient.get()`, or handle `ConfigCatClientException` gracefully.

Install

• pip install configcat-client Install latest version

Imports

• configcatclient

  import configcatclient

• get

  client = configcatclient.get("#YOUR-SDK-KEY#")

  Deprecated client creation functions (e.g., `create_client`, `create_client_with_auto_poll`) were removed in v8.0.0. Use `configcatclient.get()` for singleton client instances.
• ConfigCatOptions

  from configcatclient import ConfigCatOptions

• PollingMode

  from configcatclient import PollingMode

• User

  from configcatclient import User

Quickstart

This quickstart demonstrates how to initialize the ConfigCat client, retrieve a feature flag's value, and safely close the client. It also shows how to get a value for a specific user using a `User` object. Remember to replace `YOUR_SDK_KEY_HERE` with your actual ConfigCat SDK Key, ideally loaded from an environment variable.

import os
import configcatclient

# Get your SDK Key from ConfigCat Dashboard (e.g., via environment variable)
SDK_KEY = os.environ.get('CONFIGCAT_SDK_KEY', 'YOUR_SDK_KEY_HERE')

def main():
    # Create a ConfigCat client instance (recommended as a singleton)
    client = configcatclient.get(SDK_KEY)

    # Get your setting value
    # The second argument is the default value if the key is not found
    is_my_awesome_feature_enabled = client.get_value('isMyAwesomeFeatureEnabled', False)

    if is_my_awesome_feature_enabled:
        print("Feature is ENABLED!")
    else:
        print("Feature is DISABLED.")

    # You can also get a value for a specific user
    user = configcatclient.User('some-user-id', email='user@example.com')
    is_feature_for_user = client.get_value('isMyAwesomeFeatureEnabled', False, user)
    print(f"Feature for user 'some-user-id': {is_feature_for_user}")

    # Stop ConfigCat client on application exit to release resources
    client.close()
    # Alternatively, configcatclient.close_all() to close all clients

if __name__ == '__main__':
    main()