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OpenFeature Provider

OpenFeature is an open standard that provides a vendor-agnostic, community-driven API for feature flagging that works with DevCycle.

DevCycle provides a Python implementation of the OpenFeature Provider interface, if you prefer to use the OpenFeature API.

GitHub

Usage​

Installation​

Install the OpenFeature Python SDK and DevCycle Provider:

$ pip install devcycle-python-server-sdk

(you may need to run pip with root permission: sudo pip install devcycle-python-server-sdk)

Getting Started​

Initialize the DevCycle SDK and set the DevCycleProvider as the provider for OpenFeature:

from devcycle_python_sdk import DevCycleLocalClient, DevCycleLocalOptions
from devcycle_python_sdk.models.user import DevCycleUser
from openfeature import api
from openfeature.evaluation_context import EvaluationContext

# Create an options object to do custom configurations, or use the defaults
options = DevCycleLocalOptions()

# create an instance of the DevCycleLocalClient class
devcycle_client = DevCycleLocalClient('<DEVCYCLE_SERVER_SDK_KEY>', options)

# set the provider for OpenFeature
api.set_provider(devcycle_client.get_openfeature_provider())

# get the OpenFeature client
open_feature_client = api.get_client()

Evaluate a Variable​

Use a Variable value by setting the EvaluationContext, then passing the Variable key and default value to one of the OpenFeature flag evaluation methods.

context = EvaluationContext(
        targeting_key="test-1234",
        attributes={
            "email": "[email protected]",
            "name": "Test User",
        },
    )
open_feature_client.context = context

flag_value = client.get_boolean_value("boolean_flag", False)

Required Targeting Key​

For the DevCycle SDK to work we require either a targeting_key or user_id to be set on the OpenFeature context. This is used to identify the user as the user_id for a DevCycleUser in DevCycle.

Context properties to DevCycleUser​

The provider will automatically translate known DevCycleUser properties from the OpenFeature context to the DevCycleUser object. DevCycleUser Python Interface

For example all these properties will be set on the DevCycleUser:

# Pass context when querying values from the OpenFeature client
context = EvaluationContext(
        targeting_key="test-1234",
        attributes={
            "email": "[email protected]",
            "name": "Test User",
            "language": "en",
            "country": "CA",
            "appVersion": "1.0.11",
            "appBuild": 1000,
			"deviceModel": "Macbook",
            "customData": {"custom": "data"},
            "privateCustomData": {"private": "data"},
        },
    )
# Or set on the client with:
open_feature_client.context = context

Context properties that are not known DevCycleUser properties will be automatically added to the CustomData property of the DevCycleUser.

Context Limitations​

DevCycle only supports flat JSON Object properties used in the Context. Non-flat properties will be ignored.

For example obj will be ignored:

context = EvaluationContext(
        targeting_key="test-1234",
        attributes={
            "obj": {"key": "value"},
        },
    )
openfeature.NewEvaluationContext(
    "user_id",
    map[string]interface{}{
        "obj": map[string]interface{}{"key": "value"},
    },
)

JSON Flag Limitations​

The OpenFeature spec for JSON flags allows for any type of valid JSON value to be set as the flag value.

For example the following are all valid default value types to use with OpenFeature:

# Invalid JSON values for the DevCycle SDK, will return defaults
open_feature_client.get_object_value("json-flag", ["list"], context)
open_feature_client.get_object_value("json-flag", 610, context)
open_feature_client.get_object_value("json-flag", False, context)
open_feature_client.get_object_value("json-flag", "string", context)
open_feature_client.get_object_value("json-flag", None, context)

However, these are not valid types for the DevCycle SDK, the DevCycle SDK only supports JSON Objects:

# Valid JSON Object as the default value, will be evaluated by the DevCycle SDK
open_feature_client.get_object_value("json-flag", {"default": "value"}, context)