python-sdk/open_feature/open_feature_client.py

271 lines
8.6 KiB
Python

import logging
import typing
from numbers import Number
from open_feature.evaluation_context.evaluation_context import EvaluationContext
from open_feature.exception.exceptions import GeneralError
from open_feature.flag_evaluation.flag_evaluation_details import FlagEvaluationDetails
from open_feature.flag_evaluation.flag_type import FlagType
from open_feature.flag_evaluation.reason import Reason
from open_feature.hooks.hook import Hook
from open_feature.hooks.hook_context import HookContext
from open_feature.hooks.hook_support import (
after_all_hooks,
after_hooks,
before_hooks,
error_hooks,
)
from open_feature.open_feature_evaluation_context import api_evaluation_context
from open_feature.provider.no_op_provider import NoOpProvider
from open_feature.provider.provider import AbstractProvider
class OpenFeatureClient:
def __init__(
self,
name: str,
version: str,
context: EvaluationContext = None,
hooks: typing.List[Hook] = None,
provider: AbstractProvider = None,
):
self.name = name
self.version = version
self.context = context or EvaluationContext()
self.hooks = hooks or []
self.provider = provider
def add_hooks(self, hooks: typing.List[Hook]):
self.hooks = self.hooks + hooks
def get_boolean_value(
self,
key: str,
default_value: bool,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> bool:
return self.evaluate_flag_details(
FlagType.BOOLEAN,
key,
default_value,
evaluation_context,
flag_evaluation_options,
).value
def get_boolean_details(
self,
key: str,
default_value: bool,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> FlagEvaluationDetails:
return self.evaluate_flag_details(
FlagType.BOOLEAN,
key,
default_value,
evaluation_context,
flag_evaluation_options,
)
def get_string_value(
self,
key: str,
default_value: str,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> str:
return self.evaluate_flag_details(
FlagType.STRING,
key,
default_value,
evaluation_context,
flag_evaluation_options,
).value
def get_string_details(
self,
key: str,
default_value: str,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> FlagEvaluationDetails:
return self.evaluate_flag_details(
FlagType.STRING,
key,
default_value,
evaluation_context,
flag_evaluation_options,
)
def get_number_value(
self,
key: str,
default_value: Number,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> Number:
return self.evaluate_flag_details(
FlagType.NUMBER,
key,
default_value,
evaluation_context,
flag_evaluation_options,
).value
def get_number_details(
self,
key: str,
default_value: Number,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> FlagEvaluationDetails:
return self.evaluate_flag_details(
FlagType.NUMBER,
key,
default_value,
evaluation_context,
flag_evaluation_options,
)
def get_object_value(
self,
key: str,
default_value: dict,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> dict:
return self.evaluate_flag_details(
FlagType.OBJECT,
key,
default_value,
evaluation_context,
flag_evaluation_options,
).value
def get_object_details(
self,
key: str,
default_value: dict,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> FlagEvaluationDetails:
return self.evaluate_flag_details(
FlagType.OBJECT,
key,
default_value,
evaluation_context,
flag_evaluation_options,
)
def evaluate_flag_details(
self,
flag_type: FlagType,
key: str,
default_value: typing.Any,
evaluation_context: EvaluationContext = None,
flag_evaluation_options: typing.Any = None,
) -> FlagEvaluationDetails:
"""
Evaluate the flag requested by the user from the clients provider.
:param flag_type: the type of the flag being returned
:param key: the string key of the selected flag
:param default_value: backup value returned if no result found by the provider
:param evaluation_context: Information for the purposes of flag evaluation
:param flag_evaluation_options: Additional flag evaluation information
:return: a FlagEvaluationDetails object with the fully evaluated flag from a
provider
"""
if evaluation_context is None:
evaluation_context = EvaluationContext()
hook_context = HookContext(
flag_key=key,
flag_type=flag_type,
default_value=default_value,
evaluation_context=evaluation_context,
client_metadata=None,
provider_metadata=None,
)
merged_hooks = []
try:
# https://github.com/open-feature/spec/blob/main/specification/sections/03-evaluation-context.md
# Any resulting evaluation context from a before hook will overwrite
# duplicate fields defined globally, on the client, or in the invocation.
invocation_context = before_hooks(
flag_type, hook_context, merged_hooks, None
)
invocation_context.merge(ctx2=evaluation_context)
# merge of: API.context, client.context, invocation.context
merged_context = (
api_evaluation_context().merge(self.context).merge(invocation_context)
)
flag_evaluation = self.create_provider_evaluation(
flag_type,
key,
default_value,
merged_context,
)
after_hooks(type, hook_context, flag_evaluation, merged_hooks, None)
return flag_evaluation
# Catch any type of exception here since the user can provide any exception
# in the error hooks
except Exception as e: # noqa
error_hooks(flag_type, hook_context, e, merged_hooks, None)
return FlagEvaluationDetails(
key=key,
value=default_value,
reason=Reason.ERROR,
error_code=e.error_message,
)
finally:
after_all_hooks(flag_type, hook_context, merged_hooks, None)
def create_provider_evaluation(
self,
flag_type: FlagType,
key: str,
default_value: typing.Any,
evaluation_context: EvaluationContext = None,
) -> FlagEvaluationDetails:
"""
Encapsulated method to create a FlagEvaluationDetail from a specific provider.
:param flag_type: the type of the flag being returned
:param key: the string key of the selected flag
:param default_value: backup value returned if no result found by the provider
:param evaluation_context: Information for the purposes of flag evaluation
:return: a FlagEvaluationDetails object with the fully evaluated flag from a
provider
"""
args = (
key,
default_value,
evaluation_context,
)
if not self.provider:
logging.info("No provider configured, using no-op provider.")
self.provider = NoOpProvider()
get_details_callable = {
FlagType.BOOLEAN: self.provider.get_boolean_details,
FlagType.NUMBER: self.provider.get_number_details,
FlagType.OBJECT: self.provider.get_object_details,
FlagType.STRING: self.provider.get_string_details,
}.get(flag_type)
if not get_details_callable:
raise GeneralError(error_message="Unknown flag type")
return get_details_callable(*args)