OpenFeature (Python)

PostHog provides an official OpenFeature provider for Python, so you can evaluate PostHog feature flags through the standard OpenFeature API.

Package: openfeature-provider-posthog
Import path: openfeature.contrib.provider.posthog

Installation

Terminal
pip install openfeature-provider-posthog

This installs posthog and openfeature-sdk as dependencies.

Usage

Construct and configure a PostHog client, then register the provider with the OpenFeature SDK:

Python
import posthog
from openfeature import api
from openfeature.evaluation_context import EvaluationContext
from openfeature.contrib.provider.posthog import PostHogProvider

client = posthog.Posthog("<ph_project_api_key>", host="https://us.i.posthog.com")

# personal_api_key="<ph_personal_api_key>" enables local evaluation
api.set_provider(PostHogProvider(client, default_distinct_id="anonymous"))

of_client = api.get_client()

context = EvaluationContext(
    targeting_key="user_distinct_id",
    attributes={"plan": "pro"},
)

is_enabled = of_client.get_boolean_value("my-flag", False, context)

You own the PostHog client lifecycle — call client.shutdown() when your app exits.

Evaluation context

The OpenFeature evaluation context maps to PostHog's flag evaluation inputs:

OpenFeature context	PostHog
`targeting_key`	`distinct_id` (required unless `default_distinct_id` is set)
`groups` attribute	groups
`group_properties` attribute	group properties
any other attribute	person properties

If no targeting_key is present and no default_distinct_id is configured, the provider returns your default value with error_code = TARGETING_KEY_MISSING.

Supported flag types

OpenFeature method	Resolves to
`get_boolean_value`	whether the flag is enabled
`get_string_value`	the multivariate variant key
`get_integer_value` / `get_float_value`	the variant parsed as a number
`get_object_value`	the flag's JSON payload

Calling a typed getter on an incompatible flag (for example get_string_value on a boolean flag) returns your default value with error_code = TYPE_MISMATCH, per the OpenFeature spec.

Options

PostHogProvider(client, *, default_distinct_id=None, send_feature_flag_events=True)

default_distinct_id — distinct ID used when the context has no targeting_key. Defaults to None (raise TARGETING_KEY_MISSING).
send_feature_flag_events — whether to emit $feature_flag_called events on each evaluation. Defaults to True.