mitol-django-olposthog 2026.4.2

MIT Open Learning django app extensions for Posthog.

mitol-django-olposthog

This is the Open Learning OlPosthog app. It provides an API to interact with Posthog in order to check feature flags.

Installation and setup

Add the OlPosthog app:

docker-compose run -u root --rm web uv add mitol-django-olposthog

Add the following to the ready() method for your App.

from mitol.olposthog.features import configure
configure()

Common Django settings

• HOSTNAME - The website's hostname.

OlPosthog app settings

All settings for the mitol-django-olposthog app are prefaced with 'POSTHOG'.

• POSTHOG_ENABLED - True in order to enable Posthog feature flags in the application. False to disable Posthog feature flags.
• POSTHOG_PROJECT_API_KEY - Required if POSTHOG_ENABLED is True. Private API key to communicate with PostHog.
• POSTHOG_PERSONAL_API_KEY - Optional. Personal API key for local flag evaluation. When set, the PostHog SDK evaluates flags locally without making a per-request HTTP call. Recommended for production to reduce latency and cost.
• POSTHOG_API_HOST - Required if POSTHOG_ENABLED is True. Host URL for the PostHog API.
• POSTHOG_FEATURE_FLAG_REQUEST_TIMEOUT_MS - Timeout (ms) for PostHog feature flag requests. Default: 3000.
• POSTHOG_MAX_RETRIES - Number of times requests to PostHog should be retried after failing. Default: 3.
• POSTHOG_POLL_INTERVAL - Seconds between PostHog flag config polling. Only relevant when POSTHOG_PERSONAL_API_KEY is set for local evaluation. Default: 300.

Circuit breaker

The circuit breaker protects your application when PostHog is slow or unreachable. If a PostHog request takes longer than the trip threshold, the circuit opens and subsequent calls return immediately from settings.FEATURES (your local fallback) until the cooldown expires.

• POSTHOG_CIRCUIT_BREAKER_TRIP_THRESHOLD_SECONDS - How long a PostHog request can take before the circuit trips. Default: 6.
• POSTHOG_CIRCUIT_BREAKER_COOLDOWN_SECONDS - How long the circuit stays open before PostHog is retried. Default: 60.

The circuit breaker applies to both is_enabled() and get_all_feature_flags().

Note: The circuit breaker is most relevant when POSTHOG_PERSONAL_API_KEY is not set (remote evaluation). With local evaluation enabled, flag checks are served from an in-process cache populated by a background polling thread, so per-request HTTP calls — and therefore circuit-breaker trips — are rare.

Cache table creation

Add the following cache defintion to your CACHES in the settings.py file of your Django application.

CACHES = {
  "durable": {
      "BACKEND": "django.core.cache.backends.db.DatabaseCache",
      "LOCATION": "durable_cache",
  },
}

You must create the cache included in this library. This can be done by running the following command from within the Django application that this library is being added to: ./manage.py createcachetable.

Usage

Check single feature flag value

You can check the value of a feature flag on Posthog with the following code:

from mitol.olposthog.features import is_enabled
is_enabled(<FEATURE_FLAG_NAME>)

This will return a boolean value based on whether the Posthog feature flag is True or False.

Retrieve all feature flags from Posthog

You can retrieve all the feature flags from Posthog using:

from mitol.olposthog.features import get_all_feature_flags
get_all_feature_flags()