Integrate Flagsmith with Sentry to enable tracking suspect feature flag changes:

• Change Tracking logs when feature flags update in Flagsmith, helping correlate flag changes with new errors or regressions.
• Evaluation Tracking captures feature flag evaluation in the code, adding their state to Issue details and allowing for flag-based Issue search.

Change Tracking setup

1. In Sentry
   1. Visit the feature flags settings page in a new tab.
   2. Click the "Add New Provider" button.
   3. Select "Generic" in the dropdown that says "Select a provider".
   4. Copy the provided Sentry webhook URL — we'll use that soon.
   5. Do not close this page! We're not done yet.
2. In Flagsmith
   1. Go to Integrations > Sentry > Add Integration.
   2. Choose the Environment from which Sentry will receive feature flag change events.
   3. Paste the URL copied above into "Sentry webhook URL".
   4. Insert a secret (10-60 characters) and copy it.
   5. Click "Save". ✅
3. Back to Sentry
   1. Paste the secret copied above.
   2. Click "Add Provider". ✅

Flag change events should now be sent to Sentry, and displayed in Issue details. For more information, visit Sentry's Issue Details page documentation.

Evaluation Tracking setup

Flagsmith relies on the OpenFeature SDK and its integration with Sentry in order to add evaluated feature flags to a Sentry issue when it occurs. Learn more by reading OpenFeature's SDK docs and provider docs.

Python

Sentry offers good documentation on how to integrate the Sentry SDK with the OpenFeature SDK in Python. We'll extend it a bit adding an example of using it with Flagsmith.

You'll need to install the following libraries:

pip install "sentry-sdk[openfeature]" openfeature-provider-flagsmith

The following snippet is a micro-application that reports feature flags to Sentry when an exception is raised.

import flagsmith
import sentry_sdk
from openfeature import api as of_api
from openfeature_flagsmith.provider import FlagsmithProvider
from sentry_sdk.integrations.openfeature import OpenFeatureIntegration

app = flask.Flask(__name__)

flagsmith_client = flagsmith.Flagsmith(
    environment_key='<public environment key>',
)

feature_flag_provider = FlagsmithProvider(
    client=flagsmith_client,
)

of_api.set_provider(feature_flag_provider)

sentry_sdk.init(
    dsn="<Sentry DSN>",
    send_default_pii=True,
    integrations=[
        OpenFeatureIntegration(),
    ]
)

def apply_discount(price):
    of_client = of_api.get_client()
    is_discount_enabled = of_client.get_boolean_value('discount_enabled', False)
    if is_discount_enabled:
        discount = price / 0  # ZeroDivisionError
    else:
        discount = None
    return price * discount  # TypeError

JavaScript

Sentry offers good documentation on how to integrate the Sentry SDK with the OpenFeature SDK in JavaScript. We'll extend it a bit adding an example of using it with Flagsmith.

You'll need to install the following libraries:

npm install @sentry/browser @openfeature/web-sdk @openfeature/flagsmith-client-provider

The following snippet extends Sentry's example with the Flagsmith provider:

import * as Sentry from '@sentry/browser';
import { FlagsmithClientProvider } from '@openfeature/flagsmith-client-provider';
import { OpenFeature } from '@openfeature/web-sdk';

Sentry.init({
 dsn: '___PUBLIC_DSN___',
 integrations: [Sentry.openFeatureIntegration()],
});

const flagsmithClientProvider = new FlagsmithClientProvider({
 environmentID: '<FLAGSMITH_CLIENT_SIDE_ENVIRONMENT_KEY>',
});
OpenFeature.setProvider(flagsmithClientProvider);

OpenFeature.addHooks(new Sentry.OpenFeatureIntegrationHook());

const client = OpenFeature.getClient();
const result = client.getBooleanValue('test-flag', false); // evaluate with a default value
Sentry.captureException(new Error('Something went wrong!'));

Alternatively, the Flagsmith SDK can be initialized with Sentry without OpenFeature:

import * as Sentry from '@sentry/browser';
import flagsmith from 'flagsmith';

Sentry.init({
 dsn: '___PUBLIC_DSN___',
 // ...
});

flagsmith.init({
 environmentID: '<FLAGSMITH_CLIENT_SIDE_ENVIRONMENT_KEY>',
 // ...
 sentryClient: Sentry.getClient(),
});

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You can learn more about feature flags and Sentry issues in their Issue Details documentation.