grafana/contribute/feature-toggles.md

Feature toggle guide

This guide helps you to add your feature behind a feature flag, code that lets you enable or disable a feature without redeploying Grafana.

Steps to adding a feature toggle

1. Define the feature toggle in registry.go. To see what each feature stage means, look at the related comments. If you are a community member, use the CODEOWNERS file to determine which team owns the package you are updating.
2. Run the Go tests mentioned at the top of this file. This generates all the additional files needed: toggles_gen for the backend, grafana-data for the frontend, and docs. To run the test, run make gen-feature-toggles.

How to use the toggle in your code

Once your feature toggle is defined, you can then wrap your feature around a check if the feature flag is enabled on that Grafana instance.

Examples:

• Backend: Use the IsEnabled function and pass in your feature toggle.

Frontend

Use the new OpenFeature-based feature flag client for all new feature flags. There are some differences compared to the legacy config.featureToggles system:

• Feature flag initialisation is async, but will be finished by the time the UI is rendered. This means you cannot get the value of a feature flag at the 'top level' of a module/file
• Call evaluateBooleanFlag("flagName") from @grafana/runtime/internal instead to get the value of a feature flag
• Feature flag values may change over the lifetime of the session. Do not store the value in a variable that is used for longer than a single render - always call evaluateBooleanFlag lazily when you use the value.

e.g.

import { evaluateBooleanFlag } from '@grafana/runtime/internal';

// BAD - Don't do this. The feature toggle will not evaluate correctly
const isEnabled = evaluateBooleanFlag('newPreferences', false);

function makeAPICall() {
  // GOOD - The feature toggle should be called after app initialisation
  if (evaluateBooleanFlag('newPreferences', false)) {
    // do new things
  }
}

Enabling toggles in development

Add the feature toggle to the feature_toggle section in your custom.ini, for example:

[feature_toggles]
localeFormatPreference=true