POC: migrate provider helper

examples/migration.js

@@ -0,0 +1,27 @@
+const { initialize, migrateFlag } = require('../lib');
+
+const client = initialize({
+ appName: 'migration-application',
+ url: 'https://sandbox.getunleash.io/enterprise/api/',
+ refreshInterval: 3000,
+ metricsInterval: 3000,
+ environment: 'production',
+ customHeaders: {
+ Authorization: 'migration:development.924579bdb2542b96b8c00d3a22f2345c95b521e6b3717ad57ff8d43b',
+ },
+});
+client.on('error', console.error);
+client.on('warn', console.log);
+
+const homebrewFlagProvider = (_flag) => true || _flag; // mock
+
+setInterval(async () => {
+ const context = {
+ userId: `${Math.random() * 100}`,
+ sessionId: Math.round(Math.random() * 1000),
+ remoteAddress: '127.0.0.1',
+ };
+ const toggleName = 'initiative';
+ const value = await migrateFlag(toggleName, homebrewFlagProvider, context);
+ console.log(`${toggleName} enabled: ${value}`);
+}, 1000);

src/index.ts

@@ -81,3 +81,24 @@ export async function flushMetrics(): Promise<void> {
 export async function destroyWithFlush(): Promise<void> {
  return instance && instance.destroyWithFlush();
 }
+
+export async function migrateFlag(
+ flag: string,
+ evaluateLegacy: (flagName: string) => boolean | Promise<boolean>,
+ context?: Context,
+) {
+ const value = evaluateLegacy('flag');
+
+ if (!instance) return value;
+
+ if (
+ instance.isEnabled('isSafeMode') ||
+ !instance.isEnabled('isRolledOut', { flag, ...context })
+ ) {
+ (async () => instance.count(flag, await value))(); // only get metrics
+
+ return value;
+ }
+
+ return instance.isEnabled(flag);
+}