fix: add shutdown to flagd-web provider (#325)

Signed-off-by: Todd Baert <toddbaert@gmail.com>

Author: toddbaert

libs/providers/flagd-web/src/lib/flagd-web-provider.spec.ts

@@ -1,4 +1,4 @@
-import { CallbackClient, Code, ConnectError, PromiseClient } from '@bufbuild/connect-web';
+import { CallbackClient, Code, ConnectError, PromiseClient } from '@bufbuild/connect';
 import { Struct } from '@bufbuild/protobuf';
 import { Client, ErrorCode, JsonValue, OpenFeature, ProviderEvents, StandardResolutionReasons } from '@openfeature/web-sdk';
 import fetchMock from 'jest-fetch-mock';
@@ -35,14 +35,19 @@ class MockCallbackClient implements Partial<CallbackClient<typeof Service>> {
  */
  fail = false;
 
+ // use to fire an incoming mock message
  mockMessage(message: Partial<EventStreamResponse>) {
  this.messageCallback?.(message as EventStreamResponse);
  }
 
+ // use to fire a mock connection close
  mockClose(error: Partial<ConnectError>) {
  this.closeCallback?.(error as ConnectError);
  }
 
+ // cancel function stub to make assertions against
+ cancelFunction = jest.fn(() => undefined);
+
  eventStream = jest.fn(
  (
  _,
@@ -57,7 +62,7 @@ class MockCallbackClient implements Partial<CallbackClient<typeof Service>> {
  setTimeout(() => this.closeCallback?.({ code: Code.Unavailable } as unknown as ConnectError), 0);
  }
 
- return () => undefined;
+ return this.cancelFunction;
  }
  );
 }
@@ -239,6 +244,34 @@ describe(FlagdWebProvider.name, () => {
  });
  });
 
+ describe('shutdown', () => {
+ let client: Client;
+ let mockCallbackClient: MockCallbackClient;
+ const mockPromiseClient = new MockPromiseClient() as unknown as PromiseClient<typeof Service>;
+ const context = { some: 'value' };
+
+ beforeEach(() => {
+ mockCallbackClient = new MockCallbackClient();
+ OpenFeature.setProvider(
+ new FlagdWebProvider(
+ { host: 'fake.com', maxRetries: -1 },
+ console,
+ mockPromiseClient,
+ mockCallbackClient as unknown as CallbackClient<typeof Service>
+ )
+ );
+ client = OpenFeature.getClient('events-test');
+ });
+
+ describe('API close', () => {
+ it('should call cancel function on provider', () => {
+ expect(mockCallbackClient.cancelFunction).not.toHaveBeenCalled();
+ OpenFeature.close();
+ expect(mockCallbackClient.cancelFunction).toHaveBeenCalled();
+ });
+ });
+ });
+
  describe('reconnect logic', () => {
  describe('Infinite maxRetries', () => {
  it('should attempt reconnect many times', (done) => {

libs/providers/flagd-web/src/lib/flagd-web-provider.ts

@@ -1,10 +1,5 @@
-import {
- CallbackClient,
- createCallbackClient,
- createConnectTransport,
- createPromiseClient,
- PromiseClient,
-} from '@bufbuild/connect-web';
+import { CallbackClient, createCallbackClient, createPromiseClient, PromiseClient } from '@bufbuild/connect';
+import { createConnectTransport } from '@bufbuild/connect-web';
 import { Struct } from '@bufbuild/protobuf';
 import {
  EvaluationContext,
@@ -47,6 +42,7 @@ export class FlagdWebProvider implements Provider {
  private _delayMs = INITIAL_DELAY_MS;
  private _logger?: Logger;
  private _flags: { [key: string]: ResolutionDetails<FlagValue> & { type: AnyFlagResolutionType } } = {};
+ private _cancelFunction: (() => void) | undefined;
 
  constructor(
  options: FlagdProviderOptions,
@@ -91,6 +87,11 @@ export class FlagdWebProvider implements Provider {
  return this.evaluate(flagKey, 'objectValue');
  }
 
+ onClose(): Promise<void> {
+ // close the stream using the saved cancel function
+ return Promise.resolve(this._cancelFunction?.());
+ }
+
  private evaluate<T extends FlagValue>(flagKey: string, type: AnyFlagResolutionType): ResolutionDetails<T> {
  const resolved = this._flags[flagKey];
  if (!resolved) {
@@ -100,6 +101,7 @@ export class FlagdWebProvider implements Provider {
  throw new TypeMismatchError(`flag key ${flagKey} is not of type ${type}`);
  }
  return {
+ // return reason=CACHED if we're disconnected since we can't guarantee things are up to date
  reason: this._connected ? resolved.reason : StandardResolutionReasons.CACHED,
  variant: resolved.variant,
  value: resolved.value as T,
@@ -110,7 +112,7 @@ export class FlagdWebProvider implements Provider {
  this._delayMs = Math.min(this._delayMs * BACK_OFF_MULTIPLIER, this._maxDelay);
 
  return new Promise<void>((resolve) => {
- this._callbackClient.eventStream(
+ this._cancelFunction = this._callbackClient.eventStream(
  {},
  (message) => {
  // get the context at the time of the message
@@ -131,8 +133,9 @@ export class FlagdWebProvider implements Provider {
  }
  }
  },
- () => {
- this._logger?.error(`${FlagdWebProvider.name}: could not establish connection to flagd`);
+ (err) => {
+ this._logger?.error(`${FlagdWebProvider.name}: could not establish connection to flagd, ${err?.message}`);
+ this._logger?.debug(err?.stack);
  if (this._retry < this._maxRetries) {
  this._retry++;
  setTimeout(() => this.retryConnect(), this._delayMs);