feat: Utility class to produce IConfigurationWire instances (#241)

* chore: gather configuration-wire code
* lint
* feat: Configuration Helper to fetch and encode config
* feat: export config helper

Author: typotter

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk-common",
-  "version": "4.13.5",
+  "version": "4.14.0",
   "description": "Common library for Eppo JavaScript SDKs (web, react native, and node)",
   "main": "dist/index.js",
   "files": [

src/client/eppo-client-with-bandits.spec.ts

@@ -18,7 +18,7 @@ import {
   IConfigurationWire,
   IPrecomputedConfiguration,
   IObfuscatedPrecomputedConfigurationResponse,
-} from '../configuration-wire-types';
+} from '../configuration-wire/configuration-wire-types';
 import { Evaluator, FlagEvaluation } from '../evaluator';
 import {
   AllocationEvaluationCode,

src/client/eppo-client.spec.ts

@@ -21,7 +21,7 @@ import {
   IConfigurationWire,
   IObfuscatedPrecomputedConfigurationResponse,
   ObfuscatedPrecomputedConfigurationResponse,
-} from '../configuration-wire-types';
+} from '../configuration-wire/configuration-wire-types';
 import { MAX_EVENT_QUEUE_SIZE, DEFAULT_POLL_INTERVAL_MS, POLL_JITTER_PCT } from '../constants';
 import { decodePrecomputedFlag } from '../decoding';
 import { Flag, ObfuscatedFlag, VariationType, FormatEnum, Variation } from '../interfaces';

src/client/eppo-client.ts

@@ -22,7 +22,7 @@ import {
   IConfigurationWire,
   IPrecomputedConfiguration,
   PrecomputedConfiguration,
-} from '../configuration-wire-types';
+} from '../configuration-wire/configuration-wire-types';
 import {
   DEFAULT_INITIAL_CONFIG_REQUEST_RETRIES,
   DEFAULT_POLL_CONFIG_REQUEST_RETRIES,

src/client/eppo-precomputed-client.spec.ts

@@ -13,7 +13,7 @@ import {
 } from '../attributes';
 import { IConfigurationStore, ISyncStore } from '../configuration-store/configuration-store';
 import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
-import { IPrecomputedConfigurationResponse } from '../configuration-wire-types';
+import { IPrecomputedConfigurationResponse } from '../configuration-wire/configuration-wire-types';
 import { DEFAULT_POLL_INTERVAL_MS, MAX_EVENT_QUEUE_SIZE, POLL_JITTER_PCT } from '../constants';
 import FetchHttpClient from '../http-client';
 import {

src/configuration-wire/configuration-wire-helper.spec.ts

@@ -0,0 +1,98 @@
+import { IBanditParametersResponse, IUniversalFlagConfigResponse } from '../http-client';
+import { FormatEnum } from '../interfaces';
+import { getMD5Hash } from '../obfuscation';
+
+import { ConfigurationWireHelper } from './configuration-wire-helper';
+
+const TEST_BASE_URL = 'https://us-central1-eppo-qa.cloudfunctions.net/serveGitHubRacTestFile';
+const DUMMY_SDK_KEY = 'dummy-sdk-key';
+
+// This SDK causes the cloud endpoint below to serve the UFC test file with bandit flags.
+const BANDIT_SDK_KEY = 'this-key-serves-bandits';
+
+describe('ConfigurationWireHelper', () => {
+  describe('getBootstrapConfigurationFromApi', () => {
+    it('should fetch obfuscated flags with android SDK', async () => {
+      const helper = ConfigurationWireHelper.build(DUMMY_SDK_KEY, {
+        sdkName: 'android',
+        sdkVersion: '4.0.0',
+        baseUrl: TEST_BASE_URL,
+      });
+
+      const wirePacket = await helper.fetchBootstrapConfiguration();
+
+      expect(wirePacket.version).toBe(1);
+      expect(wirePacket.config).toBeDefined();
+
+      if (!wirePacket.config) {
+        throw new Error('Flag config not present in ConfigurationWire');
+      }
+
+      const configResponse = JSON.parse(wirePacket.config.response) as IUniversalFlagConfigResponse;
+      expect(configResponse.format).toBe(FormatEnum.CLIENT);
+      expect(configResponse.flags).toBeDefined();
+      expect(Object.keys(configResponse.flags).length).toBeGreaterThan(1);
+      expect(Object.keys(configResponse.flags)).toHaveLength(19);
+
+      const testFlagKey = getMD5Hash('numeric_flag');
+      expect(Object.keys(configResponse.flags)).toContain(testFlagKey);
+
+      // No bandits.
+      expect(configResponse.banditReferences).toBeUndefined();
+      expect(wirePacket.bandits).toBeUndefined();
+    });
+
+    it('should fetch flags and bandits for node-server SDK', async () => {
+      const helper = ConfigurationWireHelper.build(BANDIT_SDK_KEY, {
+        sdkName: 'node-server',
+        sdkVersion: '4.0.0',
+        baseUrl: TEST_BASE_URL,
+      });
+
+      const wirePacket = await helper.fetchBootstrapConfiguration();
+
+      expect(wirePacket.version).toBe(1);
+      expect(wirePacket.config).toBeDefined();
+
+      if (!wirePacket.config) {
+        throw new Error('Flag config not present in ConfigurationWire');
+      }
+
+      const configResponse = JSON.parse(wirePacket.config.response) as IUniversalFlagConfigResponse;
+      expect(configResponse.format).toBe(FormatEnum.SERVER);
+      expect(configResponse.flags).toBeDefined();
+      expect(configResponse.banditReferences).toBeDefined();
+      expect(Object.keys(configResponse.flags)).toContain('banner_bandit_flag');
+      expect(Object.keys(configResponse.flags)).toContain('car_bandit_flag');
+
+      expect(wirePacket.bandits).toBeDefined();
+      const banditResponse = JSON.parse(
+        wirePacket.bandits?.response ?? '',
+      ) as IBanditParametersResponse;
+      expect(Object.keys(banditResponse.bandits).length).toBeGreaterThan(1);
+      expect(Object.keys(banditResponse.bandits)).toContain('banner_bandit');
+      expect(Object.keys(banditResponse.bandits)).toContain('car_bandit');
+    });
+
+    it('should include fetchedAt timestamps', async () => {
+      const helper = ConfigurationWireHelper.build(BANDIT_SDK_KEY, {
+        sdkName: 'android',
+        sdkVersion: '4.0.0',
+        baseUrl: TEST_BASE_URL,
+      });
+
+      const wirePacket = await helper.fetchBootstrapConfiguration();
+
+      if (!wirePacket.config) {
+        throw new Error('Flag config not present in ConfigurationWire');
+      }
+      if (!wirePacket.bandits) {
+        throw new Error('Bandit config not present in ConfigurationWire');
+      }
+
+      expect(wirePacket.config.fetchedAt).toBeDefined();
+      expect(Date.parse(wirePacket.config.fetchedAt ?? '')).not.toBeNaN();
+      expect(Date.parse(wirePacket.bandits.fetchedAt ?? '')).not.toBeNaN();
+    });
+  });
+});

src/configuration-wire/configuration-wire-helper.ts

@@ -0,0 +1,75 @@
+import ApiEndpoints from '../api-endpoints';
+import FetchHttpClient, {
+  IBanditParametersResponse,
+  IHttpClient,
+  IUniversalFlagConfigResponse,
+} from '../http-client';
+
+import { ConfigurationWireV1, IConfigurationWire } from './configuration-wire-types';
+
+export type SdkOptions = {
+  sdkName: string;
+  sdkVersion: string;
+  baseUrl?: string;
+};
+
+/**
+ * Helper class for fetching and converting configuration from the Eppo API(s).
+ */
+export class ConfigurationWireHelper {
+  private httpClient: IHttpClient;
+
+  /**
+   * Build a new ConfigurationHelper for the target SDK Key.
+   * @param sdkKey
+   */
+  public static build(
+    sdkKey: string,
+    opts: SdkOptions = { sdkName: 'android', sdkVersion: '4.0.0' },
+  ) {
+    const { sdkName, sdkVersion, baseUrl } = opts;
+    return new ConfigurationWireHelper(sdkKey, sdkName, sdkVersion, baseUrl);
+  }
+
+  private constructor(
+    sdkKey: string,
+    targetSdkName = 'android',
+    targetSdkVersion = '4.0.0',
+    baseUrl?: string,
+  ) {
+    const queryParams = {
+      sdkName: targetSdkName,
+      sdkVersion: targetSdkVersion,
+      apiKey: sdkKey,
+    };
+    const apiEndpoints = new ApiEndpoints({
+      baseUrl,
+      queryParams,
+    });
+
+    this.httpClient = new FetchHttpClient(apiEndpoints, 5000);
+  }
+
+  /**
+   * Fetches configuration data from the API and build a Bootstrap Configuration (aka an `IConfigurationWire` object).
+   * The IConfigurationWire instance can be used to bootstrap some SDKs.
+   */
+  public async fetchBootstrapConfiguration(): Promise<IConfigurationWire> {
+    // Get the configs
+    let banditResponse: IBanditParametersResponse | undefined;
+    const configResponse: IUniversalFlagConfigResponse | undefined =
+      await this.httpClient.getUniversalFlagConfiguration();
+
+    if (!configResponse?.flags) {
+      console.warn('Unable to fetch configuration, returning empty configuration');
+      return Promise.resolve(ConfigurationWireV1.empty());
+    }
+
+    const flagsHaveBandits = Object.keys(configResponse.banditReferences ?? {}).length > 0;
+    if (flagsHaveBandits) {
+      banditResponse = await this.httpClient.getBanditParameters();
+    }
+
+    return ConfigurationWireV1.fromResponses(configResponse, banditResponse);
+  }
+}

src/configuration-wire-types.spec.ts renamed to src/configuration-wire/configuration-wire-types.spec.ts

@@ -2,11 +2,11 @@ import {
   MOCK_BANDIT_MODELS_RESPONSE_FILE,
   MOCK_FLAGS_WITH_BANDITS_RESPONSE_FILE,
   readMockUFCResponse,
-} from '../test/testHelpers';
+} from '../../test/testHelpers';
+import { IUniversalFlagConfigResponse, IBanditParametersResponse } from '../http-client';
+import { FormatEnum } from '../interfaces';
 
 import { ConfigurationWireV1, deflateResponse, inflateResponse } from './configuration-wire-types';
-import { IUniversalFlagConfigResponse, IBanditParametersResponse } from './http-client';
-import { FormatEnum } from './interfaces';
 
 describe('Response String Type Safety', () => {
   const mockFlagConfig: IUniversalFlagConfigResponse = readMockUFCResponse(

src/configuration-wire-types.ts renamed to src/configuration-wire/configuration-wire-types.ts

@@ -1,13 +1,13 @@
-import { IUniversalFlagConfigResponse, IBanditParametersResponse } from './http-client';
+import { IUniversalFlagConfigResponse, IBanditParametersResponse } from '../http-client';
 import {
   Environment,
   FormatEnum,
   IObfuscatedPrecomputedBandit,
   IPrecomputedBandit,
   PrecomputedFlag,
-} from './interfaces';
-import { obfuscatePrecomputedBanditMap, obfuscatePrecomputedFlags } from './obfuscation';
-import { ContextAttributes, FlagKey, HashedFlagKey } from './types';
+} from '../interfaces';
+import { obfuscatePrecomputedBanditMap, obfuscatePrecomputedFlags } from '../obfuscation';
+import { ContextAttributes, FlagKey, HashedFlagKey } from '../types';
 
 // Base interface for all configuration responses
 interface IBasePrecomputedConfigurationResponse {

src/http-client.ts

@@ -1,5 +1,5 @@
 import ApiEndpoints from './api-endpoints';
-import { IObfuscatedPrecomputedConfigurationResponse } from './configuration-wire-types';
+import { IObfuscatedPrecomputedConfigurationResponse } from './configuration-wire/configuration-wire-types';
 import {
   BanditParameters,
   BanditReference,