feat: add variant etag (#8922)

## About the changes
This adds a variant that allows us to control client refreshes in case
of need.

src/lib/features/client-feature-toggles/client-feature-toggle.controller.ts

@@ -285,8 +285,14 @@ export default class FeatureController extends Controller {
 
         // TODO: We will need to standardize this to be able to implement this a cross languages (Edge in Rust?).
         const queryHash = hashSum(query);
-        const etag = `"${queryHash}:${revisionId}"`;
-        return { revisionId, etag, queryHash };
+        const etagVariant = this.flagResolver.getVariant('etagVariant');
+        if (etagVariant.feature_enabled && etagVariant.enabled) {
+            const etag = `"${queryHash}:${revisionId}:${etagVariant.name}"`;
+            return { revisionId, etag, queryHash };
+        } else {
+            const etag = `"${queryHash}:${revisionId}"`;
+            return { revisionId, etag, queryHash };
+        }
     }
 
     async getFeatureToggle(

src/lib/features/client-feature-toggles/tests/client-feature-toggle.e2e.test.ts

@@ -54,6 +54,13 @@ beforeEach(async () => {
         isEnabled: () => {
             return false;
         },
+        getVariant: () => {
+            return {
+                name: 'disabled',
+                feature_enabled: false,
+                enabled: false,
+            };
+        },
     };
 });
 

src/lib/types/experimental.ts

@@ -60,7 +60,8 @@ export type IFlagKey =
     | 'deleteStaleUserSessions'
     | 'memorizeStats'
     | 'licensedUsers'
-    | 'streaming';
+    | 'streaming'
+    | 'etagVariant';
 
 export type IFlags = Partial<{ [key in IFlagKey]: boolean | Variant }>;
 
@@ -284,6 +285,11 @@ const flags: IFlags = {
         process.env.UNLEASH_EXPERIMENTAL_STREAMING,
         false,
     ),
+    etagVariant: {
+        name: 'disabled',
+        feature_enabled: false,
+        enabled: false,
+    },
 };
 
 export const defaultExperimentalOptions: IExperimentalOptions = {

src/test/e2e/api/client/feature.optimal304.e2e.test.ts

@@ -8,157 +8,204 @@ import type User from '../../../../lib/types/user';
 import { TEST_AUDIT_USER } from '../../../../lib/types';
 // import { DEFAULT_ENV } from '../../../../lib/util/constants';
 
-let app: IUnleashTest;
-let db: ITestDb;
 const testUser = { name: 'test', id: -9999 } as User;
 
-beforeAll(async () => {
-    db = await dbInit('feature_304_api_client', getLogger);
-    app = await setupAppWithCustomConfig(
-        db.stores,
-        {
-            experimental: {
-                flags: {
-                    strictSchemaValidation: true,
-                    optimal304: true,
+const shutdownHooks: (() => Promise<void>)[] = [];
+
+describe.each([
+    {
+        name: 'disabled',
+        enabled: false,
+        feature_enabled: false,
+    },
+    {
+        name: 'v2',
+        enabled: true,
+        feature_enabled: true,
+    },
+])('feature 304 api client (etag variant = %s)', (etagVariant) => {
+    let app: IUnleashTest;
+    let db: ITestDb;
+    const apendix = etagVariant.feature_enabled
+        ? `${etagVariant.name}`
+        : 'etag_variant_off';
+    beforeAll(async () => {
+        db = await dbInit(`feature_304_api_client_${apendix}`, getLogger);
+        app = await setupAppWithCustomConfig(
+            db.stores,
+            {
+                experimental: {
+                    flags: {
+                        strictSchemaValidation: true,
+                        etagVariant: etagVariant,
+                    },
                 },
             },
-        },
-        db.rawDatabase,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureX',
-            description: 'the #1 feature',
-            impressionData: true,
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureY',
-            description: 'soon to be the #1 feature',
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureZ',
-            description: 'terrible feature',
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureArchivedX',
-            description: 'the #1 feature',
-        },
-        TEST_AUDIT_USER,
-    );
+            db.rawDatabase,
+        );
 
-    await app.services.featureToggleService.archiveToggle(
-        'featureArchivedX',
-        testUser,
-        TEST_AUDIT_USER,
-    );
-
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureArchivedY',
-            description: 'soon to be the #1 feature',
-        },
-        TEST_AUDIT_USER,
-    );
-
-    await app.services.featureToggleService.archiveToggle(
-        'featureArchivedY',
-        testUser,
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureArchivedZ',
-            description: 'terrible feature',
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.archiveToggle(
-        'featureArchivedZ',
-        testUser,
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'feature.with.variants',
-            description: 'A feature flag with variants',
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.featureToggleService.saveVariants(
-        'feature.with.variants',
-        'default',
-        [
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
             {
-                name: 'control',
-                weight: 50,
-                weightType: 'fix',
-                stickiness: 'default',
+                name: `featureX${apendix}`,
+                description: 'the #1 feature',
+                impressionData: true,
             },
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
             {
-                name: 'new',
-                weight: 50,
-                weightType: 'variable',
-                stickiness: 'default',
+                name: `featureY${apendix}`,
+                description: 'soon to be the #1 feature',
             },
-        ],
-        TEST_AUDIT_USER,
-    );
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `featureZ${apendix}`,
+                description: 'terrible feature',
+            },
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `featureArchivedX${apendix}`,
+                description: 'the #1 feature',
+            },
+            TEST_AUDIT_USER,
+        );
+
+        await app.services.featureToggleService.archiveToggle(
+            `featureArchivedX${apendix}`,
+            testUser,
+            TEST_AUDIT_USER,
+        );
+
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `featureArchivedY${apendix}`,
+                description: 'soon to be the #1 feature',
+            },
+            TEST_AUDIT_USER,
+        );
+
+        await app.services.featureToggleService.archiveToggle(
+            `featureArchivedY${apendix}`,
+            testUser,
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `featureArchivedZ${apendix}`,
+                description: 'terrible feature',
+            },
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.archiveToggle(
+            `featureArchivedZ${apendix}`,
+            testUser,
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `feature.with.variants${apendix}`,
+                description: 'A feature flag with variants',
+            },
+            TEST_AUDIT_USER,
+        );
+        await app.services.featureToggleService.saveVariants(
+            `feature.with.variants${apendix}`,
+            'default',
+            [
+                {
+                    name: 'control',
+                    weight: 50,
+                    weightType: 'fix',
+                    stickiness: 'default',
+                },
+                {
+                    name: 'new',
+                    weight: 50,
+                    weightType: 'variable',
+                    stickiness: 'default',
+                },
+            ],
+            TEST_AUDIT_USER,
+        );
+
+        shutdownHooks.push(async () => {
+            await app.destroy();
+            await db.destroy();
+        });
+    });
+
+    test('returns calculated hash', async () => {
+        const res = await app.request
+            .get('/api/client/features')
+            .expect('Content-Type', /json/)
+            .expect(200);
+
+        if (etagVariant.feature_enabled) {
+            expect(res.headers.etag).toBe(`"61824cd0:17:${etagVariant.name}"`);
+            expect(res.body.meta.etag).toBe(
+                `"61824cd0:17:${etagVariant.name}"`,
+            );
+        } else {
+            expect(res.headers.etag).toBe('"61824cd0:16"');
+            expect(res.body.meta.etag).toBe('"61824cd0:16"');
+        }
+    });
+
+    test(`returns ${etagVariant.feature_enabled ? 200 : 304} for pre-calculated hash${etagVariant.feature_enabled ? ' because hash changed' : ''}`, async () => {
+        const res = await app.request
+            .get('/api/client/features')
+            .set('if-none-match', '"61824cd0:16"')
+            .expect(etagVariant.feature_enabled ? 200 : 304);
+
+        if (etagVariant.feature_enabled) {
+            expect(res.headers.etag).toBe(`"61824cd0:17:${etagVariant.name}"`);
+            expect(res.body.meta.etag).toBe(
+                `"61824cd0:17:${etagVariant.name}"`,
+            );
+        }
+    });
+
+    test('returns 200 when content updates and hash does not match anymore', async () => {
+        await app.services.featureToggleService.createFeatureToggle(
+            'default',
+            {
+                name: `featureNew304${apendix}`,
+                description: 'the #1 feature',
+            },
+            TEST_AUDIT_USER,
+        );
+        await app.services.configurationRevisionService.updateMaxRevisionId();
+
+        const res = await app.request
+            .get('/api/client/features')
+            .set('if-none-match', 'ae443048:16')
+            .expect(200);
+
+        if (etagVariant.feature_enabled) {
+            expect(res.headers.etag).toBe(`"61824cd0:17:${etagVariant.name}"`);
+            expect(res.body.meta.etag).toBe(
+                `"61824cd0:17:${etagVariant.name}"`,
+            );
+        } else {
+            expect(res.headers.etag).toBe('"61824cd0:17"');
+            expect(res.body.meta.etag).toBe('"61824cd0:17"');
+        }
+    });
 });
 
+// running after all inside describe block, causes some of the queries to fail to acquire a connection
+// this workaround is to run the afterAll outside the describe block
 afterAll(async () => {
-    await app.destroy();
-    await db.destroy();
-});
-
-test('returns calculated hash', async () => {
-    const res = await app.request
-        .get('/api/client/features')
-        .expect('Content-Type', /json/)
-        .expect(200);
-    expect(res.headers.etag).toBe('"61824cd0:16"');
-    expect(res.body.meta.etag).toBe('"61824cd0:16"');
-});
-
-test('returns 304 for pre-calculated hash', async () => {
-    return app.request
-        .get('/api/client/features')
-        .set('if-none-match', '"61824cd0:16"')
-        .expect(304);
-});
-
-test('returns 200 when content updates and hash does not match anymore', async () => {
-    await app.services.featureToggleService.createFeatureToggle(
-        'default',
-        {
-            name: 'featureNew304',
-            description: 'the #1 feature',
-        },
-        TEST_AUDIT_USER,
-    );
-    await app.services.configurationRevisionService.updateMaxRevisionId();
-
-    const res = await app.request
-        .get('/api/client/features')
-        .set('if-none-match', 'ae443048:16')
-        .expect(200);
-
-    expect(res.headers.etag).toBe('"61824cd0:17"');
-    expect(res.body.meta.etag).toBe('"61824cd0:17"');
+    await Promise.all(shutdownHooks.map((hook) => hook()));
 });