feat: add kill switch for client metrics (#4829)

This PR adds a killswitch for client metrics that we can use to disable
metrics in our cloud offering.

src/lib/__snapshots__/create-config.test.ts.snap

@@ -79,6 +79,7 @@ exports[`should create default config 1`] = `
       "demo": false,
       "dependentFeatures": false,
       "disableBulkToggle": false,
+      "disableMetrics": false,
       "disableNotifications": false,
       "doraMetrics": false,
       "embedProxy": true,
@@ -117,6 +118,7 @@ exports[`should create default config 1`] = `
       "demo": false,
       "dependentFeatures": false,
       "disableBulkToggle": false,
+      "disableMetrics": false,
       "disableNotifications": false,
       "doraMetrics": false,
       "embedProxy": true,

src/lib/routes/client-api/metrics.test.ts

@@ -254,3 +254,32 @@ test('should return a 200 if required fields are there', async () => {
         })
         .expect(202);
 });
+
+test('should return 204 if metrics are disabled by feature flag', async () => {
+    const { request: localRequest } = await getSetup({
+        experimental: {
+            flags: {
+                disableMetrics: true,
+            },
+        },
+    });
+
+    await localRequest
+        .post('/api/client/metrics')
+        .send({
+            appName: 'demo',
+            someParam: 'some-value',
+            somOtherParam: 'some--other-value',
+            bucket: {
+                start: Date.now(),
+                stop: Date.now(),
+                toggles: {
+                    toggleLastSeen: {
+                        yes: 200,
+                        no: 0,
+                    },
+                },
+            },
+        })
+        .expect(204);
+});

src/lib/routes/client-api/metrics.ts

@@ -58,6 +58,7 @@ export default class ClientMetricsController extends Controller {
                     responses: {
                         ...getStandardResponses(400),
                         202: emptyResponse,
+                        204: emptyResponse,
                     },
                 }),
             ],
@@ -65,13 +66,19 @@ export default class ClientMetricsController extends Controller {
     }
 
     async registerMetrics(req: IAuthRequest, res: Response): Promise<void> {
+        if (this.config.flagResolver.isEnabled('disableMetrics')) {
+            res.status(204).end();
+        } else {
             try {
                 const { body: data, ip: clientIp, user } = req;
                 data.environment = this.metricsV2.resolveMetricsEnvironment(
                     user,
                     data,
                 );
-            await this.clientInstanceService.registerInstance(data, clientIp);
+                await this.clientInstanceService.registerInstance(
+                    data,
+                    clientIp,
+                );
 
                 await this.metricsV2.registerClientMetrics(data, clientIp);
                 res.status(202).end();
@@ -79,4 +86,5 @@ export default class ClientMetricsController extends Controller {
                 res.status(400).end();
             }
         }
+    }
 }

src/lib/routes/proxy-api/index.ts

@@ -108,6 +108,7 @@ export default class ProxyController extends Controller {
                     requestBody: createRequestSchema('clientMetricsSchema'),
                     responses: {
                         200: emptyResponse,
+                        204: emptyResponse,
                         ...getStandardResponses(400, 401, 404),
                     },
                 }),
@@ -189,6 +190,12 @@ export default class ProxyController extends Controller {
         if (!this.config.flagResolver.isEnabled('embedProxy')) {
             throw new NotFoundError();
         }
+
+        if (this.config.flagResolver.isEnabled('disableMetrics')) {
+            res.sendStatus(204);
+            return;
+        }
+
         await this.services.proxyService.registerProxyMetrics(
             req.user,
             req.body,

src/lib/types/experimental.ts

@@ -30,7 +30,8 @@ export type IFlagKey =
     | 'accessOverview'
     | 'privateProjects'
     | 'dependentFeatures'
-    | 'datadogJsonTemplate';
+    | 'datadogJsonTemplate'
+    | 'disableMetrics';
 
 export type IFlags = Partial<{ [key in IFlagKey]: boolean | Variant }>;
 
@@ -142,6 +143,10 @@ const flags: IFlags = {
         process.env.UNLEASH_EXPERIMENTAL_DATADOG_JSON_TEMPLATE,
         false,
     ),
+    disableMetrics: parseEnvVarBoolean(
+        process.env.UNLEASH_EXPERIMENTAL_DISABLE_METRICS,
+        false,
+    ),
 };
 
 export const defaultExperimentalOptions: IExperimentalOptions = {

src/test/e2e/api/proxy/proxy.e2e.test.ts

@@ -1193,3 +1193,42 @@ test('should NOT evaluate disabled strategies when returning toggles', async ()
             });
         });
 });
+
+test('should return 204 if metrics are disabled', async () => {
+    const localApp = await setupAppWithAuth(db.stores, {
+        frontendApiOrigins: ['https://example.com'],
+        experimental: {
+            flags: {
+                disableMetrics: true,
+            },
+        },
+    });
+
+    const frontendToken =
+        await localApp.services.apiTokenService.createApiTokenWithProjects({
+            type: ApiTokenType.FRONTEND,
+            projects: ['*'],
+            environment: 'default',
+            tokenName: `disabledMetric-token-${randomId()}`,
+        });
+
+    const appName = randomId();
+    const instanceId = randomId();
+    const featureName = 'metricsDisabled';
+
+    const now = new Date();
+
+    await localApp.request
+        .post('/api/frontend/client/metrics')
+        .set('Authorization', frontendToken.secret)
+        .send({
+            appName,
+            instanceId,
+            bucket: {
+                start: now,
+                stop: now,
+                toggles: { [featureName]: { yes: 2, no: 20 } },
+            },
+        })
+        .expect(204);
+});