fix statsig usage (#911)

Prevent statsig from fetching in middleware.

- Turning on `localMode` will log an error on any network activity
- Setting `initStrategyForIDLists: "never"` will prevent Statsig from
attempting to fetch the ID List over the network, as ID Lists are not
supported by the Edge Config Adapter (yet)

edge-middleware/ab-testing-statsig/middleware.ts

@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse, NextFetchEvent } from 'next/server'
-import Statsig from 'statsig-node'
+import Statsig from 'statsig-node-lite'
 import { EdgeConfigDataAdapter } from 'statsig-node-vercel'
 import { createClient } from '@vercel/edge-config'
 import { EXPERIMENT, UID_COOKIE, GROUP_PARAM_FALLBACK } from './lib/constants'
@@ -28,9 +28,32 @@ export async function middleware(req: NextRequest, event: NextFetchEvent) {
     hasUserId = false
   }
 
-  await Statsig.initialize(process.env.STATSIG_SERVER_API_KEY!, { dataAdapter })
+  await Statsig.initialize(process.env.STATSIG_SERVER_API_KEY!, {
+    // 🚨 It's extremly important to set this, otherwise Statsig will attempt
+    // to fetch the ID List over the network, which is slow and would render
+    // using the Edge Config Adapter useless.
+    //
+    // If you are not using the ID List feature, set this to "none".
+    //
+    // Otherwise consider setting it to "lazy" but be aware of the consequences
+    // that the ID List will not apply in most cases as it will only get fetched
+    // after the experiment ran
+    initStrategyForIDLists: 'none',
+    // 🚨 This setting will prevent Statsig from making any network requests,
+    // thus ensuring middleware stays extremly fast.
+    localMode: true,
+    // This makes Statsig load experiments from Edge Config
+    dataAdapter,
+    // Disable any syncing to prevent network activity, as Edge Config will
+    // return the latest values anyhow, and as ID Lists are disabled.
+    disableIdListsSync: true,
+    disableRulesetsSync: true,
+  })
 
-  const experiment = await Statsig.getExperiment({ userID: userId }, EXPERIMENT)
+  const experiment = Statsig.getExperimentWithExposureLoggingDisabledSync(
+    { userID: userId },
+    EXPERIMENT
+  )
   const bucket = experiment.get<string>('bucket', GROUP_PARAM_FALLBACK)
 
   // Clone the URL and change its pathname to point to a bucket
@@ -48,7 +71,9 @@ export async function middleware(req: NextRequest, event: NextFetchEvent) {
   }
 
   // Flush exposure logs to Statsig
-  event.waitUntil(Statsig.flush())
+  // Disabled as we activated localMode. Turn localMode off if you need to log
+  // exposures from here.
+  // event.waitUntil(Statsig.flush())
 
   return res
 }

edge-middleware/ab-testing-statsig/package.json

@@ -15,8 +15,8 @@
     "next": "canary",
     "react": "latest",
     "react-dom": "latest",
-    "statsig-node": "^5.9.3",
-    "statsig-node-vercel": "^0.2.0",
+    "statsig-node-lite": "0.2.0",
+    "statsig-node-vercel": "0.2.0",
     "statsig-react": "^1.30.3"
   },
   "devDependencies": {