fix: memoize config CDN call (#1000)

Author: ajwootto

sdk/nextjs/src/server/bucketing.ts

@@ -6,7 +6,7 @@ import {
     BucketedConfigWithAdditionalFields,
     DevCycleNextOptions,
 } from '../common/types'
-import { BucketedUserConfig, ConfigBody, ConfigSource } from '@devcycle/types'
+import { ConfigBody, ConfigSource } from '@devcycle/types'
 
 const getPopulatedUser = cache((user: DevCycleUser, userAgent?: string) => {
     return new DVCPopulatedUser(
@@ -67,18 +67,14 @@ class CDNConfigSource extends ConfigSource {
     }
     async getConfig(sdkKey: string, kind: string, obfuscated: boolean) {
         // this request will be cached by Next
-        const cdnConfig = await fetchCDNConfig(
+        const { config, headers } = await fetchCDNConfig(
             sdkKey,
             this.clientSDKKey,
             obfuscated,
         )
-        if (!cdnConfig.ok) {
-            const responseText = await cdnConfig.text()
-            throw new Error('Could not fetch config: ' + responseText)
-        }
         return {
-            config: (await cdnConfig.json()) as ConfigBody,
-            lastModified: cdnConfig.headers.get('last-modified'),
+            config: config,
+            lastModified: headers.get('last-modified'),
             metaData: {},
         }
     }

sdk/nextjs/src/server/requests.ts

@@ -1,29 +1,40 @@
 import { DVCPopulatedUser } from '@devcycle/js-client-sdk'
 import { serializeUserSearchParams } from '../common/serializeUser'
 import { cache } from 'react'
-import { BucketedUserConfig } from '@devcycle/types'
+import { BucketedUserConfig, ConfigBody } from '@devcycle/types'
 
 const getFetchUrl = (sdkKey: string, obfuscated: boolean) =>
     `https://config-cdn.devcycle.com/config/v2/server/bootstrap/${
         obfuscated ? 'obfuscated/' : ''
     }${sdkKey}.json`
 
-export const fetchCDNConfig = async (
-    sdkKey: string,
-    clientSDKKey: string,
-    obfuscated: boolean,
-): Promise<Response> => {
-    return await fetch(
-        getFetchUrl(sdkKey, obfuscated),
-        // only store for 60 seconds
-        {
-            next: {
-                revalidate: 60,
-                tags: [sdkKey, clientSDKKey],
+export const fetchCDNConfig = cache(
+    async (
+        sdkKey: string,
+        clientSDKKey: string,
+        obfuscated: boolean,
+    ): Promise<{ config: ConfigBody; headers: Headers }> => {
+        const response = await fetch(
+            getFetchUrl(sdkKey, obfuscated),
+            // only store for 60 seconds
+            {
+                next: {
+                    revalidate: 60,
+                    tags: [sdkKey, clientSDKKey],
+                },
             },
-        },
-    )
-}
+        )
+
+        if (!response.ok) {
+            const responseText = await response.text()
+            throw new Error('Could not fetch config: ' + responseText)
+        }
+        return {
+            config: (await response.json()) as ConfigBody,
+            headers: response.headers,
+        }
+    },
+)
 
 const getSDKAPIUrl = (
     sdkKey: string,