Add ability to use KV for persistent cache on workers

Author: brawaru

config/storages.ts

@@ -0,0 +1,92 @@
+import type { StorageMounts } from 'nitropack'
+
+// https://nuxt.com/docs/api/configuration/nuxt-config
+declare global {
+  namespace NodeJS {
+    interface ProcessEnv {
+      /** Preset used to build Nitro (provided manually). */
+      NITRO_PRESET?: string
+
+      /** Cloudflare KV via binding: name of the binding. */
+      CF_KV_BINDING_CACHE?: string
+
+      /** Vercel KV: token. */
+      KV_REST_API_TOKEN?: string
+      /** Vercel KV: API URL. */
+      KV_REST_API_URL?: string
+      /**
+       * Vercel KV: base name for cache KV.
+       * @default 'cache'
+       */
+      VERCEL_KV_CACHE_BASE?: string
+
+      /** Cache storage option. */
+      CACHE_STORAGE_OPTION?: string
+    }
+  }
+}
+
+/**
+ * Checks that all environment variables are defined.
+ * @param vars Variables to check.
+ * @returns All missing variables.
+ */
+function getMissingVars(vars: string[]) {
+  return vars.filter((varName) => !process.env[varName])
+}
+
+/**
+ * Returns Nitro storage mounts or nothing.
+ */
+function getCacheStorageMount(): StorageMounts[string] | undefined {
+  switch (process.env.CACHE_STORAGE_OPTION) {
+    case 'cloudflare-kv': {
+      if (process.env.CF_KV_BINDING_CACHE) {
+        return {
+          driver: '~/server/storage/cached-cloudflare-kv-binding',
+          binding: process.env.CF_KV_BINDING_CACHE,
+        }
+      }
+
+      console.warn(
+        'You wanted to use `cloudflare-kv` cache store option, however you have not provided `CF_KV_BINDING_CACHE` environment variable. The cache will use in-memory storage that is not persistent in workers.'
+      )
+
+      break
+    }
+    case 'vercel-kv': {
+      const missingVars = getMissingVars(['KV_REST_API_TOKEN', 'KV_REST_API_URL'])
+
+      if (!missingVars.length) {
+        return {
+          driver: '~/server/storage/cached-vercel-kv',
+          base: process.env.VERCEL_KV_CACHE_BASE || 'cache',
+          url: process.env.KV_REST_API_URL,
+          token: process.env.KV_REST_API_TOKEN,
+          env: false,
+        }
+      }
+
+      console.log(
+        `You wanted to use \`vercel-kv\` cache store option, however you have not provided ${missingVars
+          .map((varName) => `\`${varName}\``)
+          .join(
+            ', '
+          )} environment variable. The cache will use in-memory storage taht is not persistent in serverless functions.`
+      )
+
+      break
+    }
+  }
+
+  return undefined
+}
+
+export function getStorageMounts(): StorageMounts | undefined {
+  let mounts: StorageMounts | undefined
+
+  const cacheMount = getCacheStorageMount()
+  if (cacheMount != null) (mounts ??= {}).cache = cacheMount
+
+  return mounts
+}

nuxt.config.ts

@@ -5,6 +5,7 @@ import { resolve, basename } from 'pathe'
 import { defineNuxtConfig } from 'nuxt/config'
 import { globIterate } from 'glob'
 import { match as matchLocale } from '@formatjs/intl-localematcher'
+import { getStorageMounts } from './config/storages.ts'
 
 const STAGING_API_URL = 'https://staging-api.modrinth.com/v2/'
 
@@ -249,6 +250,7 @@ export default defineNuxtConfig({
     siteKey: '0x4AAAAAAAHWfmKCm7cUG869',
   },
   nitro: {
+    storage: getStorageMounts(),
     moduleSideEffects: ['@vintl/compact-number/locale-data'],
   },
   devtools: {

package.json

@@ -19,6 +19,7 @@
     "@types/node": "^20.1.0",
     "@typescript-eslint/eslint-plugin": "^5.59.8",
     "@typescript-eslint/parser": "^5.59.8",
+    "@vercel/kv": "^0.2.2",
     "@vintl/compact-number": "^2.0.4",
     "@vintl/how-ago": "^2.0.1",
     "@vintl/nuxt": "^1.3.0",

pnpm-lock.yaml

@@ -0,0 +1,7 @@
+import cloudflareKVStorage, { KVOptions } from 'unstorage/drivers/cloudflare-kv-binding'
+import { Driver } from 'unstorage'
+import cachedDriver from './cached.ts'
+
+export default function cachedVercelKV(opts: KVOptions): Driver {
+  return cachedDriver({ driver: cloudflareKVStorage(opts) })
+}

server/storage/cached-cloudflare-kv-binding.ts

@@ -0,0 +1,7 @@
+import vercelStorage, { VercelKVOptions } from 'unstorage/drivers/vercel-kv'
+import { Driver } from 'unstorage'
+import cachedDriver from './cached.ts'
+
+export default function cachedVercelKV(opts: VercelKVOptions): Driver {
+  return cachedDriver({ driver: vercelStorage(opts) })
+}

server/storage/cached-vercel-kv.ts

@@ -0,0 +1,31 @@
+import { Driver } from 'unstorage'
+import memoryDriver from 'unstorage/drivers/memory'
+
+export interface CachedOptions {
+  driver: Driver
+}
+
+export default function cached(options: CachedOptions): Driver {
+  const { driver } = options
+  const memory = memoryDriver() as Driver
+  return {
+    ...driver,
+    name: driver.name ? `cached:${driver.name}` : `cached`,
+    options,
+    async hasItem(key) {
+      return (await memory.hasItem(key, {})) || (await driver.hasItem(key, {}))
+    },
+    async getItem(key) {
+      const memoryLookup = await memory.getItem(key)
+      if (memoryLookup !== null) return memoryLookup
+
+      const lookup = await driver.getItem(key)
+      memory.setItem!(key, lookup as any, {})
+      return lookup
+    },
+    async setItem(key, value) {
+      memory.setItem!(key, value, {})
+      await driver.setItem?.(key, value, {})
+    },
+  }
+}