This patch allow using redis or keyDB for caching next.js's image optimizer cache, for yarn on next 15.1.2

next-npm-15.1.2-24e7411703.patch

diff --git a/dist/server/image-optimizer.js b/dist/server/image-optimizer.js
index bf6beaeeffab903e0b02677fd633729df20f27ed..ce0549fbd0b21d7f4c610958e9eb1bcd0b5d79f8 100644
--- a/dist/server/image-optimizer.js
+++ b/dist/server/image-optimizer.js
@@ -466,33 +466,57 @@ class ImageOptimizerCache {
             mimeType
         ]);
     }
-    constructor({ distDir, nextConfig }){
+    constructor({ distDir, nextConfig, redisClient }){
         this.cacheDir = (0, _path.join)(distDir, 'cache', 'images');
         this.nextConfig = nextConfig;
+        this.redisClient = redisClient;
     }
     async get(cacheKey) {
         try {
-            const cacheDir = (0, _path.join)(this.cacheDir, cacheKey);
-            const files = await _fs.promises.readdir(cacheDir);
-            const now = Date.now();
-            for (const file of files){
-                const [maxAgeSt, expireAtSt, etag, upstreamEtag, extension] = file.split('.', 5);
-                const buffer = await _fs.promises.readFile((0, _path.join)(cacheDir, file));
+            if (process.env.REDIS_IMAGE_CACHE === 'true') {
+                const file = await this.redisClient.hgetall(cacheKey)
+                if (Object.keys(file).length === 0) return null
+                
+                const now = Date.now();
+                const {maxAge: maxAgeSt, expireAt: expireAtSt, etag, upstreamEtag, extension, buffer} = file;
                 const expireAt = Number(expireAtSt);
                 const maxAge = Number(maxAgeSt);
                 return {
                     value: {
                         kind: _responsecache.CachedRouteKind.IMAGE,
-                        etag,
-                        buffer,
-                        extension,
-                        upstreamEtag
+                    etag,
+                    buffer: Buffer.from(buffer, "base64"),
+                    extension,
+                    upstreamEtag
                     },
                     revalidateAfter: Math.max(maxAge, this.nextConfig.images.minimumCacheTTL) * 1000 + Date.now(),
                     curRevalidate: maxAge,
                     isStale: now > expireAt,
                     isFallback: false
                 };
+            } else {
+                const cacheDir = (0, _path.join)(this.cacheDir, cacheKey);
+                const files = await _fs.promises.readdir(cacheDir);
+                const now = Date.now();
+                for (const file of files){
+                    const [maxAgeSt, expireAtSt, etag, upstreamEtag, extension] = file.split('.', 5);
+                    const buffer = await _fs.promises.readFile((0, _path.join)(cacheDir, file));
+                    const expireAt = Number(expireAtSt);
+                    const maxAge = Number(maxAgeSt);
+                    return {
+                        value: {
+                            kind: _responsecache.CachedRouteKind.IMAGE,
+                            etag,
+                            buffer,
+                            extension,
+                            upstreamEtag
+                        },
+                        revalidateAfter: Math.max(maxAge, this.nextConfig.images.minimumCacheTTL) * 1000 + Date.now(),
+                        curRevalidate: maxAge,
+                        isStale: now > expireAt,
+                        isFallback: false
+                    };
+                }
             }
         } catch (_) {
         // failed to read from cache dir, treat as cache miss
@@ -508,7 +532,18 @@ class ImageOptimizerCache {
         }
         const expireAt = Math.max(revalidate, this.nextConfig.images.minimumCacheTTL) * 1000 + Date.now();
         try {
-            await writeToCacheDir((0, _path.join)(this.cacheDir, cacheKey), value.extension, revalidate, expireAt, value.buffer, value.etag, value.upstreamEtag);
+            if (process.env.REDIS_IMAGE_CACHE === 'true') {
+                await this.redisClient.hmset(cacheKey, {
+                    extension: value.extension,
+                    maxAge: revalidate,
+                    expireAt,
+                    buffer: value.buffer.toString("base64"),
+                    etag: value.etag,
+                    upstreamEtag: value.upstreamEtag
+                })
+            } else {
+                await writeToCacheDir((0, _path.join)(this.cacheDir, cacheKey), value.extension, revalidate, expireAt, value.buffer, value.etag, value.upstreamEtag);
+            }
         } catch (err) {
             _log.error(`Failed to write image to cache ${cacheKey}`, err);
         }
diff --git a/dist/server/next-server.js b/dist/server/next-server.js
index 68b9639d21c369a1d574ed548b7953c188c1ab97..1e0542ca207b97fd500fcb4880934931f399a08a 100644
--- a/dist/server/next-server.js
+++ b/dist/server/next-server.js
@@ -62,6 +62,7 @@ const _routekind = require("./route-kind");
 const _invarianterror = require("../shared/lib/invariant-error");
 const _awaiter = require("./after/awaiter");
 const _asynccallbackset = require("./lib/async-callback-set");
+const Redis = require("ioredis");
 function _export_star(from, to) {
     Object.keys(from).forEach(function(k) {
         if (k !== "default" && !Object.prototype.hasOwnProperty.call(to, k)) {
@@ -154,7 +155,8 @@ class NextNodeServer extends _baseserver.default {
                 const { ImageOptimizerCache } = require('./image-optimizer');
                 const imageOptimizerCache = new ImageOptimizerCache({
                     distDir: this.distDir,
-                    nextConfig: this.nextConfig
+                    nextConfig: this.nextConfig,
+                    redisClient: this.redisClient
                 });
                 const { sendResponse, ImageError } = require('./image-optimizer');
                 if (!this.imageResponseCache) {
@@ -373,6 +375,11 @@ class NextNodeServer extends _baseserver.default {
             }
             return result.finished;
         };
+        this.redisClient = process.env.REDIS_IMAGE_CACHE ? new Redis({
+            host: process.env.REDIS_HOST,
+            port: parseInt(process.env.REDIS_PORT ?? "6379"),
+            password: process.env.REDIS_PASSWORD,
+        }) : null;        
         /**
      * This sets environment variable to be used at the time of SSR by head.tsx.
      * Using this from process.env allows targeting SSR by calling

Backstory: Im selfhosting Next.js on multiple vm on cloud, those vm are very small and takes a bit time and cpu for rendering the image.

By using this patch + keyDB multi master replication, Im able to sync the image cache, and restore after update the app

requirement:
only tested on next 15.1.2

install:

1. put in yarn's .yarn/patches folder
2. update next js version to patch:next@npm%3A15.1.2#~/.yarn/patches/next-npm-15.1.2-24e7411703.patch in package.json
3. run yarn

usage:
add follow env

REDIS_IMAGE_CACHE=true # setting to anything other than false will disable it
REDIS_HOST="<some ip>"
REDIS_PORT=6379
REDIS_PASSWORD="<password>"