Ryan Cohen
2 years ago
committed by
sct
parent
bfe56c3470
commit
063beea2ca
@ -0,0 +1,185 @@
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import logger from '@server/logger';
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import axios from 'axios';
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import rateLimit, { type rateLimitOptions } from 'axios-rate-limit';
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import { createHash } from 'crypto';
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import { promises } from 'fs';
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import path, { join } from 'path';
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type ImageResponse = {
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meta: {
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revalidateAfter: number;
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curRevalidate: number;
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isStale: boolean;
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etag: string;
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extension: string;
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cacheKey: string;
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cacheMiss: boolean;
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};
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imageBuffer: Buffer;
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};
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class ImageProxy {
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private axios;
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private cacheVersion;
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private key;
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constructor(
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key: string,
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baseUrl: string,
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options: {
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cacheVersion?: number;
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rateLimitOptions?: rateLimitOptions;
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} = {}
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) {
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this.cacheVersion = options.cacheVersion ?? 1;
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this.key = key;
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this.axios = axios.create({
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baseURL: baseUrl,
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});
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if (options.rateLimitOptions) {
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this.axios = rateLimit(this.axios, options.rateLimitOptions);
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}
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}
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public async getImage(path: string): Promise<ImageResponse> {
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const cacheKey = this.getCacheKey(path);
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const imageResponse = await this.get(cacheKey);
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if (!imageResponse) {
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const newImage = await this.set(path, cacheKey);
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if (!newImage) {
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throw new Error('Failed to load image');
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}
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return newImage;
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}
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// If the image is stale, we will revalidate it in the background.
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if (imageResponse.meta.isStale) {
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this.set(path, cacheKey);
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}
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return imageResponse;
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}
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private async get(cacheKey: string): Promise<ImageResponse | null> {
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try {
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const directory = join(this.getCacheDirectory(), cacheKey);
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const files = await promises.readdir(directory);
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const now = Date.now();
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for (const file of files) {
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const [maxAgeSt, expireAtSt, etag, extension] = file.split('.');
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const buffer = await promises.readFile(join(directory, file));
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const expireAt = Number(expireAtSt);
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const maxAge = Number(maxAgeSt);
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return {
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meta: {
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curRevalidate: maxAge,
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revalidateAfter: maxAge * 1000 + now,
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isStale: now > expireAt,
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etag,
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extension,
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cacheKey,
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cacheMiss: false,
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},
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imageBuffer: buffer,
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};
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}
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} catch (e) {
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// No files. Treat as empty cache.
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}
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return null;
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}
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private async set(
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path: string,
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cacheKey: string
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): Promise<ImageResponse | null> {
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try {
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const directory = join(this.getCacheDirectory(), cacheKey);
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const response = await this.axios.get(path, {
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responseType: 'arraybuffer',
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});
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const buffer = Buffer.from(response.data, 'binary');
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const extension = path.split('.').pop() ?? '';
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const maxAge = Number(response.headers['cache-control'].split('=')[1]);
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const expireAt = Date.now() + maxAge * 1000;
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const etag = response.headers.etag.replace(/"/g, '');
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await this.writeToCacheDir(
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directory,
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extension,
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maxAge,
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expireAt,
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buffer,
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etag
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);
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return {
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meta: {
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curRevalidate: maxAge,
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revalidateAfter: expireAt,
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isStale: false,
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etag,
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extension,
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cacheKey,
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cacheMiss: true,
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},
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imageBuffer: buffer,
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};
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} catch (e) {
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logger.debug('Something went wrong caching image.', {
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label: 'Image Cache',
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errorMessage: e.message,
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});
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return null;
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}
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}
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private async writeToCacheDir(
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dir: string,
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extension: string,
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maxAge: number,
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expireAt: number,
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buffer: Buffer,
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etag: string
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) {
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const filename = join(dir, `${maxAge}.${expireAt}.${etag}.${extension}`);
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await promises.rm(dir, { force: true, recursive: true }).catch(() => {
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// do nothing
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});
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await promises.mkdir(dir, { recursive: true });
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await promises.writeFile(filename, buffer);
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}
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private getCacheKey(path: string) {
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return this.getHash([this.key, this.cacheVersion, path]);
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}
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private getHash(items: (string | number | Buffer)[]) {
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const hash = createHash('sha256');
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for (const item of items) {
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if (typeof item === 'number') hash.update(String(item));
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else {
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hash.update(item);
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}
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}
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// See https://en.wikipedia.org/wiki/Base64#Filenames
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return hash.digest('base64').replace(/\//g, '-');
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}
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private getCacheDirectory() {
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return path.join(__dirname, '../../config/cache/images/', this.key);
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}
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}
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export default ImageProxy;
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@ -0,0 +1,39 @@
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import ImageProxy from '@server/lib/imageproxy';
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import logger from '@server/logger';
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import { Router } from 'express';
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const router = Router();
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const tmdbImageProxy = new ImageProxy('tmdb', 'https://image.tmdb.org', {
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rateLimitOptions: {
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maxRequests: 20,
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maxRPS: 50,
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},
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});
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/**
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* Image Proxy
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*/
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router.get('/*', async (req, res) => {
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const imagePath = req.path.replace('/image', '');
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try {
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const imageData = await tmdbImageProxy.getImage(imagePath);
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res.writeHead(200, {
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'Content-Type': `image/${imageData.meta.extension}`,
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'Content-Length': imageData.imageBuffer.length,
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'Cache-Control': `public, max-age=${imageData.meta.curRevalidate}`,
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'OS-Cache-Key': imageData.meta.cacheKey,
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'OS-Cache-Status': imageData.meta.cacheMiss ? 'MISS' : 'HIT',
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});
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res.end(imageData.imageBuffer);
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} catch (e) {
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logger.error('Failed to proxy image', {
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imagePath,
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errorMessage: e.message,
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});
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res.status(500).send();
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}
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});
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export default router;
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