Upload files to "/"

Dockerfile

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+FROM node:20-alpine
+WORKDIR /app
+COPY server.js ./
+COPY public ./public
+RUN mkdir -p data && chown -R node:node /app
+USER node
+EXPOSE 3000
+CMD ["node","server.js"]

compose.yml

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+services:
+  signup:
+    build: .
+    ports:
+      - "8080:3000"
+    volumes:
+      - ./data:/app/data
+    restart: unless-stopped

server.js

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+import { createServer } from 'http';
+import { appendFile, mkdir, readFile, stat } from 'fs/promises';
+import { existsSync, createReadStream } from 'fs';
+import { resolve, extname } from 'path';
+
+const PORT = process.env.PORT || 3000;
+const HOST = '0.0.0.0';
+const PUBLIC_DIR = resolve('./public');
+const DATA_DIR = resolve('./data');
+const CSV = resolve(DATA_DIR, 'signups.csv');
+const emailSet = new Set();
+
+const mime = { '.html':'text/html','.js':'application/javascript','.css':'text/css' };
+
+async function ensureFile() {
+  await mkdir(DATA_DIR, { recursive:true });
+  if(!existsSync(CSV)) await appendFile(CSV, 'timestamp,email\n');
+}
+
+function validEmail(e){return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(e);}
+
+async function serveFile(path, res){
+  try{
+    const st=await stat(path);
+    res.writeHead(200,{'Content-Type':mime[extname(path)]||'text/plain'});
+    createReadStream(path).pipe(res);
+  }catch{res.writeHead(404).end('Not found');}
+}
+
+createServer(async (req,res)=>{
+  if(req.url==='/api/subscribe' && req.method==='POST'){
+    let body='';for await(const c of req)body+=c;
+    try{
+      const {email}=JSON.parse(body);
+      if(!validEmail(email)){res.writeHead(400).end('Invalid');return;}
+      if(emailSet.has(email)){res.writeHead(200).end('OK');return;}
+      const line=`${new Date().toISOString()},${email}\n`;
+      await appendFile(CSV,line);emailSet.add(email);
+      res.writeHead(200).end('Saved');
+    }catch{res.writeHead(500).end('Error');}
+    return;
+  }
+  const path = req.url==='/'?resolve(PUBLIC_DIR,'index.html'):resolve(PUBLIC_DIR,req.url.slice(1));
+  serveFile(path,res);
+}).listen(PORT,HOST,async()=>{
+  await ensureFile();
+  console.log(`Running on http://${HOST}:${PORT}`);
+});