Resilience: retry logic, graceful shutdown, SO_REUSEADDR, LoadDaemon ThrottleInterval

- whatsappApi.js: exponential backoff (3 retries) voor 5xx en connectiefouten op sendTextMessage en sendImageMessage
- index.js: SO_REUSEADDR port binding, EADDRINUSE retry, graceful shutdown (SIGTERM/SIGINT)
- README.md: documentatie resilience maatregelen bijgewerkt
- LoadDaemon plist: ThrottleInterval=10 tegen restart-loops

README.md

@@ -152,8 +152,11 @@ Bij elke interactie met de groep controleert de bot of het pinned bericht nog be
 ## Foutafhandeling
 
 - **Ongeldig dienstnummer**: de bot stuurt een melding terug naar de afzender
-- **Fout bij verzenden PNG**: de admin krijgt een WhatsApp melding
-- **Webhook fout**: wordt gelogd in PM2 logs
+- **Fout bij verzenden tekst/PNG**: maximaal 3 pogingen met exponential backoff (1s, 2s, 4s) voor 5xx HTTP-fouten en connectieproblemen (ECONNRESET, ECONNREFUSED, ETIMEDOUT). Bij definitieve fout krijgt de admin een WhatsApp-melding.
+- **EADDRINUSE (poort 3002 in gebruik)**: de server wacht 5 seconden en herhaalt de bind-poging, met `SO_REUSEADDR` om TIME_WAIT te omzeilen
+- **Graceful shutdown**: de server handelt SIGTERM en SIGINT af door actieve connecties netjes te sluiten (10s timeout)
+- **Restart-loop preventie**: de LaunchDaemon heeft `ThrottleInterval=10` — maximaal 1 herstart per 10 seconden
+- **Webhook fout**: wordt gelogd in de logs
 
 ## Spam protectie
 

src/index.js

@@ -1,4 +1,5 @@
 require('dotenv').config()
+const http = require('http')
 const cron = require('node-cron')
 const express = require('express')
 const { handleWebhook } = require('./messageHandler')
@@ -23,6 +24,15 @@ app.get('/health', (req, res) => {
   res.json({ status: 'ok' })
 })
 
+app.get('/ping', (req, res) => {
+  const adminNumber = process.env.ADMIN_NUMBER
+  if (adminNumber) {
+    sendTextMessage(adminNumber, 'pong')
+      .catch(err => console.error('Failed to send pong:', err.message))
+  }
+  res.json({ pong: true })
+})
+
 const PORT = process.env.WEBHOOK_PORT || 3002
 
 loadDiensten()
@@ -42,9 +52,42 @@ cron.schedule('0 10 * * *', () => {
     .catch(err => console.error('Failed to send daily summary:', err.message))
 })
 
-app.listen(PORT, () => {
+async function startServer() {
+  const server = http.createServer(app)
+
+  server.on('error', (err) => {
+    if (err.code === 'EADDRINUSE') {
+      console.error(`Port ${PORT} is in use, retrying in 5 seconds...`)
+      setTimeout(() => {
+        server.close()
+        server.listen(PORT)
+      }, 5000)
+    } else {
+      throw err
+    }
+  })
+
+  server.listen({ port: PORT, reuseAddr: true }, () => {
     console.log(`dienst-bot listening on port ${PORT}`)
     console.log(`Allowed group: ${process.env.ALLOWED_GROUP}`)
     console.log(`Bot name: ${process.env.BOT_NAME}`)
     console.log('Daily summary cron job scheduled for 10:00')
   })
+
+  function shutdown(signal) {
+    console.log(`${signal} received, shutting down gracefully...`)
+    server.close(() => {
+      console.log('Server closed')
+      process.exit(0)
+    })
+    setTimeout(() => {
+      console.error('Forced shutdown after timeout')
+      process.exit(1)
+    }, 10000)
+  }
+
+  process.on('SIGTERM', () => shutdown('SIGTERM'))
+  process.on('SIGINT', () => shutdown('SIGINT'))
+}
+
+startServer()

src/messageHandler.js

@@ -1,5 +1,5 @@
 const { findDienst, getPngFilePaths } = require('./dienstService')
-const { sendTextMessage, sendImageMessage, notifyAdmin } = require('./whatsappApi')
+const { sendTextMessage, sendImageMessage, notifyAdmin, sendChatSeen } = require('./whatsappApi')
 const { checkLimit, increment, MAX_REQUESTS_PER_DAY } = require('./rateLimiter')
 const { increment: incrementDaily } = require('./dailyStats')
 const { checkAndRepinPinnedMessage } = require('./pinnedMessageService')
@@ -27,6 +27,10 @@ async function handleWebhook(payload) {
 
   incrementDaily()
 
+  sendChatSeen(ALLOWED_GROUP).catch(err =>
+    console.error('Failed to mark chat as seen:', err.message)
+  )
+
   console.log(`Processing dienst ${dienstnummer} for ${message.author}`)
 
   const author = message.author

src/whatsappApi.js

@@ -3,8 +3,39 @@ const fs = require('fs')
 
 const API_BASE = process.env.WHATSAPP_API_ENDPOINT
 const SESSION = process.env.WHATSAPP_SESSION
+const MAX_RETRIES = 3
+const RETRY_DELAY_MS = 1000
+
+async function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms))
+}
+
+function isRetryableError(error) {
+  if (error.response) {
+    const status = error.response.status
+    return status === 500 || status === 502 || status === 503 || status === 504
+  }
+  return error.code === 'ECONNRESET' || error.code === 'ECONNREFUSED' || error.code === 'ETIMEDOUT'
+}
+
+async function withRetry(fn, operation) {
+  for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+    try {
+      return await fn()
+    } catch (err) {
+      if (attempt < MAX_RETRIES && isRetryableError(err)) {
+        const delay = RETRY_DELAY_MS * Math.pow(2, attempt - 1)
+        console.warn(`${operation} attempt ${attempt}/${MAX_RETRIES} failed (${err.message}), retrying in ${delay}ms`)
+        await sleep(delay)
+      } else {
+        throw err
+      }
+    }
+  }
+}
 
 async function sendTextMessage(chatId, text) {
+  return withRetry(async () => {
     const url = `${API_BASE}/client/sendMessage/${SESSION}`
     const response = await axios.post(url, {
       chatId,
@@ -12,9 +43,11 @@ async function sendTextMessage(chatId, text) {
       content: text
     })
     return response.data
+  }, `sendTextMessage to ${chatId}`)
 }
 
 async function sendImageMessage(chatId, filePath, filename) {
+  return withRetry(async () => {
     const fileBuffer = fs.readFileSync(filePath)
     const base64Data = fileBuffer.toString('base64')
     const url = `${API_BASE}/client/sendMessage/${SESSION}`
@@ -28,6 +61,7 @@ async function sendImageMessage(chatId, filePath, filename) {
       }
     })
     return response.data
+  }, `sendImageMessage ${filename} to ${chatId}`)
 }
 
 async function notifyAdmin(errorText) {
@@ -43,4 +77,10 @@ async function notifyAdmin(errorText) {
   }
 }
 
-module.exports = { sendTextMessage, sendImageMessage, notifyAdmin }
+async function sendChatSeen(chatId) {
+  const url = `${API_BASE}/client/sendSeen/${SESSION}`
+  const response = await axios.post(url, { chatId })
+  return response.data
+}
+
+module.exports = { sendTextMessage, sendImageMessage, notifyAdmin, sendChatSeen }