feat(clsi): add compile heartbeat to avoid CDN timeout

Author: Makiras

services/clsi/app/js/CompileController.js

@@ -9,11 +9,56 @@ const Errors = require('./Errors')
 const { notifyCLSICacheAboutBuild } = require('./CLSICacheHandler')
 
 let lastSuccessfulCompileTimestamp = 0
+const COMPILE_HEARTBEAT_INTERVAL_MS =
+  Settings.clsi?.compileHeartbeatMs ?? 10 * 1000
 
 function timeSinceLastSuccessfulCompile() {
   return Date.now() - lastSuccessfulCompileTimestamp
 }
 
+// Send interim 102 responses so upstream proxies/CDNs don't drop long-running compile requests.
+// We use writeProcessing() because it does not lock in the final HTTP status code.
+function startCompileHeartbeat(res) {
+  const writeProcessing = res.writeProcessing?.bind(res)
+  if (!writeProcessing || COMPILE_HEARTBEAT_INTERVAL_MS <= 0) {
+    return () => {}
+  }
+
+  let stopped = false
+  let timer
+
+  const stop = () => {
+    if (stopped) return
+    stopped = true
+    if (timer) clearInterval(timer)
+    if (typeof res.removeListener === 'function') {
+      res.removeListener('close', stop)
+      res.removeListener('finish', stop)
+    }
+  }
+
+  const ping = () => {
+    if (stopped || res.writableEnded) {
+      stop()
+      return
+    }
+    try {
+      writeProcessing()
+    } catch (err) {
+      logger.debug({ err }, 'failed to send compile heartbeat')
+      stop()
+    }
+  }
+
+  ping()
+  timer = setInterval(ping, COMPILE_HEARTBEAT_INTERVAL_MS)
+  if (typeof res.on === 'function') {
+    res.on('close', stop)
+    res.on('finish', stop)
+  }
+  return stop
+}
+
 function compile(req, res, next) {
   const timer = new Metrics.Timer('compile-request')
   RequestParser.parse(req.body, function (error, request) {
@@ -31,13 +76,15 @@ function compile(req, res, next) {
         if (error) {
           return next(error)
         }
+        const stopHeartbeat = startCompileHeartbeat(res)
         const stats = {}
         const timings = {}
         CompileManager.doCompileWithLock(
           request,
           stats,
           timings,
           (error, result) => {
+            stopHeartbeat()
             let { buildId, outputFiles } = result || {}
             let code, status
             if (outputFiles == null) {

services/clsi/config/settings.defaults.js

@@ -121,6 +121,9 @@ module.exports.clsi = {
   optimiseInDocker: true,
   expireProjectAfterIdleMs: 24 * 60 * 60 * 1000,
   checkProjectsIntervalMs: 10 * 60 * 1000,
+  // Interval (ms) to send HTTP 102 Processing during long compiles to keep proxies/CDNs alive
+  compileHeartbeatMs:
+    parseInt(process.env.COMPILE_HEARTBEAT_MS, 10) || 10 * 1000,
   // Validate host sandboxed compiles path from Docker daemon perspective when the
   // configured host path is not visible inside this container. This is useful in
   // development setups where host paths are mounted differently; set to 'false'