Initial import of verae-keep from zapier monorepo

src/watch.js

@@ -0,0 +1,115 @@
+#!/usr/bin/env node
+/**
+ * Backup for verae-keep. If keep's /health fails, spawn keep again.
+ */
+import { spawn } from 'node:child_process';
+import fs from 'node:fs';
+import http from 'node:http';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { httpProbe } from './probe.js';
+import { killPid, pidAlive } from './spawn.js';
+import { expandHome } from './expand.js';
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const ROOT = path.join(HERE, '..');
+const KEEP_URL = (process.env.KEEP_URL || 'http://127.0.0.1:3860').replace(/\/$/, '');
+const STATE_DIR = expandHome(process.env.KEEP_STATE || path.join(ROOT, 'data'));
+const PID_FILE = path.join(STATE_DIR, 'keep.pid');
+const INTERVAL = Number(process.env.WATCH_INTERVAL_MS || 2000);
+const BIND = process.env.WATCH_BIND || '127.0.0.1';
+const PORT = Number(process.env.WATCH_PORT || 3861);
+
+let child = null;
+let restarts = 0;
+
+function log(event, extra = {}) {
+  const line = JSON.stringify({ t: new Date().toISOString(), event, ...extra });
+  fs.mkdirSync(STATE_DIR, { recursive: true });
+  fs.appendFileSync(path.join(STATE_DIR, 'watch.log'), `${line}\n`);
+  process.stdout.write(`${line}\n`);
+}
+
+function readPid() {
+  try {
+    return Number(fs.readFileSync(PID_FILE, 'utf8').trim());
+  } catch {
+    return null;
+  }
+}
+
+function writePid(pid) {
+  fs.mkdirSync(STATE_DIR, { recursive: true });
+  fs.writeFileSync(PID_FILE, String(pid));
+}
+
+function startKeep() {
+  const existing = readPid();
+  if (existing && pidAlive(existing)) {
+    log('adopt', { pid: existing });
+    return existing;
+  }
+  const env = { ...process.env };
+  const proc = spawn(process.execPath, [path.join(HERE, 'keep.js')], {
+    cwd: ROOT,
+    env,
+    detached: true,
+    stdio: ['ignore', 'pipe', 'pipe'],
+  });
+  proc.unref();
+  child = proc;
+  writePid(proc.pid);
+  restarts += 1;
+  log('start-keep', { pid: proc.pid, restarts });
+  proc.stdout?.on('data', (c) => process.stdout.write(c));
+  proc.stderr?.on('data', (c) => process.stderr.write(c));
+  proc.on('exit', (code, signal) => {
+    log('keep-exit', { code, signal, pid: proc.pid });
+    if (readPid() === proc.pid) {
+      try {
+        fs.unlinkSync(PID_FILE);
+      } catch {
+        /* ignore */
+      }
+    }
+  });
+  return proc.pid;
+}
+
+async function tick() {
+  const h = await httpProbe(`${KEEP_URL}/health`, { timeoutMs: 1500 });
+  if (h.ok) return { ok: true, keep: h.body };
+  log('keep-down', { error: h.error || h.statusCode });
+  const old = readPid();
+  if (old && pidAlive(old)) killPid(old, 'SIGTERM');
+  startKeep();
+  return { ok: false, restarted: true };
+}
+
+const server = http.createServer(async (req, res) => {
+  const url = new URL(req.url || '/', `http://127.0.0.1:${PORT}`);
+  const json = (code, obj) => {
+    res.writeHead(code, { 'content-type': 'application/json' });
+    res.end(JSON.stringify(obj));
+  };
+  if (url.pathname === '/health') {
+    return json(200, { ok: true, role: 'verae-keep-watch', pid: process.pid, keepPid: readPid(), restarts });
+  }
+  if (url.pathname === '/tick' && req.method === 'POST') {
+    return json(200, await tick());
+  }
+  json(404, { error: 'not found' });
+});
+
+server.listen(PORT, BIND, () => {
+  log('listen', { url: `http://${BIND}:${PORT}/`, keep: KEEP_URL });
+  startKeep();
+  setInterval(() => {
+    tick().catch((err) => log('tick-error', { error: err.message }));
+  }, INTERVAL);
+});
+
+process.on('SIGTERM', () => {
+  if (child?.pid) killPid(child.pid, 'SIGTERM');
+  process.exit(0);
+});