Initial import of verae-fleet from zapier monorepo

src/agent.js

@@ -0,0 +1,86 @@
+#!/usr/bin/env node
+/**
+ * Remote host agent: spawn/kill fleet workers so the control plane can spread replicas.
+ *
+ *   FLEET_AGENT_PORT=3851 node src/agent.js
+ *
+ * Bind loopback or a private interface. Do not publish NATS.
+ */
+import http from 'node:http';
+import { spawn } from 'node:child_process';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const WORKER = path.join(path.dirname(fileURLToPath(import.meta.url)), 'worker.js');
+const PORT = Number(process.env.FLEET_AGENT_PORT || 3851);
+const BIND = process.env.FLEET_AGENT_BIND || '127.0.0.1';
+const children = new Map();
+
+function json(res, code, obj) {
+  res.writeHead(code, { 'content-type': 'application/json' });
+  res.end(JSON.stringify(obj));
+}
+
+async function readBody(req) {
+  const chunks = [];
+  for await (const c of req) chunks.push(c);
+  const raw = Buffer.concat(chunks).toString('utf8');
+  return raw ? JSON.parse(raw) : {};
+}
+
+export function startAgent({ port = PORT, bind = BIND } = {}) {
+  const server = http.createServer(async (req, res) => {
+    const url = new URL(req.url, `http://${bind}:${port}`);
+    try {
+      if (req.method === 'GET' && url.pathname === '/health') {
+        return json(res, 200, {
+          ok: true,
+          role: 'fleet-agent',
+          workers: [...children.keys()],
+        });
+      }
+      if (req.method === 'POST' && url.pathname === '/spawn') {
+        const body = await readBody(req);
+        const instance = body.instance;
+        if (!instance) return json(res, 400, { error: 'instance required' });
+        if (children.has(instance)) {
+          return json(res, 200, { pid: children.get(instance).pid, instance, existing: true });
+        }
+        const child = spawn(process.execPath, [WORKER], {
+          env: { ...process.env, ...(body.env || {}) },
+          stdio: ['ignore', 'pipe', 'pipe'],
+        });
+        children.set(instance, child);
+        child.on('exit', () => children.delete(instance));
+        return json(res, 200, { pid: child.pid, instance });
+      }
+      if (req.method === 'POST' && url.pathname === '/kill') {
+        const body = await readBody(req);
+        const child = children.get(body.instance);
+        if (child) {
+          child.kill('SIGTERM');
+          children.delete(body.instance);
+        }
+        return json(res, 200, { killed: Boolean(child), instance: body.instance });
+      }
+      json(res, 404, { error: 'not found' });
+    } catch (err) {
+      json(res, 400, { error: err.message });
+    }
+  });
+  server.listen(port, bind, () => {
+    process.stdout.write(`fleet-agent http://${bind}:${port}/\n`);
+  });
+  return {
+    server,
+    async close() {
+      for (const c of children.values()) c.kill('SIGTERM');
+      children.clear();
+      await new Promise((r) => server.close(r));
+    },
+  };
+}
+
+if (process.argv[1] && path.basename(process.argv[1]) === 'agent.js') {
+  startAgent();
+}