feat: Make task runners work with n8n from npm (no-changelog) (#11015)

packages/cli/src/runners/task-runner-process.ts

@@ -0,0 +1,89 @@
+import { GlobalConfig } from '@n8n/config';
+import * as a from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { Service } from 'typedi';
+
+import { TaskRunnerAuthService } from './auth/task-runner-auth.service';
+import { OnShutdown } from '../decorators/on-shutdown';
+
+type ChildProcess = ReturnType<typeof spawn>;
+
+/**
+ * Manages the JS task runner process as a child process
+ */
+@Service()
+export class TaskRunnerProcess {
+	public get isRunning() {
+		return this.process !== null;
+	}
+
+	/** The process ID of the task runner process */
+	public get pid() {
+		return this.process?.pid;
+	}
+
+	private process: ChildProcess | null = null;
+
+	/** Promise that resolves after the process has exited */
+	private runPromise: Promise<void> | null = null;
+
+	private isShuttingDown = false;
+
+	constructor(
+		private readonly globalConfig: GlobalConfig,
+		private readonly authService: TaskRunnerAuthService,
+	) {}
+
+	async start() {
+		a.ok(!this.process, 'Task Runner Process already running');
+
+		const grantToken = await this.authService.createGrantToken();
+		const startScript = require.resolve('@n8n/task-runner');
+
+		this.process = spawn('node', [startScript], {
+			env: {
+				PATH: process.env.PATH,
+				N8N_RUNNERS_GRANT_TOKEN: grantToken,
+				N8N_RUNNERS_N8N_URI: `localhost:${this.globalConfig.port}`,
+			},
+		});
+
+		this.process.stdout?.pipe(process.stdout);
+		this.process.stderr?.pipe(process.stderr);
+
+		this.monitorProcess(this.process);
+	}
+
+	@OnShutdown()
+	async stop() {
+		if (!this.process) {
+			return;
+		}
+
+		this.isShuttingDown = true;
+
+		// TODO: Timeout & force kill
+		this.process.kill();
+		await this.runPromise;
+
+		this.isShuttingDown = false;
+	}
+
+	private monitorProcess(process: ChildProcess) {
+		this.runPromise = new Promise((resolve) => {
+			process.on('exit', (code) => {
+				this.onProcessExit(code, resolve);
+			});
+		});
+	}
+
+	private onProcessExit(_code: number | null, resolveFn: () => void) {
+		this.process = null;
+		resolveFn();
+
+		// If we are not shutting down, restart the process
+		if (!this.isShuttingDown) {
+			setImmediate(async () => await this.start());
+		}
+	}
+}