Genkit MCP

/** * Copyright 2024 Google LLC * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import { ChildProcess, spawn } from 'child_process'; import terminate from 'terminate'; import { logger } from '../utils'; export type ProcessStatus = 'running' | 'stopped' | 'unconfigured'; export interface AppProcessStatus { status: ProcessStatus; } export interface ProcessManagerStartOptions { nonInteractive?: boolean; } /** * Manages a child process. */ export class ProcessManager { private appProcess?: ChildProcess; private originalStdIn?: NodeJS.ReadStream; private _status: ProcessStatus = 'stopped'; private manualRestart = false; constructor( private readonly command: string, private readonly args: string[], private readonly env: NodeJS.ProcessEnv = {} ) {} /** * Starts the process. */ start(options?: ProcessManagerStartOptions): Promise<void> { return new Promise((resolve, reject) => { this._status = 'running'; this.appProcess = spawn(this.command, this.args, { env: { ...process.env, ...this.env, }, shell: process.platform === 'win32', }); if (!options?.nonInteractive) { this.originalStdIn = process.stdin; this.appProcess.stderr?.pipe(process.stderr); this.appProcess.stdout?.pipe(process.stdout); process.stdin?.pipe(this.appProcess.stdin!); } this.appProcess.on('error', (error): void => { logger.error(`Error in app process: ${error}`); this.cleanup(); reject(error); }); this.appProcess.on('exit', (code, signal) => { this.cleanup(); if (this.manualRestart) { this.manualRestart = false; return; } // If the process was killed by a signal, it's not an error in this context. if (code === 0 || signal) { resolve(); } else { reject(new Error(`app process exited with code ${code}`)); } }); }); } /** * Kills the currently-running process and starts a new one. */ async restart(options?: ProcessManagerStartOptions): Promise<void> { this.manualRestart = true; await this.kill(); this.start(options).catch(() => {}); } /** * Kills the currently-running process. */ kill(): Promise<void> { return new Promise((resolve) => { if (!this.appProcess || !this.appProcess.pid || this.appProcess.killed) { this._status = 'stopped'; resolve(); return; } // The 'exit' listener is set up in start() and will handle cleanup. this.appProcess.on('exit', () => { resolve(); }); terminate(this.appProcess.pid, 'SIGTERM', (err) => { if (err) { // This can happen if the process is already gone, which is fine. logger.debug(`Error during process termination: ${err.message}`); } resolve(); }); }); } status(): AppProcessStatus { return { status: this._status, }; } private cleanup() { if (this.originalStdIn) { process.stdin.unpipe(this.appProcess?.stdin!); this.originalStdIn = undefined; } if (this.appProcess) { this.appProcess.stdout?.unpipe(process.stdout); this.appProcess.stderr?.unpipe(process.stderr); } this.appProcess = undefined; this._status = 'stopped'; } }