创建GitHub webhook

什么是webhook

Webhook 是一个 API 概念，是微服务 API 的使用范式之一，也被成为反向 API，即前端不主动发送请求，完全由后端推送;

GtiHub中就存在这种功能，通过创建一个GitHub的webhook可以实现项目的自动部署，issues的自动推送等功能;

如何创建GitHub的webhook

首先我们要了解它的工作流程：

编写webhook接口

此处以nest.js创建的接口为例

// webhook.controller.ts
import {
  Controller,
  HttpException,
  HttpStatus,
  Logger,
  Post,
  Req,
} from '@nestjs/common';
import { Request } from 'express';
import * as crypto from 'crypto';

import { WebhooksService } from './webhooks.service';
import { ConfigService } from 'src/config/config.service';

@Controller('webhooks')
export class WebhooksController {
  private Logger = new Logger(WebhooksController.name);
  constructor(
    private readonly webhooksService: WebhooksService,
    private readonly config: ConfigService,
  ) {}
  /**
   * 校验github webhook设置的secret的方法
   **/
  private verify_signature(req: Request, deploy: string) {
    if (!req.headers['x-hub-signature-256']) {
      return false;
    }
    const signature = crypto
      .createHmac(
        'sha256',
        this.config[
          `webhookSecret${deploy.replace(/^\S/, (s) => s.toUpperCase())}`
        ],
      )
      .update(JSON.stringify(req.body))
      .digest('hex');
    const trusted = Buffer.from(`sha256=${signature}`, 'ascii');
    const untrusted = Buffer.from(
      req.headers['x-hub-signature-256'] as string,
      'ascii',
    );
    return crypto.timingSafeEqual(trusted, untrusted);
  }

  private deployHandler(req: Request, deploy: string) {
    if (!this.verify_signature(req, deploy)) {
      this.Logger.error('Unauthorized');
      this.Logger.error(`headers: \n${JSON.stringify(req.headers)}`);
      this.Logger.error(`body: \n${JSON.stringify(req.body)}`);
      throw new HttpException('Unauthorized', HttpStatus.UNAUTHORIZED);
    }
    if (req.headers['x-github-event'] === 'push') {
      return {
        message: this.webhooksService[`${deploy}Deploy`](),
        statusCode: 200,
      };
    }
    // 这里是github webhook 发送除了push之外请求时的返回，如果有需要自行判断事件类型进行处理
    return {
      message: 'webhook no handler',
      statusCode: 200,
    };
  }

  @Post('blog')
  blog(@Req() req: Request) {
    return this.deployHandler(req, 'blog');
  }
}

// webhook.service.ts
import { Injectable, Logger } from '@nestjs/common';
import { spawn } from 'child_process';

@Injectable()
export class WebhooksService {
  private readonly Logger = new Logger(WebhooksService.name);

  constructor() {
    this.Logger.log('webhooks create...');
  }

  blogDeploy() {
    this.Logger.log('deploy init');
    // 启动子进程
    const deploy = spawn('sh', ['scripts/blog.deploy.sh']); // 执行构建脚本
    deploy.stdout.on('data', (data) => {
      this.Logger.log(data);
    });
    deploy.stderr.on('data', (data) => {
      this.Logger.log(data);
    });
    deploy.stdout.on('end', () => {
      this.Logger.log('deploy end');
    });

    deploy.stdout.on('error', (err) => {
      this.Logger.error(err);
    });
    // 我这里不管子进程执行进度，直接返回成功，想同步执行的自己改
    return 'success';
  }
}

创建github webhook