@slack/bolt meets Fastify

app.ts

import Fastify from 'fastify';
import { App, FileInstallationStore, LogLevel } from '@slack/bolt';
import { FileStateStore } from '@slack/oauth';
import { FastifyReceiver } from 'slack-bolt-fastify';

const fastify = Fastify({ logger: true });

fastify.get('/', async (_, res) => {
  res.redirect('/slack/install');
});

const receiver = new FastifyReceiver({
  signingSecret: process.env.SLACK_SIGNING_SECRET!,
  clientId: process.env.SLACK_CLIENT_ID,
  clientSecret: process.env.SLACK_CLIENT_SECRET,
  scopes: ['commands', 'chat:write', 'app_mentions:read'],
  installationStore: new FileInstallationStore(),
  installerOptions: {
    directInstall: true,
    stateStore: new FileStateStore({}),
  },
  fastify,
});

const app = new App({
  logLevel: LogLevel.DEBUG,
  receiver,
});

app.event('app_mention', async ({ event, say }) => {
  await say({
    text: `<@${event.user}> Hi there :wave:`,
    blocks: [
      {
        type: 'section',
        text: {
          type: 'mrkdwn',
          text: `<@${event.user}> Hi there :wave:`,
        },
      },
    ],
  });
});

app.command('/my-command', async ({ ack }) => {
  await ack('Hi there!');
});

app.shortcut('my-global-shortcut', async ({ ack, body, client }) => {
  await ack();
  await client.views.open({
    trigger_id: body.trigger_id,
    view: {
      type: 'modal',
      callback_id: 'my-modal',
      title: {
        type: 'plain_text',
        text: 'My App',
      },
      submit: {
        type: 'plain_text',
        text: 'Submit',
      },
      blocks: [
        {
          type: 'input',
          block_id: 'b',
          element: {
            type: 'plain_text_input',
            action_id: 'a',
          },
          label: {
            type: 'plain_text',
            text: 'Comment',
          },
        },
      ],
    },
  });
});

app.view('my-modal', async ({ view, ack, logger }) => {
  logger.info(view.state.values);
  await ack();
});

(async () => {
  await app.start();
  // eslint-disable-next-line no-console
  console.log('⚡️ Bolt app is running!');
})();

package.json

{
  "name": "fastify-example-app",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "scripts": {
    "start": "npm run build && npx node app.js",
    "build": "tsc -p ."
  },
  "keywords": [],
  "author": "Kazuhiro Sera (@seratch)",
  "license": "MIT",
  "dependencies": {
    "@slack/bolt": "^3.11.0",
    "fastify": "^3.27.4",
    "slack-bolt-fastify": "^0.3.0",
    "ts-node": "^10.7.0",
    "typescript": "^4.6.3"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "lib": ["es6", "dom"],
    "outDir": "lib",
    "rootDir": "src",
    "strict": true,
    "esModuleInterop": true,
    "resolveJsonModule": true
  }
}