Add OAuth support to bolt

Description

Let’s add OAuth support to bolt!

It can use the new OAuth package we’ve been developing at https://github.com/slackapi/node-slack-sdk/pull/963.

The idea being, when you are initializing your app, by passing in a few new options, bolt would automatically setup a route for direct install and a route for oauth redirect. It would also take care of creating a state param for you and exchanging that + the code for an access token. Lastly, it will provide an interface to plug your own database solution to store and retrieve access tokens and other installation related info.

const app = new App({
  signingSecret: process.env.SLACK_SIGNING_SECRET,
  clientId: process.env.SLACK_CLIENT_ID,
  clientSecret: process.env.SLACK_CLIENT_SECRET,
  stateSecret: 'my-state-secret',
  scopes: ['channels:read', 'groups:read', 'channels:manage', 'chat:write'],
  metadata: 'some_metadata',
});

What type of issue is this? (place an x in one of the [ ])

• enhancement (feature request)

Requirements (place an x in each of the [ ])

• I’ve read and understood the Contributing guidelines and have done my best effort to follow them.
• I’ve read and agree to the Code of Conduct.
• I’ve searched for any related issues and avoided creating a duplicate issue.

[stevengill]

@realappie see my answer at https://github.com/slackapi/bolt-js/issues/583#issuecomment-675636574

[realappie]

@stevengill Do you have a fully working example of this anywhere? I pretty much wrote everything in the documentation regarding oauth here. Without any success 😕 I have also tried the install link without any success. I also currently have a working setup with a custom express route, but would love to switch over to the built-in implementation.

My custom implementation

This is perhaps useful to share for anyone that can't get the built-in implementation to work either.

export const createSlackAuthServer = (slackExpressReceiver: ExpressReceiver, slackApp: App, firestore: FirebaseFirestore.Firestore) => {

 const app_express = slackExpressReceiver.app;

 /* oauth callback function */
 app_express.get('/auth', async (req, res, next) => {

   const code: string = req.query['code'] as string;

   if (isNil(code)) {
     res.status(500).send('No code query param found');
   }

   try {
     const result = await slackApp.client.oauth.v2.access({
       client_id: config.slack.client_id,
       client_secret: config.slack.client_secret,
       code: code
     });

     const teamId: string = get(result, 'team.id') as string;

     const accessToken = get(result, 'access_token') as string;

     const authTestResponse: unknown = await slackApp.client.auth.test({
       token: accessToken
     });

     const authTestResponseTyped = authTestResponse as SlackAuthTestResponse;

     const installationDocument: SlackInstallationDocument = {
       botId: authTestResponseTyped.bot_id,
       teamId,
       botUserId: get(result, 'bot_user_id') as string,
       botToken: accessToken,
       user_id: authTestResponseTyped.user_id,
     };

     const installingUserId = get(result, 'authed_user.id') as string;

     const enterpriseId = get(result, 'enterprise.id') as string;

     if (enterpriseId) {
       installationDocument.enterprise_id = enterpriseId;
     }

     await firestore.collection('installations').doc(teamId).set(installationDocument);

     // Open up the conversation in slack upon success
     //
     res.redirect(`https://slack.com/app_redirect?app=${config.slack.app_id}`)

     await slackApp.client.chat.postMessage({
       token: accessToken,
       channel: installingUserId,
       text: '',
       blocks: [{
           "type": "section",
           "text": {
             "type": "mrkdwn",
             "text": `Hi there! Welcome to the bitrise bot. To start using this bot please set a bitrise access token first.`
           }
         },
         slackBlockCreator.generateSetBitriseTokenModalActionBlock()
       ]
     });

     console.error(`[slack-auth] installation successful for teamId="${teamId}" enterpriseId="${enterpriseId}"`);
   } catch (error) {
     console.error('[slack-auth] error calling client.oauth.v2.access', error);

     res.status(500).send('Error authenticating');
   }
 });
}

And wherever you’re creating a new slack App do the following

const slackExpressReceiver = new ExpressReceiver({
  signingSecret: config.slack.signing_secret,
  endpoints: '/events'
});


const slackApp = new App({
  receiver: slackExpressReceiver,
  authorize: async ({ teamId }) => {
    const documentSnapshot = await firestore.collection('installations').doc(teamId).get();

    if ( !documentSnapshot.exists ) {
      throw new Error(`no matching installations for team="${teamId}"`);
    } else {
      console.log(`[slackApp:authorize] matching installations found for teamId="${teamId}"`)
    }

    const installation = documentSnapshot.data() as SlackInstallationDocument;

    return installation;
  }
});

createSlackAuthServer(slackExpressReceiver, slackApp, firestore);