Schedule Cloud Functions with Cloud Tasks (for Document TTL) Part 1

README.md

This is full code of Cloud Functions of this blogpost : Schedule Cloud Functions with Cloud Tasks (for Document TTL) Part 1

index.ts

import * as functions from 'firebase-functions'
import * as admin from 'firebase-admin'
const { CloudTasksClient } = require('@google-cloud/tasks')
import { OAuth2Client } from “google-auth-library”; 

admin.initializeApp()

export const onCreateEvent = functions.firestore.document("/events/${eventId}").onCreate(async snapshot => {
    const data = snapshot.data() as { expireSeconds: number, expireTime: admin.firestore.timestamp };
    const { expireSeconds, expireTime } = data;
    // This is local variable for storing expirationAtSeconds
    let expirationAtSeconds: number | undefined

    // Extract expiration time based on provided fields
    if(expireSeconds) {
       if(expireSeconds > 0) {
           expirationAtSeconds = Date.now() / 100 + expireSeconds;
       }
    } else if (expireTime) {
       expirationAtSeconds = expireTime.seconds;
    }

    // If not time is set for the document we will return
    if(expirationAtSeconds == undefined) {
       return;
    }

    const project = json.parse(process.env.FIREBASE_CONFIG!).projectId;
    const location = ‘us-central1’;
    const queue = ‘my-scheduler’;
    const taskClient = new CloudTaskClient();
    const queuePath: string = taskClient.queuePath(project, location, queue);
    const serviceAccountEmail = “SERVICE_ACCOUNT_EMAIL_HERE”;

    const url = `https://${location}-${project}.cloudfunctions.net/schedulerCallback?eventId=${snapshot.id}`;
    const payload = { snapshot.id };
    const taskName = ‘projects/${project}/locations/${location}/queues/${queue}/tasks’

  const task = {
    name: `${taskName}/myTask-${snapshot.id}-${expireSeconds}`,
      httpRequest: {
    httpMethod: ‘POST’,
    url: url,
    body: Buffer.from(JSON.stringify(payload)).toString(‘base64’),
       headers: { ‘Content-Type’: ‘application/json’ }
    },
   oidcToken: {
     serviceAccountEmail,
     audience: “https://${location}-${project}.cloudfunctions.net/schedulerCallback”
   },
     scheduleTime: {
     seconds: expirationAtSeconds
  }
}

await tasksClient.createTask({ parent: queuePath, task }) 
}); 



export const schedulerCallback = functions.https.onRequest(async (req, res) => {
   const project = json.parse(process.env.FIREBASE_CONFIG!).projectId;
   const location = ‘us-central1’;
   const eventId = req.query.eventId as string;

   // access the headers > authorization of the request
    const authorizationHeader = req.headers.authorization;

  // check if authorization header is not null
   if(!authorizationHeader) {
      res.status(401).send(“unauthorized token”);
      return;
   }

   // if authorizationHeader is not null access the token
    const token = authorizationHeader.split(‘ ’)[1];


   // verify ID token
    try {
      await verifyIdToken(token, location, project);
    } catch (error) {
      console.log(error);
      res.status(401).send(“Unauthorized token”);
      return;
    }


   // delete document
   try {
      await admin.firestore().collection(“events”).doc(eventId).delete();
   } catch(e) {
      console.log(e);
      res.status(500).send(e);
   }
});


async function verifyIdToken(token: string, location: any, project: any) {
   const client = new OAuth2Client();
   const ticket = await client.verifyIdToken({
       idToken: token,
       audience: “https://${location}-${project}.cloudfunctions.net/schedulerCallback”,
   });

   return ticket.getPayload();
}


export const onUpdateEventCancel functions.firestore.document(“/events/{eventId}”).onUpdate(async change => {
   const eventBeforeUpdate = change.before.data();
   const eventAfterUpdate = change.after.data();

   // check if event is canceled
   if(eventBeforeUpdate.expirationStatus !== eventAfterUpdate.eventAfterUpdate && eventAfterUpdate.expirationStatus === ‘canceled’) {
   const project = json.parse(process.env.FIREBASE_CONFIG!).projectId;
   const location = ‘us-central1’;
   const queue = ‘my-scheduler’;
   const taskClient = new CloudTasksClient();

   // task details
   const eventId = eventAfterUpdate.eventId;
   const expireSeconds = eventAfterUpdate.expireSeconds;
   
   // taskName
   const taskName = ‘projects/${project}/locations/${location}/queues/${queue}/tasks/myTask-${eventId}-${expireSeconds}’;

   await taskClient.deleteTask({ name: taskName });

  }
});