Google Cloud Tasks: How to update a tasks time to live? - node.js

Question

Description:
I have created a Firebase app where a user can insert a Firestore document. When this document is created a timestamp is added so that it can be automatically deleted after x amount of time, by a cloud function.
After the document is created, a http/onCreate cloud function is triggered successfully, and it creates a cloud task. Which then deletes the document on the scheduled time.
export const onCreatePost = functions
.region(region)
.firestore.document('/boxes/{id}')
.onCreate(async (snapshot) => {
const data = snapshot.data() as ExpirationDocData;
// Box creation timestamp.
const { timestamp } = data;
// The path of the firebase document('/myCollection/{docId}').
const docPath = snapshot.ref.path;
await scheduleCloudTask(timestamp, docPath)
.then(() => {
console.log('onCreate: cloud task created successfully.');
})
.catch((error) => {
console.error(error);
});
});
export const scheduleCloudTask = async (timestamp: number, docPath: string) => {
// Convert timestamp to seconds.
const timestampToSeconds = timestamp / 1000;
// Doc time to live in seconds
const documentLifeTime = 20;
const expirationAtSeconds = timestampToSeconds + documentLifeTime;
// The Firebase project ID.
const project = 'my-project';
// Cloud Tasks -> firestore time to life queue.
const queue = 'my-queue';
const queuePath: string = tasksClient.queuePath(project, region, queue);
// The url to the callback function.
// That gets envoked by Google Cloud tasks when the deadline is reached.
const url = `https://${region}-${project}.cloudfunctions.net/callbackFn`;
const payload: ExpirationTaskPayload = { docPath };
// Google cloud IAM & ADMIN principle account.
const serviceAccountEmail = 'myServiceAccount#appspot.gserviceaccount.com';
// Configuration for the Cloud Task
const task = {
httpRequest: {
httpMethod: 'POST',
url,
oidcToken: {
serviceAccountEmail,
},
body: Buffer.from(JSON.stringify(payload)).toString('base64'),
headers: {
'Content-Type': 'application/json',
},
},
scheduleTime: {
seconds: expirationAtSeconds,
},
};
await tasksClient.createTask({
parent: queuePath,
task,
});
};
export const callbackFn = functions
.region(region)
.https.onRequest(async (req, res) => {
const payload = req.body as ExpirationTaskPayload;
try {
await admin.firestore().doc(payload.docPath).delete();
res.sendStatus(200);
} catch (error) {
console.error(error);
res.status(500).send(error);
}
});
Problem:
The user can also extend the time to live for the document. When that happens the timestamp is successfully updated in the Firestore document, and a http/onUpdate cloud function runs like expected.
Like shown below I tried to update the cloud tasks "time to live", by calling again
the scheduleCloudTask function. Which obviously does not work and I guess just creates another task for the document.
export const onDocTimestampUpdate = functions
.region(region)
.firestore.document('/myCollection/{docId}')
.onUpdate(async (change, context) => {
const before = change.before.data() as ExpirationDocData;
const after = change.after.data() as ExpirationDocData;
if (before.timestamp < after.timestamp) {
const docPath = change.before.ref.path;
await scheduleCloudTask(after.timestamp, docPath)
.then((res) => {
console.log('onUpdate: cloud task created successfully.');
return;
})
.catch((error) => {
console.error(error);
});
} else return;
});
I have not been able to find documentation or examples where an updateTask() or a similar method is used to update an existing task.
Should I use the deleteTask() method and then use the createTask() method and create a new task after the documents timestamp is updated?
Thanks in advance,
Cheers!

Answer 1

Yes, that's how you have to do it. There is no API to update a task.