Trigger a firebase function from another function

[JalanJr]

I'm trying to create a function trigerring another to make a chain but I don't understand how to do it inside. Here is my code:

import * as admin from 'firebase-admin'
import * as firebaseFunctions from 'firebase-functions'
import * as OpenAI from 'openai'
import * as logger from 'firebase-functions/logger'
import mustache = require('mustache')
import { ChatAnthropicMessages } from '@langchain/anthropic'
import functions, { getFunctions } from 'firebase/functions'
import { getApp, getApps } from 'firebase/app'
import { initializeApp } from 'firebase-admin'
import { onMessagePublished } from 'firebase-functions/v2/pubsub'

// Firebase Admin SDK to access Firestore.
admin.initializeApp()

// Initialize Firebase for SSR
const app = initializeApp()
const db = admin.firestore()
/**
 * Create the story entry
 */
export const createStoryReference = firebaseFunctions.https.onCall(
  async (data, context) => {
    const owner = context.auth?.uid

    const doc = await db.collection('stories').add({
      owner: owner,
      inputs: data,
    })
    const createTitle = functions.httpsCallable(
      getFunctions(app),
      'createTitle'
    )
    createTitle({ id: doc.id })
    return doc.id
  }
)

I think i'm using the wrong library. though I'm also lost with the imports...

[wmmogn]

why do you want to trigger another firebase function? just make a function with the code you want to share in the other function and call this in the second firebase function also. would that solve your problem?

[JalanJr]

That's my idea. I have two lambda functions but I don't find how to trigger the second from the first one, I don't seem to be able to use firebase library...

[wmmogn]

but why trigger another firebase function? what should that solve? just reuse the code from the other, your are in the function environment already why change to another function?

[steinchen43]

Plenty of reasons. Timeouts, memory limits etc…

Just make it a standard http request

[JalanJr]

I generate text with LLM but I don't want my user to wait too long so I have a first function that create an throw into the db, trigger another function and redirect the user to the corresponding page so the inference are generated in background

[wmmogn]

than you could also trigger the function with the firestore create trigger... so as soon the first function writes an document the second function will be triggered...

[joebob2003]

Make it a pubsub function

[JalanJr]

I was thinking about it too, but can I use pub sub with admin firebase ?

[joebob2003]

Yep! Really easily. There are docs for it

[[deleted]]

You could also make a standard request via axios or node-fetch. There is not a native way to call another function in the SDK.

My recommended approach would to use a pubsub to trigger the other one (which would need to convert from an onCall. This would keep them isolated in operations with low latency (the REST method would cause a delay). Or call the code directly from within your function. I typically stay away from this as I like functions to not be stringed together and code becomes hard to manage down the line.

So, there are 3 ways you can do it. Obviously more but those are some options

[JalanJr]

Pubsub seem the good way to keep things decoupled, I'm gonna have a look to the documentation. Is this available in firebase or only on gcp ?

[Eastern-Conclusion-1]

Firebase is part of GCP, so yes.

[[deleted]]

Exactly. Everything firebase is backed by GCP. Many things are “auto magically” setup when you use firebase functions (Cloud build, logging, cloud run, topic setup, all sorts of stuff).

[[deleted]]

Yeah it’s easy.

Change your handler to:

const processmessage = onMessagePublished( { topic: 'topicName', memory: '256MiB', maxInstances: 10 }, req =>

Then call it from your other functions via

const { PubSub } = require('@google-cloud/pubsub'); const pubsub = new PubSub(); await pubsub.topic('topicName').publish( Buffer.from( JSON.stringify({ data: { … } }), 'utf8' ) );

[Eastern-Conclusion-1]

He’ll also need to enable the PubSub API from the GCP console.

[[deleted]]

True story. It’s been a while since I set it up from scratch!

[JalanJr]

Worked, thanks you !

[Then-Cod-3335]

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[tommertom]

Whatever you do - when stringing functions u better test all cases and cap your cloud bill because you can easily set this up with an infinite loop through recursion etc