Text-to-Voice Tutorial Part 2: Getting Notified When Your Voice File is Ready

This guide covers Part 2 of the text-to-voice workflow: setting up email notifications when your voice file has finished processing and is ready to download.

What you'll build:

A Google Cloud Function that monitors your output bucket
A webhook integration with Make.com (or your preferred automation platform)
An automated email notification with a download link

You will need to have completed:

Part 1 of the text-to-voice tutorial
Google Cloud project with the first function already deployed
Make.com account (free tier works fine)
Input and output Cloud Storage buckets configured

Why This Setup is Necessary

You might wonder why we need this extra complexity—why not just trigger an email when a file lands in the bucket?

The Google Cloud Text-to-Speech API processes long audio files by:

Sending audio in small chunks to your bucket
Creating multiple temporary files
Assembling everything into one complete file at the end

Without the code below, you'd receive an email notification for every temporary file chunk—potentially dozens of spam emails for a single audio file.

The function we're building filters out temporary files and only notifies you when the complete, assembled audio file is ready.

Step 1: Create the Webhook in Make.com

1.1 Set Up the Scenario

Log in to Make.com and create a new scenario
Search for and add a Webhook module
Click Add to create a new webhook
Name it something memorable: Voice File Ready
Copy the webhook URL—you'll need this in Step 2

Leave this browser tab open; we'll come back to complete the email setup later.

Step 2: Create the Google Cloud Function

2.1 Navigate to Cloud Functions

Go back to your Google Cloud Console
Navigate to Cloud Functions (where you created the first function)
Click Create Function

2.2 Configure the Function

Basic Settings:

Function name: voice-file-ready (or your preferred name)
Region: Choose the same region as your storage buckets (critical!)
Runtime: Python 3.x

Trigger Configuration:

Click Add Trigger
Select Cloud Storage
Event type: Finalize/Create
Bucket: Browse and select your OUTPUT bucket (where voice files land)
Click Save

Click Create to proceed to the code editor.

Step 3: Add the Function Code

3.1 Update Entry Point

In the function editor, change the Entry point field to:

notify_audio_ready

3.2 Main Function Code

Replace the contents of main.py with:

import functions_framework
import requests
import json
from datetime import datetime

# --- Configuration ---
# Replace with your own bucket name and webhook URL from Make (or any other automation tool)


OUTPUT_BUCKET = "<your-output-bucket>"   # e.g. "my-voice-files-2"
MAKE_WEBHOOK_URL = "<your-make-webhook>" # e.g. "https://hook.eu1.make.com/bvp1z6pio1..."


@functions_framework.cloud_event
def notify_audio_ready(cloud_event):
    """Triggered when a file is uploaded to the 'voice-out' bucket."""
    data = cloud_event.data
    bucket_name = data.get("bucket")
    object_name = data.get("name")


    print(f"Event: gs://{bucket_name}/{object_name}")


    # Only handle final .wav/.mp3 files in correct bucket
    if bucket_name != OUTPUT_BUCKET:
        print(f"Skipping — wrong bucket: {bucket_name}")
        return
    if not object_name.endswith((".wav", ".mp3")):
        print(f"Skipping — not an audio file: {object_name}")
        return


    # IMPORTANT: Filter out temporary chunk files from Long Audio API
    # These have pattern: filename_{job_id}_{chunk_number}.wav
    # We only want the final assembled file
    parts = object_name.rsplit(".", 1)[0].split("_")
    if len(parts) >= 3 and parts[-1].isdigit() and parts[-2].isdigit():
        print(f"Skipping temporary chunk: {object_name}")
        return


    # Build metadata for Make webhook
    filename = object_name.split("/")[-1]
    gs_uri = f"gs://{bucket_name}/{object_name}"
    public_url = f"https://storage.googleapis.com/{bucket_name}/{object_name}"
    timestamp = datetime.now().isoformat()

    # This next part Builds te metadata for the webhook
    # 
    # You can safely remove any fields you don’t need for your workflow.
    # For most automations, just keeping "public_url" and "message" is enough.
    # Example minimal version:
    # payload = {
    #     "public_url": public_url,
    #     "message": f"🎧 Your audio file '{filename}' is ready!"
    # }
    #


    payload = {
        "event": "audio_file_ready",
        "filename": filename,
        "gs_uri": gs_uri,
        "public_url": public_url,
        "bucket": bucket_name,
        "object_name": object_name,
        "timestamp": timestamp,
        "message": f"🎧 Your audio file '{filename}' is ready for download!"
    }


    try:
        print(f" Sending webhook...")
        response = requests.post(MAKE_WEBHOOK_URL, json=payload, timeout=10)
        response.raise_for_status()
        print(f" Webhook sent! Status: {response.status_code}")
    except requests.RequestException as e:
        print(f" Webhook error: {e}")
        if getattr(e, "response", None):
            print(f"Response text: {e.response.text}")
        raise

‍

3.3 Requirements File

Replace the contents of requirements.txt with:

functions-framework==3.*
requests==2.*

3.4 Make Sure You Configure Your Variables

Before deploying, update these values in the code:

Output Bucket:

OUTPUT_BUCKET = "your-output-bucket-name"

Webhook URL:

MAKE_WEBHOOK_URL = "your-make-webhook-url"

Replace these with:

Your actual output bucket name
The webhook URL you copied from Make.com in Step 1

3.5 Deploy the Function

Click Deploy and wait for the function to build (usually 1-2 minutes).

Step 4: Complete the Email Setup in Make.com

4.1 Set Up Data Structure

Go back to your Make.com scenario
Click on the webhook module
Click Redetermine data structure
The webhook is now listening...

4.2 Trigger a Test

To populate the data structure:

Go to your Google Cloud Storage input bucket
Upload a test text file (any small .txt or .md file)
This triggers the full workflow

Within a few seconds, Make.com should receive the webhook data and you'll see "Successfully determined" in the webhook module.

4.3 Add Gmail Module

Click the + button after the webhook
Search for and add Gmail > Send an Email
Create a connection to your Gmail account (follow the authentication prompts)
Configure the email:

To: Your email address

Subject: Voice File Ready (or your preferred subject)

Message example:

Your voice file is ready!<br/><br/>

Download here: [map: public_url from webhook]

‍

To add the download link:

Click in the Message field
Find public_url in the webhook data
Click to insert it

You can use any of these fields in your automation. The example above uses public_url to provide a direct download link, but you could also:

Use file_name in the email subject
Store bucket_name for record keeping
Trigger different actions based on event_type

‍

4.4 Test the Complete Workflow

Save the scenario in Make.com
Turn on the scenario (toggle in the bottom left)
Upload another test file to your input bucket
Wait 30-60 seconds
Check your email—you should receive the notification with a clickable download link

‍

Understanding What Gets Sent to the Webhook

The Cloud Function sends structured data to your webhook that you can use in your automations. Here's what a real webhook payload looks like:

event: audio_file_ready
filename: simple-test_14-10-2025.wav
gs_uri: gs://my-voice-2/simple-test_14-10-2025.wav
public_url: https://storage.googleapis.com/my-voi-iles-2/simple_14-10-2025.wav
bucket: my-voice-files-2
object_name: simple-test_14-10-2025.wav
timestamp: 2025-10-14T15:54:09.108763
message: 🎧 Your audio file 'simple-test_14-10-2025.wav' is ready for download!

‍

Field Descriptions

event - Event type identifier (useful if you're handling multiple event types)
filename - Just the filename without path
gs_uri - Google Storage URI (for programmatic access)
public_url - Direct download link (this is what you want for emails!)
bucket - Name of the output bucket
object_name - Full object name/path in bucket
timestamp - When the file was created
message - Ready-to-use notification message with emoji

Customising the Webhook Payload

You can customise what data gets sent by modifying the function code. The payload is built in the main.py section shown below:

python

# This next part builds the metadata for the webhook
# ------------------------------------------------------------
# You can safely remove any fields you don't need for your workflow.
# For most automations, just keeping "public_url" and "message" is enough.
# Example minimal version:
# payload = {
#     "public_url": public_url,
#     "message": f"🎧 Your audio file '{filename}' is ready!"
# }
# ------------------------------------------------------------
payload = {
    "event": "audio_file_ready",
    "filename": filename,
    "gs_uri": gs_uri,
    "public_url": public_url,
    "bucket": bucket_name,
    "object_name": object_name,
    "timestamp": timestamp,
    "message": f"🎧 Your audio file '{filename}' is ready for download!"
}

Common Use Cases

Simple email notification: Just use public_url and message

Advanced workflows: Use all fields to:

Store gs_uri in a database for record keeping
Use timestamp to track processing times
Filter by event type if handling multiple notification types
Use bucket and object_name for additional file operations
Include filename in email subjects or logging

Troubleshooting

Not Receiving Emails?

Check Make.com scenario is running (toggle should be blue/on)
Verify webhook received data (click on webhook module to see execution history)
Check spam folder for the email
Verify Gmail connection is still authenticated in Make.com

Remember: The most common issues are mismatched bucket names or regions, and authentication problems with Make.com or Gmail.

Alternative Automation Platforms

Whilst this guide uses Make.com, the same approach works with:

Zapier - Use "Webhooks by Zapier" with "Catch Hook"
n8n - Use the Webhook node
Any platform with webhook support

Simply replace the Make.com webhook URL with your platform's webhook URL in the function code.