Cloud Functions

Cloud Functions

Cloud Functions is GCP’s Functions-as-a-Service (FaaS) offering. Write small, focused functions that respond to events — HTTP requests, Pub/Sub messages, Cloud Storage changes, and more.

Cloud Functions vs Cloud Run

Feature	Cloud Functions	Cloud Run
Unit	Function (single handler)	Container (any app)
Runtime	Managed language runtimes	Any container
Max timeout	9 min (HTTP), 10 min (event)	60 min
Cold starts	Higher	Lower with min-instances
Best for	Lightweight event handlers	APIs, web apps

Supported Runtimes

• Node.js 18, 20, 22
• Python 3.9, 3.10, 3.11, 3.12
• Go 1.21, 1.22
• Java 17, 21
• Ruby 3.2
• .NET 6, 8
• PHP 8.2

HTTP Functions

// Node.js HTTP function
const functions = require('@google-cloud/functions-framework');

functions.http('helloWorld', (req, res) => {
  const name = req.query.name || 'World';
  res.send(`Hello, ${name}!`);
});

# Python HTTP function
import functions_framework

@functions_framework.http
def hello_world(request):
    name = request.args.get('name', 'World')
    return f'Hello, {name}!'

Deploying

# Deploy an HTTP function (Node.js)
gcloud functions deploy hello-world \
  --runtime=nodejs20 \
  --trigger-http \
  --entry-point=helloWorld \
  --allow-unauthenticated \
  --region=europe-west2

# Deploy a Python function
gcloud functions deploy hello-world \
  --runtime=python312 \
  --trigger-http \
  --entry-point=hello_world \
  --region=europe-west2

Event-Driven Functions

Pub/Sub Trigger

// Triggered when a message arrives on a Pub/Sub topic
const functions = require('@google-cloud/functions-framework');

functions.cloudEvent('processPubSub', (event) => {
  const message = Buffer.from(event.data.message.data, 'base64').toString();
  console.log('Received:', message);
});

gcloud functions deploy process-pubsub \
  --runtime=nodejs20 \
  --trigger-topic=my-topic \
  --entry-point=processPubSub \
  --region=europe-west2

Cloud Storage Trigger

functions.cloudEvent('onFileUpload', (event) => {
  const file = event.data;
  console.log(`File uploaded: ${file.name} (${file.size} bytes)`);
});

gcloud functions deploy on-file-upload \
  --runtime=nodejs20 \
  --trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
  --trigger-event-filters="bucket=my-bucket-name" \
  --entry-point=onFileUpload \
  --region=europe-west2

Environment Variables and Secrets

# Set environment variables at deploy time
gcloud functions deploy my-function \
  --set-env-vars="DB_HOST=localhost,LOG_LEVEL=info"

# Reference a Secret Manager secret
gcloud functions deploy my-function \
  --set-secrets="API_KEY=my-api-key:latest"

In code:

const apiKey = process.env.API_KEY;

Local Development

# Install the Functions Framework
npm install @google-cloud/functions-framework

# Run locally
npx functions-framework --target=helloWorld
# Visit http://localhost:8080

Scheduling with Cloud Scheduler

Run a Cloud Function on a schedule via Pub/Sub:

# Create a Pub/Sub topic
gcloud pubsub topics create daily-trigger

# Create a Cloud Scheduler job
gcloud scheduler jobs create pubsub daily-cleanup \
  --schedule="0 2 * * *" \
  --topic=daily-trigger \
  --message-body="run"

Useful Commands

# List functions
gcloud functions list

# Describe a function (URL, trigger, config)
gcloud functions describe my-function --region=europe-west2

# View logs
gcloud functions logs read my-function --region=europe-west2

# Call an HTTP function
gcloud functions call my-function \
  --data='{"name":"test"}' \
  --region=europe-west2

# Delete a function
gcloud functions delete my-function --region=europe-west2