Cloud Functions: Qwik Start - Command Line

Join Sign in

Cloud Functions: Qwik Start - Command Line

30 minutes 1 Credit


Google Cloud self-paced labs logo


Cloud Functions is a serverless execution environment for building and connecting cloud services. With Cloud Functions you write simple, single-purpose functions that are attached to events emitted from your cloud infrastructure and services. Your Cloud Function is triggered when an event being watched is fired. Your code executes in a fully managed environment. There is no need to provision any infrastructure or worry about managing any servers.

Cloud Functions can be written in Node.js, Python, and Go, and are executed in language-specific runtimes as well. You can take your Cloud Function and run it in any standard Node.js runtime which makes both portability and local testing a breeze.

Connect and extend Cloud Services

Cloud Functions provides a connective layer of logic that lets you write code to connect and extend cloud services. Listen and respond to a file upload to Cloud Storage, a log change, or an incoming message on a Cloud Pub/Sub topic.

Cloud Functions augments existing cloud services and allows you to address an increasing number of use cases with arbitrary programming logic.

Cloud Functions have access to the Google Service Account credential and are thus seamlessly authenticated with the majority of Google Cloud services such as Datastore, Cloud Spanner, Cloud Translation API, Cloud Vision API, as well as many others. In addition, Cloud Functions are supported by numerous Node.js client libraries, which further simplify these integrations.

Events and triggers

Cloud events are things that happen in your cloud environment.These might be things like changes to data in a database, files added to a storage system, or a new virtual machine instance being created.

Events occur whether or not you choose to respond to them. You create a response to an event with a trigger. A trigger is a declaration that you are interested in a certain event or set of events. Binding a function to a trigger allows you to capture and act on events. For more information on creating triggers and associating them with your functions, see the Events and Triggers section of the Cloud Functions Guides.


Cloud Functions removes the work of managing servers, configuring software, updating frameworks, and patching operating systems. The software and infrastructure are fully managed by Google so that you just add code. Furthermore, provisioning of resources happens automatically in response to events. This means that a function can scale from a few invocations a day to many millions of invocations without any work from you.

Use cases

Asynchronous workloads, for example lightweight ETL or cloud automations, like triggering application builds, no longer need their own server and a developer to wire it up. You simply deploy a Cloud Function bound to the event you want and you're done.

The fine-grained, on-demand nature of Cloud Functions also makes it a perfect candidate for lightweight APIs and webhooks. Because there is automatic provisioning of HTTP endpoints when you deploy an HTTP Function, there is no complicated configuration required as there is with some other services. See the following table for additional common Cloud Functions use cases:

Use Case


Data Processing / ETL

Listen and respond to Cloud Storage events such as when a file is created, changed, or removed. Process images, perform video transcoding, validate and transform data, and invoke any service on the Internet from your Cloud Function.


Via a simple HTTP trigger, respond to events originating from 3rd party systems like GitHub, Slack, Stripe, or from anywhere that can send HTTP requests.

Lightweight APIs

Compose applications from lightweight, loosely coupled bits of logic that are quick to build and that scale instantly. Your functions can be event-driven or invoked directly over HTTP/S.

Mobile Backend

Use Google's mobile platform for app developers, Firebase, and write your mobile backend in Cloud Functions. Listen and respond to events from Firebase Analytics, Realtime Database, Authentication, and Storage.


Imagine tens or hundreds of thousands of devices streaming data into Cloud Pub/Sub, thereby launching Cloud Functions to process, transform and store data. Cloud Functions lets you do things in a way that's completely serverless.

This hands-on lab shows you how to create, deploy, and test a cloud function using the Google Cloud Shell command line.

What you'll do

  • Create a simple cloud function
  • Deploy and test the function
  • View logs


Before you click the Start Lab button

Read these instructions. Labs are timed and you cannot pause them. The timer, which starts when you click Start Lab, shows how long Google Cloud resources will be made available to you.

This hands-on lab lets you do the lab activities yourself in a real cloud environment, not in a simulation or demo environment. It does so by giving you new, temporary credentials that you use to sign in and access Google Cloud for the duration of the lab.

To complete this lab, you need:

  • Access to a standard internet browser (Chrome browser recommended).
Note: Use an Incognito or private browser window to run this lab. This prevents any conflicts between your personal account and the Student account, which may cause extra charges incurred to your personal account.
  • Time to complete the lab---remember, once you start, you cannot pause a lab.
Note: If you already have your own personal Google Cloud account or project, do not use it for this lab to avoid extra charges to your account.

How to start your lab and sign in to the Google Cloud Console

  1. Click the Start Lab button. If you need to pay for the lab, a pop-up opens for you to select your payment method. On the left is the Lab Details panel with the following:

    • The Open Google Console button
    • Time remaining
    • The temporary credentials that you must use for this lab
    • Other information, if needed, to step through this lab
  2. Click Open Google Console. The lab spins up resources, and then opens another tab that shows the Sign in page.

    Tip: Arrange the tabs in separate windows, side-by-side.

    Note: If you see the Choose an account dialog, click Use Another Account.
  3. If necessary, copy the Username from the Lab Details panel and paste it into the Sign in dialog. Click Next.

  4. Copy the Password from the Lab Details panel and paste it into the Welcome dialog. Click Next.

    Important: You must use the credentials from the left panel. Do not use your Google Cloud Skills Boost credentials. Note: Using your own Google Cloud account for this lab may incur extra charges.
  5. Click through the subsequent pages:

    • Accept the terms and conditions.
    • Do not add recovery options or two-factor authentication (because this is a temporary account).
    • Do not sign up for free trials.

After a few moments, the Cloud Console opens in this tab.

Note: You can view the menu with a list of Google Cloud Products and Services by clicking the Navigation menu at the top-left. Navigation menu icon

Activate Cloud Shell

Cloud Shell is a virtual machine that is loaded with development tools. It offers a persistent 5GB home directory and runs on the Google Cloud. Cloud Shell provides command-line access to your Google Cloud resources.

  1. Click Activate Cloud Shell Activate Cloud Shell icon at the top of the Google Cloud console.

When you are connected, you are already authenticated, and the project is set to your PROJECT_ID. The output contains a line that declares the PROJECT_ID for this session:

Your Cloud Platform project in this session is set to YOUR_PROJECT_ID

gcloud is the command-line tool for Google Cloud. It comes pre-installed on Cloud Shell and supports tab-completion.

  1. (Optional) You can list the active account name with this command:

gcloud auth list
  1. Click Authorize.

  2. Your output should now look like this:


ACTIVE: * ACCOUNT: To set the active account, run: $ gcloud config set account `ACCOUNT`
  1. (Optional) You can list the project ID with this command:

gcloud config list project


[core] project = <project_ID>

Example output:

[core] project = qwiklabs-gcp-44776a13dea667a6 Note: For full documentation of gcloud, in Google Cloud, refer to the gcloud CLI overview guide.

Task 1. Create a function

First, you're going to create a simple function named helloWorld. This function writes a message to the Cloud Functions logs. It is triggered by cloud function events and accepts a callback function used to signal completion of the function.

For this lab the cloud function event is a cloud pub/sub topic event. A pub/sub is a messaging service where the senders of messages are decoupled from the receivers of messages. When a message is sent or posted, a subscription is required for a receiver to be alerted and receive the message. To learn more about pub/subs, in Cloud Pub/Sub Guides, see Google Cloud Pub/Sub: A Google-Scale Messaging Service.

To learn more about the event parameter and the callback parameter, in Cloud Functions Documentation, see Background Functions.

To create a cloud function:

  1. In the Cloud Shell command line, create a directory for the function code:

    mkdir gcf_hello_world
  2. Move to the gcf_hello_world directory:

    cd gcf_hello_world
  3. Create and open index.js to edit:

    nano index.js
  4. Copy the following into the index.js file:

    /** * Background Cloud Function to be triggered by Pub/Sub. * This function is exported by index.js, and executed when * the trigger topic receives a message. * * @param {object} data The event payload. * @param {object} context The event metadata. */ exports.helloWorld = (data, context) => { const pubSubMessage = data; const name = ? Buffer.from(, 'base64').toString() : "Hello World"; console.log(`My Cloud Function: ${name}`); };
  5. Exit nano (Ctrl+x) and save (Y) the file.

Task 2. Create a cloud storage bucket

  • Use the following command to create a new cloud storage bucket for your function:

gsutil mb -p [PROJECT_ID] gs://[BUCKET_NAME]
  • PROJECT_ID is the Project ID in the lab details panel on the left of this lab

  • BUCKET_NAME is the name you give to the bucket. It must be a globally unique name. To learn more about naming buckets, In Cloud Storage Documentation, see Bucket naming guidelines.

Test Completed Task

Click Check my progress to verify your performed task. If you have completed the task successfully you will be granted with an assessment score.

Create a cloud storage bucket.

Task 3. Deploy your function

When deploying a new function, you must specify --trigger-topic, --trigger-bucket, or --trigger-http. When deploying an update to an existing function, the function keeps the existing trigger unless otherwise specified.

For this lab, you'll set the --trigger-topic as hello_world.

  1. Deploy the function to a pub/sub topic named hello_world, replacing [BUCKET_NAME] with the name of your bucket:

    gcloud functions deploy helloWorld \ --stage-bucket [BUCKET_NAME] \ --trigger-topic hello_world \ --runtime nodejs8 Note: If you get OperationError, ignore the warning and re-run the command.

If prompted, enter Y to allow unauthenticated invocations of a new function.

  1. Verify the status of the function:

    gcloud functions describe helloWorld

An ACTIVE status indicates that the function has been deployed.

entryPoint: helloWorld eventTrigger: eventType: providers/cloud.pubsub/eventTypes/topic.publish failurePolicy: {} resource: ... status: ACTIVE ...

Every message published in the topic triggers function execution, the message contents are passed as input data.

Test Completed Task

Click Check my progress to verify your performed task. If you have completed the task successfully you will receive an assessment score.

Deploy the function.

Task 4. Test the function

After you deploy the function and know that it's active, test that the function writes a message to the cloud log after detecting an event.

  • Enter this command to create a message test of the function:

DATA=$(printf 'Hello World!'|base64) && gcloud functions call helloWorld --data '{"data":"'$DATA'"}'

The cloud tool returns the execution ID for the function, which means a message has been written in the log.

Example output:

executionId: 3zmhpf7l6j5b

View logs to confirm that there are log messages with that execution ID.

Task 5. View logs

  • Check the logs to see your messages in the log history:

gcloud functions logs read helloWorld

If the function executed successfully, messages in the log appear as follows:

LEVEL NAME EXECUTION_ID TIME_UTC LOG D helloWorld 3zmhpf7l6j5b 2017-12-05 22:17:42.585 Function execution started I helloWorld 3zmhpf7l6j5b 2017-12-05 22:17:42.650 My Cloud Function: Hello World! D helloWorld 3zmhpf7l6j5b 2017-12-05 22:17:42.666 Function execution took 81 ms, finished with status: 'ok' Note: The logs will take around 10 mins to appear. Also, the alternative way to view the logs is, go to Logging > Logs Explorer.

Your application is deployed, tested, and you can view the logs.

Task 6. Test your understanding

Below are multiple-choice questions to reinforce your understanding of this lab's concepts. Answer them to the best of your abilities.


Finish your quest

This self-paced lab is part of the Baseline: Deploy & Develop, Baseline: Infrastructure, and Optimizing your Google Cloud Costs quests. A quest is a series of related labs that form a learning path. Completing this quest earns you a badge to recognize your achievement. You can make your badge or badges public and link to them in your online resume or social media account. Enroll in any quest that contains this lab and get immediate completion credit. See the Google Cloud Skills Boost catalog to see all available quests.

Take your next lab

This lab is also part of a series of labs called Qwik Starts. These labs are designed to give you a little taste of the many features available with Google Cloud. Search for "Qwik Starts" in the lab catalog to find the next lab you'd like to take!

Next steps / Learn more

Google Cloud training and certification

...helps you make the most of Google Cloud technologies. Our classes include technical skills and best practices to help you get up to speed quickly and continue your learning journey. We offer fundamental to advanced level training, with on-demand, live, and virtual options to suit your busy schedule. Certifications help you validate and prove your skill and expertise in Google Cloud technologies.

Manual Last Updated June 26, 2022

Lab Last Tested January 8, 2021

Copyright 2023 Google LLC All rights reserved. Google and the Google logo are trademarks of Google LLC. All other company and product names may be trademarks of the respective companies with which they are associated.