Why serverless patterns matter in GCP - Why It Works

Introduction

Serverless patterns help you build apps without managing servers. They let you focus on your code while the cloud handles running and scaling it automatically.

When you want to run code that reacts to events like file uploads or messages without setting up servers.

When you need your app to handle sudden traffic spikes without manual scaling.

When you want to pay only for the exact time your code runs, saving money.

When you want to build small, independent functions that do one job well.

When you want to avoid the hassle of patching and maintaining servers.

Commands

This command deploys a serverless function named helloWorld using Python 3.9. It triggers on HTTP requests and allows anyone to call it.

Terminal

gcloud functions deploy helloWorld --runtime python39 --trigger-http --allow-unauthenticated

Expected Output

Deploying function (may take a while)...done.

availableMemoryMb: 256

entryPoint: helloWorld

httpsTrigger:

  url: https://REGION-PROJECT_ID.cloudfunctions.net/helloWorld

runtime: python39

status: ACTIVE

→

--runtime - Specifies the programming language and version for the function.

→

--trigger-http - Sets the function to run when it receives an HTTP request.

→

--allow-unauthenticated - Allows anyone to call the function without login.

This command calls the deployed serverless function via its HTTP URL to test it works.

Terminal

curl https://REGION-PROJECT_ID.cloudfunctions.net/helloWorld

Expected Output

Hello, World!

This command fetches the last 5 log entries from the helloWorld function to check its behavior and troubleshoot if needed.

Terminal

gcloud functions logs read helloWorld --limit 5

Expected Output

2024-06-01 12:00:00 helloWorld: Function execution started

2024-06-01 12:00:01 helloWorld: Hello, World!

2024-06-01 12:00:01 helloWorld: Function execution finished

→

--limit - Limits the number of log entries shown.

Key Concept

If you remember nothing else from this pattern, remember: serverless lets you run code without managing servers, automatically scaling and charging only for what you use.

Common Mistakes

Not specifying the trigger type when deploying the function.

The function won't know when to run and deployment will fail or the function won't respond.

Always include a trigger flag like --trigger-http or --trigger-topic to define how the function is invoked.

Forgetting to allow unauthenticated access for public HTTP functions.

The function will reject calls from users who are not logged in, causing errors.

Add --allow-unauthenticated flag if you want anyone to access the function.

Calling the function URL before deployment finishes.

The function won't respond because it is not ready yet.

Wait for the deployment command to complete successfully before testing the function.

Summary

Deploy a serverless function with gcloud specifying runtime and trigger.

Test the function by calling its HTTP URL.

Check function logs to monitor and troubleshoot behavior.

Practice

1. What is the main benefit of using serverless patterns in cloud applications?

easy

A. Fixed monthly billing regardless of usage

B. Manual control over server hardware

C. Automatic scaling without managing servers

D. Requires setting up virtual machines

Solution

1. Step 1: Understand serverless basics

   Serverless means the cloud provider manages servers, so you don't have to.

2. Step 2: Identify key benefit

   Serverless apps scale automatically based on demand without manual server management.

3. Final Answer:

   Automatic scaling without managing servers -> Option C

4. Quick Check:

   Serverless = automatic scaling [OK]

Hint: Serverless means no server setup needed [OK]

Common Mistakes:

• Thinking serverless means no servers exist
• Assuming fixed billing regardless of usage
• Confusing serverless with manual server control

2. Which of the following is the correct way to define a Cloud Function trigger in GCP serverless pattern?

easy

A. trigger: http

B. trigger: virtual_machine

C. trigger: manual_start

D. trigger: database_backup

Solution

1. Step 1: Recall Cloud Function triggers

   Cloud Functions commonly trigger on HTTP requests or events, not manual or VM triggers.

2. Step 2: Identify valid trigger

   trigger: http is the correct syntax for HTTP-triggered functions.

3. Final Answer:

   <code>trigger: http</code> -> Option A

4. Quick Check:

   HTTP trigger syntax = correct [OK]

Hint: Cloud Functions trigger on events like HTTP [OK]

Common Mistakes:

• Using triggers that don't exist like manual_start
• Confusing VM triggers with serverless triggers
• Assuming database_backup is a trigger

3. Given this serverless function code snippet in GCP:

def hello_world(event, context):
    print('Hello, world!')

What happens when this function is deployed and triggered by an event?

medium

A. The function prints 'Hello, world!' to the logs

B. The function returns 'Hello, world!' to the caller

C. The function fails because of missing return statement

D. The function runs only once and then stops

Solution

1. Step 1: Understand function behavior

   The function prints a message to logs when triggered; no return value is needed.

2. Step 2: Identify output

   Print statements appear in logs, not as return to caller.

3. Final Answer:

   The function prints 'Hello, world!' to the logs -> Option A

4. Quick Check:

   Print output = logs [OK]

Hint: Print outputs go to logs, not caller [OK]

Common Mistakes:

• Expecting print to return value to caller
• Thinking missing return causes failure
• Assuming function runs only once

4. You deployed a serverless function but it never triggers on new file uploads to Cloud Storage. What is the most likely cause?

medium

A. The function code has syntax errors

B. The function trigger is not set to Cloud Storage events

C. The Cloud Storage bucket is empty

D. The function is set to manual trigger only

Solution

1. Step 1: Check trigger configuration

   For automatic runs on file uploads, the function must have a Cloud Storage event trigger.

2. Step 2: Identify cause of no trigger

   If trigger is missing or incorrect, function won't run on uploads.

3. Final Answer:

   The function trigger is not set to Cloud Storage events -> Option B

4. Quick Check:

   Trigger mismatch = no function run [OK]

Hint: Check event trigger matches source action [OK]

Common Mistakes:

• Assuming empty bucket stops triggers
• Blaming code errors without checking triggers
• Confusing manual trigger with event trigger

5. You want to build a serverless app that processes images uploaded to Cloud Storage and stores metadata in Firestore. Which serverless pattern best fits this use case?

hard

A. Using a scheduled job to scan the bucket every hour

B. Manual invocation of functions via HTTP requests

C. Running a VM continuously to watch the bucket

D. Event-driven functions triggered by Cloud Storage events

Solution

1. Step 1: Analyze use case requirements

   The app needs to react immediately to image uploads and process them.

2. Step 2: Match pattern to requirement

   Event-driven functions triggered by Cloud Storage events run code automatically on uploads.

3. Step 3: Evaluate other options

   Manual HTTP triggers, VMs, or scheduled jobs are less efficient or not real-time.

4. Final Answer:

   Event-driven functions triggered by Cloud Storage events -> Option D

5. Quick Check:

   Event-driven = automatic, real-time processing [OK]

Hint: Use event triggers for real-time processing [OK]

Common Mistakes:

• Choosing manual triggers for automatic events
• Using VMs instead of serverless functions
• Relying on scheduled jobs for immediate processing