Why serverless functions matter in GCP - Why It Works

Introduction

Serverless functions let you run small pieces of code without managing servers. They automatically handle scaling and only charge you when your code runs, saving time and money.

When you want to run code in response to events like file uploads or database changes without managing servers.

When you need to quickly deploy small features or APIs without setting up infrastructure.

When your app traffic changes a lot and you want automatic scaling without manual work.

When you want to pay only for the exact time your code runs, not for idle servers.

When you want to focus on writing code and not on server maintenance or updates.

Commands

This command deploys a serverless function named 'helloWorld' using Python 3.9. It triggers on HTTP requests and allows anyone to call it without login.

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

name: projects/PROJECT_ID/locations/REGION/functions/helloWorld

runtime: python39

status: ACTIVE

updateTime: '2024-06-01T12:00:00Z'

→

--runtime - Specifies the language runtime version

→

--trigger-http - Sets the function to run on HTTP requests

→

--allow-unauthenticated - Allows public access without login

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

Terminal

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

Expected Output

Hello, World!

This command fetches the last 5 log entries for the 'helloWorld' function to check its activity and debug if needed.

Terminal

gcloud functions logs read helloWorld --limit 5

Expected Output

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

2024-06-01 12:01:01 helloWorld: Hello, World! response sent

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

→

--limit - Limits the number of log entries returned

Key Concept

If you remember nothing else from this pattern, remember: serverless functions let you run code without managing servers, automatically scaling and charging only when your code runs.

Common Mistakes

Deploying a function without specifying the trigger type

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

Always include a trigger flag like --trigger-http or --trigger-topic when deploying.

Not allowing unauthenticated access when testing public HTTP functions

You will get permission denied errors when trying to call the function publicly.

Use --allow-unauthenticated flag during deployment for public HTTP functions.

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 calling the URL.

Summary

Deploy a serverless function with gcloud specifying runtime and trigger.

Test the function by calling its HTTP URL with curl.

Check function logs to monitor execution and troubleshoot.

Practice

1. What is the main advantage of using serverless functions in cloud computing?

easy

A. You don't have to manage or maintain servers.

B. You get unlimited free storage space.

C. You can run code only on your local machine.

D. You must manually scale the servers.

Solution

1. Step 1: Understand serverless function basics

   Serverless functions let you run code without worrying about the underlying servers.

2. Step 2: Compare options

   Only "You don't have to manage or maintain servers." correctly states that serverless means no server management is needed.

3. Final Answer:

   You don't have to manage or maintain servers. -> Option A

4. Quick Check:

   Serverless means no server management [OK]

Hint: Serverless means no servers to manage [OK]

Common Mistakes:

• Thinking serverless means free unlimited storage
• Believing code runs only locally
• Assuming manual scaling is needed

2. Which of the following is the correct way to define a simple Google Cloud Function in Python?

easy

A. def my_function(): print('Hello World!')

B. def my_function(request): return 'Hello World!'

C. function my_function() { return 'Hello World!'; }

D. my_function = lambda: 'Hello World!'

Solution

1. Step 1: Recall Google Cloud Function Python syntax

   Google Cloud Functions in Python expect a function with a request parameter to handle HTTP events.

2. Step 2: Check options

   def my_function(request): return 'Hello World!' matches the correct signature and returns a response string. Others either lack the request parameter or use wrong syntax.

3. Final Answer:

   def my_function(request): return 'Hello World!' -> Option B

4. Quick Check:

   Python cloud function needs request parameter [OK]

Hint: Python cloud functions need a request parameter [OK]

Common Mistakes:

• Omitting the request parameter in Python function
• Using JavaScript syntax in Python
• Defining functions without return statements

3. Consider this Google Cloud Function code snippet in Python:

def hello_world(request):
    name = request.args.get('name', 'Guest')
    return f'Hello, {name}!'

What will be the response if the function is called with URL parameter ?name=Alice?

medium

A. Hello, Alice!

B. Hello, Guest!

C. Error: missing name parameter

D. Hello, None!

Solution

1. Step 1: Understand request parameter handling

   The function looks for 'name' in the URL parameters and defaults to 'Guest' if not found.

2. Step 2: Analyze given URL parameter

   The URL has '?name=Alice', so the function gets 'Alice' as the name.

3. Final Answer:

   Hello, Alice! -> Option A

4. Quick Check:

   URL param name=Alice returns Hello, Alice! [OK]

Hint: Check URL params; default used only if missing [OK]

Common Mistakes:

• Assuming default is always used
• Expecting an error if parameter is missing
• Confusing None with default value

4. You deployed a Google Cloud Function but it never triggers on HTTP requests. Which of these is the most likely cause?

medium

A. The function is too large in size.

B. The function code has a syntax error.

C. The function was not set to trigger on HTTP events.

D. The function uses an unsupported runtime.

Solution

1. Step 1: Identify trigger configuration importance

   Cloud Functions must be configured with the correct trigger type to respond to events.

2. Step 2: Analyze the problem

   If HTTP requests don't trigger the function, likely the trigger is not set to HTTP.

3. Final Answer:

   The function was not set to trigger on HTTP events. -> Option C

4. Quick Check:

   Trigger type must match event source [OK]

Hint: Check trigger type matches event source [OK]

Common Mistakes:

• Assuming syntax error causes no trigger
• Blaming function size for trigger failure
• Ignoring trigger configuration

5. You want to build a serverless app that processes images uploaded to Cloud Storage and resizes them automatically. Which approach best uses serverless functions to achieve this?

hard

A. Schedule a daily batch job on Compute Engine to resize all images.

B. Run a VM that constantly checks Cloud Storage for new images to resize.

C. Use a Cloud Function triggered by HTTP requests to resize images manually.

D. Deploy a Cloud Function triggered by Cloud Storage upload events to resize images.

Solution

1. Step 1: Identify event-driven serverless use case

   Serverless functions work well when triggered by events like file uploads.

2. Step 2: Match approach to automatic image resizing

   Deploy a Cloud Function triggered by Cloud Storage upload events to resize images uses Cloud Storage upload events to trigger resizing immediately without managing servers.

3. Final Answer:

   Deploy a Cloud Function triggered by Cloud Storage upload events to resize images. -> Option D

4. Quick Check:

   Event-driven serverless = automatic processing [OK]

Hint: Use event triggers for automatic serverless tasks [OK]

Common Mistakes:

• Using VMs instead of serverless for event tasks
• Triggering functions manually via HTTP for automatic jobs
• Scheduling batch jobs instead of event triggers