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.