Function deployment and testing in GCP - Commands & Configuration

Introduction

Deploying a function means putting your code into the cloud so it can run when needed. Testing the function ensures it works correctly after deployment.

When you want to run small pieces of code in response to events without managing servers

When you need to quickly update your code and see the changes live

When you want to test if your cloud function responds correctly to HTTP requests

When you want to automate tasks triggered by cloud storage or messaging events

When you want to save costs by running code only when it is needed

Config File - main.py

main.py

def hello_world(request):
    return 'Hello, World!'

This is a simple Python function named hello_world that returns a greeting message. It accepts a request object because it will be triggered by HTTP requests.

Commands

This command deploys the function named 'hello_world' using Python 3.9 runtime. It sets the function to trigger on HTTP requests and allows anyone to call it. The region is set to us-central1.

Terminal

gcloud functions deploy hello_world --runtime python39 --trigger-http --allow-unauthenticated --region us-central1

Expected Output

Deploying function (may take a while)...

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

availableMemoryMb: 256

entryPoint: hello_world

httpsTrigger:

  url: https://us-central1-your-project.cloudfunctions.net/hello_world

ingressSettings: ALLOW_ALL

labels:

  deployment-tool: cli-gcloud

name: projects/your-project/locations/us-central1/functions/hello_world

runtime: python39

serviceAccountEmail: [e-mail]

sourceUploadUrl: https://storage.googleapis.com/gcf-upload-us-central1/...

status: ACTIVE

timeout: 60s

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

versionId: '1'

→

--runtime - Specifies the language runtime version

→

--trigger-http - Sets the function to be triggered by HTTP requests

→

--allow-unauthenticated - Allows public access to the function

This command calls the deployed function 'hello_world' to test if it responds correctly.

Terminal

gcloud functions call hello_world --region us-central1

Expected Output

executionId: abcdef123456

result: Hello, World!

→

--region - Specifies the region where the function is deployed

This command sends an HTTP GET request to the function's URL to test it from outside the cloud console.

Terminal

curl https://us-central1-your-project.cloudfunctions.net/hello_world

Expected Output

Hello, World!

Key Concept

If you remember nothing else from this pattern, remember: deploy your function with the right trigger and test it immediately to confirm it works.

Common Mistakes

Forgetting to add --allow-unauthenticated flag when deploying HTTP functions

The function will reject public requests and appear unreachable

Always include --allow-unauthenticated if you want public access or configure IAM permissions properly

Calling the function without specifying the correct region

The call will fail because the CLI looks in the wrong location

Use --region flag matching the deployment region when calling the function

Not testing the function after deployment

You might miss errors or misconfigurations that prevent the function from working

Always run a test call or HTTP request to verify the function works as expected

Summary

Deploy the function with gcloud specifying runtime, trigger, and access flags.

Test the function using gcloud call command to check the response.

Use curl to send HTTP requests and verify the function works from outside the cloud console.