Create and deploy a HTTP Cloud Function by using Python

This guide takes you through the process of writing a Cloud Function using the Python runtime. There are two types of Cloud Functions:

An HTTP function, which you invoke from standard HTTP requests.
An event-driven function, which you use to handle events from your Cloud infrastructure, such as messages on a Cloud Pub/Sub topic, or changes in a Cloud Storage bucket.

The sample shows how to create a simple HTTP function.

Guide structure

Creating a GCP project using gcloud CLI

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Cloud project. Learn how to check if billing is enabled on a project.

Enable the Cloud Functions and Cloud Build APIs.

Enable the APIs

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Cloud project. Learn how to check if billing is enabled on a project.

Enable the Cloud Functions and Cloud Build APIs.

Enable the APIs

Install and initialize the gcloud CLI.
Update and install gcloud components:
```
gcloud components update
```

Prepare your development environment.
Go to the Python setup guide

Creating a function

Create a directory on your local system for the function code:

Linux or Mac OS X

mkdir ~/helloworld
cd ~/helloworld

Windows

mkdir %HOMEPATH%\helloworld
cd %HOMEPATH%\helloworld

Create a main.py file in the helloworld directory with the following contents:

functions/helloworld/main.py

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from flask import escape
import functions_framework

@functions_framework.http
def hello_http(request):
    """HTTP Cloud Function.
    Args:
        request (flask.Request): The request object.
        <https://flask.palletsprojects.com/en/1.1.x/api/#incoming-request-data>
    Returns:
        The response text, or any set of values that can be turned into a
        Response object using `make_response`
        <https://flask.palletsprojects.com/en/1.1.x/api/#flask.make_response>.
    """
    request_json = request.get_json(silent=True)
    request_args = request.args

    if request_json and 'name' in request_json:
        name = request_json['name']
    elif request_args and 'name' in request_args:
        name = request_args['name']
    else:
        name = 'World'
    return 'Hello {}!'.format(escape(name))

This example function takes a name supplied in the HTTP request and returns a greeting, or "Hello World!" when no name is supplied.

Specifying dependencies

Dependencies in Python are managed with pip and expressed in a metadata file called requirements.txt. This file must be in the same directory as the main.py file that contains your function code.

You don't need to create a requirements.txt to run this particular sample, but suppose you wanted to add your own dependencies. Here's how you would do it:

Create a requirements.txt file in the helloworld directory.

Add the function's dependency, to your requirements.txt file, for example:

# An example requirements file, add your dependencies below
sampleproject==2.0.0

Deploying the function

To deploy the function with an HTTP trigger, run the following command in the helloworld directory:

gcloud functions deploy hello_http --runtime python311 --trigger-http --allow-unauthenticated

The --allow-unauthenticated flag lets you reach the function without authentication. To require authentication, omit the flag.

Testing the function

When the function finishes deploying, take note of the httpsTrigger.url property or find it using the following command:
```
gcloud functions describe hello_http
```
It should look like this:
```
https://GCP_REGION-PROJECT_ID.cloudfunctions.net/hello_http
```
Visit this URL in your browser. You should see a "Hello World!" message.

Try passing a name in the HTTP request, for example by using the following URL:
```
https://GCP_REGION-PROJECT_ID.cloudfunctions.net/hello_http?name=NAME
```
You should see the message "Hello NAME!"

Viewing logs

Using the command-line tool

Logs for Cloud Functions are viewable in the Cloud Logging UI, and via the Google Cloud CLI.

To view logs for your function with the gcloud CLI, use the logs read command, followed by the name of the function:

gcloud functions logs read hello_http

The output should resemble the following:

LEVEL  NAME        EXECUTION_ID  TIME_UTC                 LOG
D      hello_http  pdb5ys2t022n  2019-09-18 23:29:09.791  Function execution started
D      hello_http  pdb5ys2t022n  2019-09-18 23:29:09.798  Function execution took 7 ms, finished with status code: 200

Using the Logging dashboard

You can also view logs for Cloud Functions from the Google Cloud console.