HTTP Tutorial

This simple tutorial demonstrates writing, deploying, and triggering an HTTP Cloud Function.

Objectives

• Write, deploy, and trigger an HTTP Cloud Function.

Costs

This tutorial uses billable components of Cloud Platform, including:

• Google Cloud Functions

Use the Pricing Calculator to generate a cost estimate based on your projected usage.

Before you begin

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. In the Cloud Console, on the project selector page, select or create a Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to the project selector page

3. Make sure that billing is enabled for your Google Cloud project. Learn how to confirm billing is enabled for your project.

4. Enable the Cloud Functions and Cloud Build APIs.

   Enable the APIs

5. Update gcloud components:

   gcloud components update

6. Prepare your development environment.

   Node.js

   Go to the Node.js setup guide

   Python

   Go to the Python setup guide

   Go

   Go to the Go setup guide

   Java

   Go to the Java setup guide

Preparing the application

1. Clone the sample app repository to your local machine:

   Node.js

   git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git

   Alternatively, you can download the sample as a zip file and extract it.

   Python

   git clone https://github.com/GoogleCloudPlatform/python-docs-samples.git

   Alternatively, you can download the sample as a zip file and extract it.

   Go

   git clone https://github.com/GoogleCloudPlatform/golang-samples.git

   Alternatively, you can download the sample as a zip file and extract it.

   Java

   git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git

   Alternatively, you can download the sample as a zip file and extract it.

2. Change to the directory that contains the Cloud Functions sample code:

   Node.js

   cd nodejs-docs-samples/functions/helloworld/

   Python

   cd python-docs-samples/functions/helloworld/

   Go

   cd golang-samples/functions/helloworld/

   Java

   cd java-docs-samples/functions/helloworld/helloworld/

3. Take a look at the sample code:

   Node.js

   functions/helloworld/index.js

   View on GitHub

   /**
    * HTTP Cloud Function.
    * This function is exported by index.js, and is executed when
    * you make an HTTP request to the deployed function's endpoint.
    *
    * @param {Object} req Cloud Function request context.
    *                     More info: https://expressjs.com/en/api.html#req
    * @param {Object} res Cloud Function response context.
    *                     More info: https://expressjs.com/en/api.html#res
    */
   exports.helloGET = (req, res) => {
     res.send('Hello World!');
   };

   Python

   functions/helloworld/main.py

   View on GitHub

   def hello_get(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>.
       """
       return 'Hello World!'

   Go

   functions/helloworld/hello_world.go

   View on GitHub

   
   // Package helloworld provides a set of Cloud Functions samples.
   package helloworld
   
   import (
   	"fmt"
   	"net/http"
   )
   
   // HelloGet is an HTTP Cloud Function.
   func HelloGet(w http.ResponseWriter, r *http.Request) {
   	fmt.Fprint(w, "Hello, World!")
   }
   

   Java

   functions/helloworld/helloworld/src/main/java/functions/HelloWorld.java

   View on GitHub

   
   package functions;
   
   import com.google.cloud.functions.HttpFunction;
   import com.google.cloud.functions.HttpRequest;
   import com.google.cloud.functions.HttpResponse;
   import java.io.BufferedWriter;
   import java.io.IOException;
   
   public class HelloWorld implements HttpFunction {
     // Simple function to return "Hello World"
     @Override
     public void service(HttpRequest request, HttpResponse response)
         throws IOException {
       BufferedWriter writer = response.getWriter();
       writer.write("Hello World!");
     }
   }

Deploying the function

To deploy the function with an HTTP trigger, run the following command in the directory that contains the sample code (or in the case of Java, the pom.xml file):

Node.js

gcloud functions deploy helloGET \
--runtime nodejs10 --trigger-http --allow-unauthenticated

You can use the following values for the --runtime flag to specify your preferred Node.js version:

• nodejs10
• nodejs12

Python

gcloud functions deploy hello_get \
--runtime python37 --trigger-http --allow-unauthenticated

You can use the following values for the --runtime flag to specify your preferred Python version:

• python37
• python38

Go

gcloud functions deploy HelloGet \
--runtime go111 --trigger-http --allow-unauthenticated

You can use the following values for the --runtime flag to specify your preferred Go version:

• go111
• go113

Java

gcloud functions deploy java-http-function \
--entry-point functions.HelloWorld \
--runtime java11 \
--memory 512MB --trigger-http --allow-unauthenticated

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

Triggering the function

To make an HTTP request to your function, run the following command:

Node.js

curl "https://REGION-PROJECT_ID.cloudfunctions.net/helloGET" 

Python

curl "https://REGION-PROJECT_ID.cloudfunctions.net/hello_get" 

Go

curl "https://REGION-PROJECT_ID.cloudfunctions.net/HelloGet" 

Java

curl "https://REGION-PROJECT_ID.cloudfunctions.net/java-http-function" 

where

• REGION is the region where your function is deployed. This is visible in your terminal when your function finishes deploying.
• PROJECT_ID is your Cloud project ID. This is visible in your terminal when your function finishes deploying.

You can also visit the deployed function's endpoint in your browser to see the "Hello World!" message.

Cleaning up

To avoid incurring charges to your Google Cloud Platform account for the resources used in this tutorial:

Deleting the project

The easiest way to eliminate billing is to delete the project that you created for the tutorial.

To delete the project:

Caution: Deleting a project has the following effects:

• Everything in the project is deleted. If you used an existing project for this tutorial, when you delete it, you also delete any other work you've done in the project.
• Custom project IDs are lost. When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an appspot.com URL, delete selected resources inside the project instead of deleting the whole project.

If you plan to explore multiple tutorials and quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the Cloud Console, go to the Manage resources page.

   Go to the Manage resources page

2. In the project list, select the project that you want to delete and then click Delete .
3. In the dialog, type the project ID and then click Shut down to delete the project.

Deleting the Cloud Function

Deleting Cloud Functions does not remove any resources stored in Cloud Storage.

To delete the Cloud Function you created in this tutorial, run the following command:

Node.js

gcloud functions delete helloGET 

Python

gcloud functions delete hello_get 

Go

gcloud functions delete HelloGet 

Java

gcloud functions delete java-http-function 

You can also delete Cloud Functions from the Google Cloud Console.