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Calling Cloud Functions Directly

To support quick iteration and debugging, Cloud Functions provides a call command in the command-line interface and testing functionality in the Google Cloud console UI. This allows you to directly invoke a function to ensure it is behaving as expected. This causes the function to execute immediately, even though it may have been deployed to respond to a specific event.

Using the Google Cloud CLI

To directly invoke a function using the gcloud CLI, use the gcloud functions call command and supply any data your function expects as JSON in the --data argument. For example:

gcloud functions call YOUR_FUNCTION_NAME --data '{"name":"Keyboard Cat"}'

where YOUR_FUNCTION_NAME is the name of the function you want to execute. The --data argument is sent to your function as follows:

  • For HTTP functions, the data you supply is sent as the body of a POST request.
  • For background functions, the data is passed directly as the event data to your function. For more information on accessing event data in background functions, see Background function parameters.
  • For CloudEvent functions, the data is passed directly as the event data to your function. For more information on accessing event data in CloudEvent functions, see CloudEvent function parameters.

Using the Google Cloud Console

To directly invoke a function from the Google Cloud console, follow these steps:

  1. Go to the Cloud Functions Overview page.

  2. From the list, click the name of the function you want to invoke.

    This takes you to the Function details page.

  3. Click the Testing tab.

  4. In the Triggering event field, enter any data your function expects as JSON.

  5. Click Test the function.

Your function's response appears in the Output field, and logs for the individual execution appear in the Logs field.

Cloud Pub/Sub event-driven function example

This example shows how to directly invoke an event-driven function triggered by Cloud Pub/Sub events:


 * Background Cloud Function to be triggered by Pub/Sub.
 * This function is exported by index.js, and executed when
 * the trigger topic receives a message.
 * @param {object} message The Pub/Sub message.
 * @param {object} context The event metadata.
exports.helloPubSub = (message, context) => {
  const name =
    ? Buffer.from(, 'base64').toString()
    : 'World';

  console.log(`Hello, ${name}!`);


def hello_pubsub(event, context):
    """Background Cloud Function to be triggered by Pub/Sub.
         event (dict):  The dictionary with data specific to this type of
                        event. The `@type` field maps to
                        The `data` field maps to the PubsubMessage data
                        in a base64-encoded string. The `attributes` field maps
                        to the PubsubMessage attributes if any is present.
         context ( Metadata of triggering event
                        including `event_id` which maps to the PubsubMessage
                        messageId, `timestamp` which maps to the PubsubMessage
                        publishTime, `event_type` which maps to
                        `google.pubsub.topic.publish`, and `resource` which is
                        a dictionary that describes the service API endpoint
              , the triggering topic's name, and
                        the triggering event type
        None. The output is written to Cloud Logging.
    import base64

    print("""This Function was triggered by messageId {} published at {} to {}
    """.format(context.event_id, context.timestamp, context.resource["name"]))

    if 'data' in event:
        name = base64.b64decode(event['data']).decode('utf-8')
        name = 'World'
    print('Hello {}!'.format(name))


// Package helloworld provides a set of Cloud Functions samples.
package helloworld

import (

// PubSubMessage is the payload of a Pub/Sub event.
// See the documentation for more details:
type PubSubMessage struct {
	Data []byte `json:"data"`

// HelloPubSub consumes a Pub/Sub message.
func HelloPubSub(ctx context.Context, m PubSubMessage) error {
	name := string(m.Data) // Automatically decoded from base64.
	if name == "" {
		name = "World"
	log.Printf("Hello, %s!", name)
	return nil


import functions.eventpojos.PubsubMessage;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.logging.Level;
import java.util.logging.Logger;

public class HelloPubSub implements BackgroundFunction<PubsubMessage> {
  private static final Logger logger = Logger.getLogger(HelloPubSub.class.getName());

  public void accept(PubsubMessage message, Context context) {
    String name = "world";
    if (message != null && message.getData() != null) {
      name = new String(
    }"Hello %s!", name));


using CloudNative.CloudEvents;
using Google.Cloud.Functions.Framework;
using Google.Events.Protobuf.Cloud.PubSub.V1;
using Microsoft.Extensions.Logging;
using System.Threading;
using System.Threading.Tasks;

namespace HelloPubSub
    public class Function : ICloudEventFunction<MessagePublishedData>
        private readonly ILogger _logger;

        public Function(ILogger<Function> logger) =>
            _logger = logger;

        public Task HandleAsync(CloudEvent cloudEvent, MessagePublishedData data, CancellationToken cancellationToken)
            string nameFromMessage = data.Message?.TextData;
            string name = string.IsNullOrEmpty(nameFromMessage) ? "world" : nameFromMessage;
            _logger.LogInformation("Hello {name}", name);
            return Task.CompletedTask;


require "functions_framework"
require "base64"

FunctionsFramework.cloud_event "hello_pubsub" do |event|
  # The event parameter is a CloudEvents::Event::V1 object.
  # See
  name = Base64.decode64["message"]["data"] rescue "World"

  # A cloud_event function does not return a response, but you can log messages
  # or cause side effects such as sending additional events. "Hello, #{name}!"


use CloudEvents\V1\CloudEventInterface;
use Google\CloudFunctions\FunctionsFramework;

// Register the function with Functions Framework.
// This enables omitting the `FUNCTIONS_SIGNATURE_TYPE=cloudevent` environment
// variable when deploying. The `FUNCTION_TARGET` environment variable should
// match the first parameter.
FunctionsFramework::cloudEvent('helloworldPubsub', 'helloworldPubsub');

function helloworldPubsub(CloudEventInterface $event): void
    $log = fopen(getenv('LOGGER_OUTPUT') ?: 'php://stderr', 'wb');

    $cloudEventData = $event->getData();
    $pubSubData = base64_decode($cloudEventData['message']['data']);

    $name = $pubSubData ? htmlspecialchars($pubSubData) : 'World';
    fwrite($log, "Hello, $name!" . PHP_EOL);

To directly invoke the function, you need to send a PubsubMessage, which expects base64-encoded data, as the event data:


DATA=$(printf 'Hello!'|base64) && gcloud functions call helloPubSub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call hello_pubsub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call HelloPubSub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call java-hello-pubsub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call csharp-hello-pubsub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call hello_pubsub --data '{"data":"'$DATA'"}'


DATA=$(printf 'Hello!'|base64) && gcloud functions call helloworldPubsub --data '{"data":"'$DATA'"}'

You can also invoke the function from the Google Cloud console UI: simply use the same event data in the Triggering event field.