Cloud Storage Tutorial

---

Note: This content applies only to Cloud Run functions—formerly Cloud Functions (2nd gen).

For the 1st gen version of this document, see the Cloud Storage tutorial (1st gen).

This simple tutorial demonstrates writing, deploying, and triggering an Event-Driven Cloud Run function with a Cloud Storage trigger to respond to Cloud Storage events.

Note: Events are delivered using Pub/Sub notifications from Cloud Storage. A bucket can have up to 10 notification configurations set to trigger for a specific event. Setting up too many notifications for the same bucket might exceed the notifications limit for the bucket and make it impossible to create a function, as indicated by the error Cloud Storage bucket ...: Pub/Sub notification limit reached. If you reach the limit, you can't create a function until you take remedial action, such as removing notifications.

Visit the Google Cloud sample browser if you're looking for code samples for using Cloud Storage.

Objectives

• Write and deploy an Event-Driven Cloud Run function.
• Trigger the function by uploading a file to Cloud Storage.

Costs

In this document, you use the following billable components of Google Cloud:

• Cloud Run functions
• Cloud Build
• Pub/Sub
• Cloud Storage
• Artifact Registry
• Eventarc
• Cloud Logging

For details, see Cloud Run functions pricing.

To generate a cost estimate based on your projected usage, use the pricing calculator. New Google Cloud users might be eligible for a free trial.

Before you begin

1. 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.

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

3. Make sure that billing is enabled for your Google Cloud project.

4. Enable the Cloud Functions, Cloud Build, Artifact Registry, Eventarc, Logging, and Pub/Sub APIs.

   Enable the APIs

5. Install the Google Cloud CLI.

6. To initialize the gcloud CLI, run the following command:

   gcloud init

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

8. Make sure that billing is enabled for your Google Cloud project.

9. Enable the Cloud Functions, Cloud Build, Artifact Registry, Eventarc, Logging, and Pub/Sub APIs.

   Enable the APIs

10. Install the Google Cloud CLI.

11. To initialize the gcloud CLI, run the following command:

    gcloud init

If you already have the gcloud CLI installed, update it by running the following command:

gcloud components update

Note: Make sure the runtime service account key you are using for your Application Default Credentials has either the cloudfunctions.serviceAgent role or the storage.buckets.{get, update} and the resourcemanager.projects.get permissions. For more information on setting these permissions, see Granting, changing, and revoking access to resources.
12. 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

    C#

    Go to the .NET setup guide

    Ruby

    Go to the Ruby setup guide

    PHP

    Go to Using PHP on Google Cloud

Prerequisites

1. Create a regional bucket, where YOUR_BUCKET_NAME is a globally unique bucket name, and REGION is the region in which you plan to deploy your function:

   gcloud storage buckets create gs://YOUR_BUCKET_NAME --location=REGION

2. To use Cloud Storage functions, grant the pubsub.publisher role to the Cloud Storage service account:

   PROJECT_ID=$(gcloud config get-value project)
   PROJECT_NUMBER=$(gcloud projects list --filter="project_id:$PROJECT_ID" --format='value(project_number)')
   
   SERVICE_ACCOUNT=$(gcloud storage service-agent --project=$PROJECT_ID)
   
   gcloud projects add-iam-policy-binding $PROJECT_ID \
     --member serviceAccount:$SERVICE_ACCOUNT \
     --role roles/pubsub.publisher
   

Prepare 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.

   C#

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

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

   Ruby

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

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

   PHP

   git clone https://github.com/GoogleCloudPlatform/php-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 Run functions sample code:

   Node.js

   cd nodejs-docs-samples/functions/v2/helloGCS/

   Python

   cd python-docs-samples/functions/v2/storage/

   Go

   cd golang-samples/functions/functionsv2/hellostorage/

   Java

   cd java-docs-samples/functions/v2/hello-gcs/

   C#

   cd dotnet-docs-samples/functions/helloworld/HelloGcs/

   Ruby

   cd ruby-docs-samples/functions/helloworld/storage/

   PHP

   cd php-docs-samples/functions/helloworld_storage/

Deploy and trigger the function

Cloud Storage functions are based on Pub/Sub notifications from Cloud Storage and support similar event types:

• finalize

• delete

• archive

• metadata update

The following sections describe how to deploy and trigger a function for each of these event types.

Object Finalize

Object finalize events trigger when a "write" of a Cloud Storage Object is successfully finalized. In particular, this means that creating a new object or overwriting an existing object triggers this event. Archive and metadata update operations are ignored by this trigger.

Object Finalize: deploy the function

Take a look at the sample function, which handles Cloud Storage events:

Node.js

const functions = require('@google-cloud/functions-framework');

// Register a CloudEvent callback with the Functions Framework that will
// be triggered by Cloud Storage.
functions.cloudEvent('helloGCS', cloudEvent => {
  console.log(`Event ID: ${cloudEvent.id}`);
  console.log(`Event Type: ${cloudEvent.type}`);

  const file = cloudEvent.data;
  console.log(`Bucket: ${file.bucket}`);
  console.log(`File: ${file.name}`);
  console.log(`Metageneration: ${file.metageneration}`);
  console.log(`Created: ${file.timeCreated}`);
  console.log(`Updated: ${file.updated}`);
});

Python

from cloudevents.http import CloudEvent

import functions_framework


# Triggered by a change in a storage bucket
@functions_framework.cloud_event
def hello_gcs(cloud_event: CloudEvent) -> tuple:
    """This function is triggered by a change in a storage bucket.

    Args:
        cloud_event: The CloudEvent that triggered this function.
    Returns:
        The event ID, event type, bucket, name, metageneration, and timeCreated.
    """
    data = cloud_event.data

    event_id = cloud_event["id"]
    event_type = cloud_event["type"]

    bucket = data["bucket"]
    name = data["name"]
    metageneration = data["metageneration"]
    timeCreated = data["timeCreated"]
    updated = data["updated"]

    print(f"Event ID: {event_id}")
    print(f"Event type: {event_type}")
    print(f"Bucket: {bucket}")
    print(f"File: {name}")
    print(f"Metageneration: {metageneration}")
    print(f"Created: {timeCreated}")
    print(f"Updated: {updated}")

    return event_id, event_type, bucket, name, metageneration, timeCreated, updated

Go

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

import (
	"context"
	"fmt"
	"log"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
	"github.com/googleapis/google-cloudevents-go/cloud/storagedata"
	"google.golang.org/protobuf/encoding/protojson"
)

func init() {
	functions.CloudEvent("HelloStorage", helloStorage)
}

// helloStorage consumes a CloudEvent message and logs details about the changed object.
func helloStorage(ctx context.Context, e event.Event) error {
	log.Printf("Event ID: %s", e.ID())
	log.Printf("Event Type: %s", e.Type())

	var data storagedata.StorageObjectData
	if err := protojson.Unmarshal(e.Data(), &data); err != nil {
		return fmt.Errorf("protojson.Unmarshal: %w", err)
	}

	log.Printf("Bucket: %s", data.GetBucket())
	log.Printf("File: %s", data.GetName())
	log.Printf("Metageneration: %d", data.GetMetageneration())
	log.Printf("Created: %s", data.GetTimeCreated().AsTime())
	log.Printf("Updated: %s", data.GetUpdated().AsTime())
	return nil
}

Java

import com.google.cloud.functions.CloudEventsFunction;
import com.google.events.cloud.storage.v1.StorageObjectData;
import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.util.JsonFormat;
import io.cloudevents.CloudEvent;
import java.nio.charset.StandardCharsets;
import java.util.logging.Logger;

public class HelloGcs implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(HelloGcs.class.getName());

  @Override
  public void accept(CloudEvent event) throws InvalidProtocolBufferException {
    logger.info("Event: " + event.getId());
    logger.info("Event Type: " + event.getType());

    if (event.getData() == null) {
      logger.warning("No data found in cloud event payload!");
      return;
    }

    String cloudEventData = new String(event.getData().toBytes(), StandardCharsets.UTF_8);
    StorageObjectData.Builder builder = StorageObjectData.newBuilder();
    JsonFormat.parser().merge(cloudEventData, builder);
    StorageObjectData data = builder.build();

    logger.info("Bucket: " + data.getBucket());
    logger.info("File: " + data.getName());
    logger.info("Metageneration: " + data.getMetageneration());
    logger.info("Created: " + data.getTimeCreated());
    logger.info("Updated: " + data.getUpdated());
  }
}

C#

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

namespace HelloGcs;

 /// <summary>
 /// Example Cloud Storage-triggered function.
 /// This function can process any event from Cloud Storage.
 /// </summary>
public class Function : ICloudEventFunction<StorageObjectData>
{
    private readonly ILogger _logger;

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

    public Task HandleAsync(CloudEvent cloudEvent, StorageObjectData data, CancellationToken cancellationToken)
    {
        _logger.LogInformation("Event: {event}", cloudEvent.Id);
        _logger.LogInformation("Event Type: {type}", cloudEvent.Type);
        _logger.LogInformation("Bucket: {bucket}", data.Bucket);
        _logger.LogInformation("File: {file}", data.Name);
        _logger.LogInformation("Metageneration: {metageneration}", data.Metageneration);
        _logger.LogInformation("Created: {created:s}", data.TimeCreated?.ToDateTimeOffset());
        _logger.LogInformation("Updated: {updated:s}", data.Updated?.ToDateTimeOffset());
        return Task.CompletedTask;
    }
}

Ruby

require "functions_framework"

FunctionsFramework.cloud_event "hello_gcs" do |event|
  # This function supports all Cloud Storage events.
  # The `event` parameter is a CloudEvents::Event::V1 object.
  # See https://cloudevents.github.io/sdk-ruby/latest/CloudEvents/Event/V1.html
  payload = event.data

  logger.info "Event: #{event.id}"
  logger.info "Event Type: #{event.type}"
  logger.info "Bucket: #{payload['bucket']}"
  logger.info "File: #{payload['name']}"
  logger.info "Metageneration: #{payload['metageneration']}"
  logger.info "Created: #{payload['timeCreated']}"
  logger.info "Updated: #{payload['updated']}"
end

PHP

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('helloGCS', 'helloGCS');

function helloGCS(CloudEventInterface $cloudevent)
{
    // This function supports all Cloud Storage event types.
    $log = fopen(getenv('LOGGER_OUTPUT') ?: 'php://stderr', 'wb');
    $data = $cloudevent->getData();
    fwrite($log, 'Event: ' . $cloudevent->getId() . PHP_EOL);
    fwrite($log, 'Event Type: ' . $cloudevent->getType() . PHP_EOL);
    fwrite($log, 'Bucket: ' . $data['bucket'] . PHP_EOL);
    fwrite($log, 'File: ' . $data['name'] . PHP_EOL);
    fwrite($log, 'Metageneration: ' . $data['metageneration'] . PHP_EOL);
    fwrite($log, 'Created: ' . $data['timeCreated'] . PHP_EOL);
    fwrite($log, 'Updated: ' . $data['updated'] . PHP_EOL);
}

To deploy the function, run the following command in the directory where the sample code is located:

Node.js

gcloud functions deploy nodejs-finalize-function \
--gen2 \
--runtime=nodejs22 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Node.js version to run your function.

Python

gcloud functions deploy python-finalize-function \
--gen2 \
--runtime=python312 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Python version to run your function.

Go

gcloud functions deploy go-finalize-function \
--gen2 \
--runtime=go122 \
--region=REGION \
--source=. \
--entry-point=HelloStorage \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Go version to run your function.

Java

gcloud functions deploy java-finalize-function \
--gen2 \
--runtime=java21 \
--region=REGION \
--source=. \
--entry-point=functions.HelloGcs \
--memory=512MB \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Java version to run your function.

C#

gcloud functions deploy csharp-finalize-function \
--gen2 \
--runtime=dotnet8 \
--region=REGION \
--source=. \
--entry-point=HelloGcs.Function \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported .NET version to run your function.

Ruby

gcloud functions deploy ruby-finalize-function \
--gen2 \
--runtime=ruby33 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Ruby version to run your function.

PHP

gcloud functions deploy php-finalize-function \
--gen2 \
--runtime=php83 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.finalized" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported PHP version to run your function.

Replace the following:

• REGION: The name of the Google Cloud region where you want to deploy your function (for example, us-west1).
• YOUR_BUCKET_NAME: The name of the Cloud Storage bucket that triggers the function. When deploying Cloud Run functions, specify the bucket name alone without the leading gs://; for example, --trigger-event-filters="bucket=my-bucket".

Object Finalize: trigger the function

Test the function by uploading a file to your bucket:

echo "Hello World" > test-finalize.txt
gcloud storage cp test-finalize.txt gs://YOUR_BUCKET_NAME/test-finalize.txt

You should see the received CloudEvent in the logs:

gcloud functions logs read YOUR_FUNCTION_NAME --region REGION --gen2 --limit=10

Object Delete

Object delete events are most useful for non-versioning buckets. They are triggered when an old version of an object is deleted. In addition, they are triggered when an object is overwritten. Object delete triggers can also be used with versioning buckets, triggering when a version of an object is permanently deleted.

Object Delete: deploy the function

Using the same sample code as in the finalize example, deploy the function with object delete as the trigger event. Run the following command in the directory where the sample code is located:

Node.js

gcloud functions deploy nodejs-delete-function \
--gen2 \
--runtime=nodejs22 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Node.js version to run your function.

Python

gcloud functions deploy python-delete-function \
--gen2 \
--runtime=python312 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Python version to run your function.

Go

gcloud functions deploy go-delete-function \
--gen2 \
--runtime=go122 \
--region=REGION \
--source=. \
--entry-point=HelloStorage \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Go version to run your function.

Java

gcloud functions deploy java-delete-function \
--gen2 \
--runtime=java21 \
--region=REGION \
--source=. \
--entry-point=functions.HelloGcs \
--memory=512MB \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Java version to run your function.

C#

gcloud functions deploy csharp-delete-function \
--gen2 \
--runtime=dotnet8 \
--region=REGION \
--source=. \
--entry-point=HelloGcs.Function \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported .NET version to run your function.

Ruby

gcloud functions deploy ruby-delete-function \
--gen2 \
--runtime=ruby33 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Ruby version to run your function.

PHP

gcloud functions deploy php-delete-function \
--gen2 \
--runtime=php83 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.deleted" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported PHP version to run your function.

Replace the following:

• REGION: The name of the Google Cloud region where you want to deploy your function (for example, us-west1).
• YOUR_BUCKET_NAME: The name of the Cloud Storage bucket that triggers the function. When deploying Cloud Run functions, specify the bucket name alone without the leading gs://; for example, --trigger-event-filters="bucket=my-bucket".

Object Delete: trigger the function

To trigger the function:

1. Create an empty test-delete.txt file in the directory where the sample code is located.

2. Make sure that your bucket is non-versioning:

   gcloud storage buckets update gs://YOUR_BUCKET_NAME --no-versioning

3. Upload the file to Cloud Storage:

   gcloud storage cp test-delete.txt gs://YOUR_BUCKET_NAME

   where YOUR_BUCKET_NAME is the name of your Cloud Storage bucket where you will upload a test file. At this point the function should not execute yet.

4. Delete the file to trigger the function:

   gcloud storage rm gs://YOUR_BUCKET_NAME/test-delete.txt

5. You should see the received CloudEvent in the logs:

   gcloud functions logs read YOUR_FUNCTION_NAME --region REGION --gen2 --limit=10

Note that the function may take some time to finish executing.

Object Archive

Object archive events can be used only with versioning buckets. They are triggered when an earlier version of an object is archived. In particular, this means that when an object is overwritten or deleted, an archive event is triggered.

Object Archive: deploy the function

Using the same sample code as in the finalize example, deploy the function with object archive as the trigger event. Run the following command in the directory where the sample code is located:

Node.js

gcloud functions deploy nodejs-archive-function \
--gen2 \
--runtime=nodejs22 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Node.js version to run your function.

Python

gcloud functions deploy python-archive-function \
--gen2 \
--runtime=python312 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Python version to run your function.

Go

gcloud functions deploy go-archive-function \
--gen2 \
--runtime=go122 \
--region=REGION \
--source=. \
--entry-point=HelloStorage \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Go version to run your function.

Java

gcloud functions deploy java-archive-function \
--gen2 \
--runtime=java21 \
--region=REGION \
--source=. \
--entry-point=functions.HelloGcs \
--memory=512MB \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Java version to run your function.

C#

gcloud functions deploy csharp-archive-function \
--gen2 \
--runtime=dotnet8 \
--region=REGION \
--source=. \
--entry-point=HelloGcs.Function \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported .NET version to run your function.

Ruby

gcloud functions deploy ruby-archive-function \
--gen2 \
--runtime=ruby33 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Ruby version to run your function.

PHP

gcloud functions deploy php-archive-function \
--gen2 \
--runtime=php83 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.archived" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported PHP version to run your function.

Replace the following:

• REGION: The name of the Google Cloud region where you want to deploy your function (for example, us-west1).
• YOUR_BUCKET_NAME: The name of the Cloud Storage bucket that triggers the function. When deploying Cloud Run functions, specify the bucket name alone without the leading gs://; for example, --trigger-event-filters="bucket=my-bucket".

Object Archive: trigger the function

To trigger the function:

1. Create an empty test-archive.txt file in the directory where the sample code is located.

2. Make sure that your bucket has versioning enabled:

    gcloud storage buckets update gs://YOUR_BUCKET_NAME --versioning

3. Upload the file to Cloud Storage:

   gcloud storage cp test-archive.txt gs://YOUR_BUCKET_NAME

   where YOUR_BUCKET_NAME is the name of your Cloud Storage bucket where you will upload a test file. At this point the function should not execute yet.

4. Archive the file to trigger the function:

   gcloud storage rm gs://YOUR_BUCKET_NAME/test-archive.txt

5. You should see the received CloudEvent in the logs:

   gcloud functions logs read YOUR_FUNCTION_NAME --region REGION --gen2 --limit=10

Object Metadata Update

Metadata update events are triggered when the metadata of existing object is updated.

Object Metadata Update: deploy the function

Using the same sample code as in the finalize example, deploy the function with metadata update as the trigger event. Run the following command in the directory where the sample code is located:

Node.js

gcloud functions deploy nodejs-metadata-function \
--gen2 \
--runtime=nodejs22 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Node.js version to run your function.

Python

gcloud functions deploy python-metadata-function \
--gen2 \
--runtime=python312 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Python version to run your function.

Go

gcloud functions deploy go-metadata-function \
--gen2 \
--runtime=go122 \
--region=REGION \
--source=. \
--entry-point=HelloStorage \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Go version to run your function.

Java

gcloud functions deploy java-metadata-function \
--gen2 \
--runtime=java21 \
--region=REGION \
--source=. \
--entry-point=functions.HelloGcs \
--memory=512MB \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Java version to run your function.

C#

gcloud functions deploy csharp-metadata-function \
--gen2 \
--runtime=dotnet8 \
--region=REGION \
--source=. \
--entry-point=HelloGcs.Function \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported .NET version to run your function.

Ruby

gcloud functions deploy ruby-metadata-function \
--gen2 \
--runtime=ruby33 \
--region=REGION \
--source=. \
--entry-point=hello_gcs \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported Ruby version to run your function.

PHP

gcloud functions deploy php-metadata-function \
--gen2 \
--runtime=php83 \
--region=REGION \
--source=. \
--entry-point=helloGCS \
--trigger-event-filters="type=google.cloud.storage.object.v1.metadataUpdated" \
--trigger-event-filters="bucket=YOUR_BUCKET_NAME"

Use the --runtime flag to specify the runtime ID of a supported PHP version to run your function.

Replace the following:

• REGION: The name of the Google Cloud region where you want to deploy your function (for example, us-west1).
• YOUR_BUCKET_NAME: The name of the Cloud Storage bucket that triggers the function. When deploying Cloud Run functions, specify the bucket name alone without the leading gs://; for example, --trigger-event-filters="bucket=my-bucket".

Object Metadata Update: trigger the function

To trigger the function:

1. Create an empty test-metadata.txt file in the directory where the sample code is located.

2. Make sure that your bucket is non-versioning:

   gcloud storage buckets update gs://YOUR_BUCKET_NAME --no-versioning

3. Upload the file to Cloud Storage:

   gcloud storage cp test-metadata.txt gs://YOUR_BUCKET_NAME

   where YOUR_BUCKET_NAME is the name of your Cloud Storage bucket where you will upload a test file. At this point the function should not execute yet.

4. Update the metadata of the file:

   gcloud storage objects update gs://YOUR_BUCKET_NAME/test-metadata.txt --content-type=text/plain

5. You should see the received CloudEvent in the logs:

   gcloud functions logs read YOUR_FUNCTION_NAME --region REGION --gen2 --limit=10

Clean up

To avoid incurring charges to your Google Cloud account for the resources used in this tutorial, either delete the project that contains the resources, or keep the project and delete the individual resources.

Delete 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 the tasks in this document, 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 architectures, tutorials, or quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the Google Cloud console, go to the Manage resources page.

   Go to Manage resources

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.

Delete the function

Deleting Cloud Run functions does not remove any resources stored in Cloud Storage.

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

gcloud functions delete YOUR_FUNCTION_NAME --gen2 --region REGION

You can also delete Cloud Run functions from the Google Cloud console.

What's next

• Learn how to perform OCR on images uploaded to a bucket.
• Learn how to translate text files using Cloud Run functions.