Configure CORS for a bucket

Add a CORS configuration to a Cloud Storage bucket.

Explore further

For detailed documentation that includes this code sample, see the following:

• Set up and view CORS configurations

Code sample

C++

For more information, see the Cloud Storage C++ API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& origin) {
  StatusOr<gcs::BucketMetadata> original =
      client.GetBucketMetadata(bucket_name);

  if (!original) throw std::move(original).status();
  std::vector<gcs::CorsEntry> cors_configuration;
  cors_configuration.emplace_back(
      gcs::CorsEntry{3600, {"GET"}, {origin}, {"Content-Type"}});

  StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
      bucket_name,
      gcs::BucketMetadataPatchBuilder().SetCors(cors_configuration),
      gcs::IfMetagenerationMatch(original->metageneration()));
  if (!patched) throw std::move(patched).status();

  if (patched->cors().empty()) {
    std::cout << "Cors configuration is not set for bucket "
              << patched->name() << "\n";
    return;
  }

  std::cout << "Cors configuration successfully set for bucket "
            << patched->name() << "\nNew cors configuration: ";
  for (auto const& cors_entry : patched->cors()) {
    std::cout << "\n  " << cors_entry << "\n";
  }
}

C#

For more information, see the Cloud Storage C# API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;
using static Google.Apis.Storage.v1.Data.Bucket;

public class BucketAddCorsConfigurationSample
{
    public Bucket BucketAddCorsConfiguration(string bucketName = "your-bucket-name")
    {
        var storage = StorageClient.Create();
        var bucket = storage.GetBucket(bucketName);

        CorsData corsData = new CorsData
        {
            Origin = new string[] { "*" },
            ResponseHeader = new string[] { "Content-Type", "x-goog-resumable" },
            Method = new string[] { "PUT", "POST" },
            MaxAgeSeconds = 3600 //One Hour
        };

        if (bucket.Cors == null)
        {
            bucket.Cors = new List<CorsData>();
        }
        bucket.Cors.Add(corsData);

        bucket = storage.UpdateBucket(bucket);
        Console.WriteLine($"bucketName {bucketName} was updated with a CORS config to allow {string.Join(",", corsData.Method)} requests from" +
            $" {string.Join(",", corsData.Origin)} sharing {string.Join(",", corsData.ResponseHeader)} responseHeader" +
            $" responses across origins.");
        return bucket;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/storage"
)

// setBucketCORSConfiguration sets a CORS configuration on a bucket.
func setBucketCORSConfiguration(w io.Writer, bucketName string, maxAge time.Duration, methods, origins, responseHeaders []string) error {
	// bucketName := "bucket-name"
	// maxAge := time.Hour
	// methods := []string{"GET"}
	// origins := []string{"some-origin.com"}
	// responseHeaders := []string{"Content-Type"}
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	bucket := client.Bucket(bucketName)
	bucketAttrsToUpdate := storage.BucketAttrsToUpdate{
		CORS: []storage.CORS{
			{
				MaxAge:          maxAge,
				Methods:         methods,
				Origins:         origins,
				ResponseHeaders: responseHeaders,
			}},
	}
	if _, err := bucket.Update(ctx, bucketAttrsToUpdate); err != nil {
		return fmt.Errorf("Bucket(%q).Update: %w", bucketName, err)
	}
	fmt.Fprintf(w, "Bucket %v was updated with a CORS config to allow %v requests from %v sharing %v responses across origins\n", bucketName, methods, origins, responseHeaders)
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Cors;
import com.google.cloud.storage.HttpMethod;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import com.google.common.collect.ImmutableList;

public class ConfigureBucketCors {
  public static void configureBucketCors(
      String projectId,
      String bucketName,
      String origin,
      String responseHeader,
      Integer maxAgeSeconds) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The origin for this CORS config to allow requests from
    // String origin = "http://example.appspot.com";

    // The response header to share across origins
    // String responseHeader = "Content-Type";

    // The maximum amount of time the browser can make requests before it must repeat preflighted
    // requests
    // Integer maxAgeSeconds = 3600;

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();
    Bucket bucket = storage.get(bucketName);

    // See the HttpMethod documentation for other HTTP methods available:
    // https://cloud.google.com/appengine/docs/standard/java/javadoc/com/google/appengine/api/urlfetch/HTTPMethod
    HttpMethod method = HttpMethod.GET;

    Cors cors =
        Cors.newBuilder()
            .setOrigins(ImmutableList.of(Cors.Origin.of(origin)))
            .setMethods(ImmutableList.of(method))
            .setResponseHeaders(ImmutableList.of(responseHeader))
            .setMaxAgeSeconds(maxAgeSeconds)
            .build();

    bucket.toBuilder().setCors(ImmutableList.of(cors)).build().update();

    System.out.println(
        "Bucket "
            + bucketName
            + " was updated with a CORS config to allow GET requests from "
            + origin
            + " sharing "
            + responseHeader
            + " responses across origins");
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The origin for this CORS config to allow requests from
// const origin = 'http://example.appspot.com';

// The response header to share across origins
// const responseHeader = 'Content-Type';

// The maximum amount of time the browser can make requests before it must
// repeat preflighted requests
// const maxAgeSeconds = 3600;

// The name of the method
// See the HttpMethod documentation for other HTTP methods available:
// https://cloud.google.com/appengine/docs/standard/java/javadoc/com/google/appengine/api/urlfetch/HTTPMethod
// const method = 'GET';

async function configureBucketCors() {
  await storage.bucket(bucketName).setCorsConfiguration([
    {
      maxAgeSeconds,
      method: [method],
      origin: [origin],
      responseHeader: [responseHeader],
    },
  ]);

  console.log(`Bucket ${bucketName} was updated with a CORS config
      to allow ${method} requests from ${origin} sharing 
      ${responseHeader} responses across origins`);
}

configureBucketCors().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

use Google\Cloud\Storage\StorageClient;

/**
 * Update the CORS configuration of a bucket.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $method The HTTP method for the CORS config. (e.g. 'GET')
 * @param string $origin The origin from which the CORS config will allow requests.
 *        (e.g. 'http://example.appspot.com')
 * @param string $responseHeader The response header to share across origins.
 *        (e.g. 'Content-Type')
 * @param int $maxAgeSeconds The maximum amount of time the browser can make
 *        (e.g. 3600)
 *     requests before it must repeat preflighted requests.
 */
function cors_configuration(string $bucketName, string $method, string $origin, string $responseHeader, int $maxAgeSeconds): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $bucket->update([
        'cors' => [
            [
                'method' => [$method],
                'origin' => [$origin],
                'responseHeader' => [$responseHeader],
                'maxAgeSeconds' => $maxAgeSeconds,
            ]
        ]
    ]);

    printf(
        'Bucket %s was updated with a CORS config to allow GET requests from ' .
        '%s sharing %s responses across origins.',
        $bucketName,
        $origin,
        $responseHeader
    );
}

Python

For more information, see the Cloud Storage Python API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

from google.cloud import storage


def cors_configuration(bucket_name):
    """Set a bucket's CORS policies configuration."""
    # bucket_name = "your-bucket-name"

    storage_client = storage.Client()
    bucket = storage_client.get_bucket(bucket_name)
    bucket.cors = [
        {
            "origin": ["*"],
            "responseHeader": [
                "Content-Type",
                "x-goog-resumable"],
            "method": ['PUT', 'POST'],
            "maxAgeSeconds": 3600
        }
    ]
    bucket.patch()

    print(f"Set CORS policies for bucket {bucket.name} is {bucket.cors}")
    return bucket

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

To authenticate to Cloud Storage, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

def cors_configuration bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  bucket.cors do |c|
    c.add_rule ["*"],
               ["PUT", "POST"],
               headers: [
                 "Content-Type",
                 "x-goog-resumable"
               ],
               max_age: 3600
  end

  puts "Set CORS policies for bucket #{bucket_name}"
end

What's next

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