Upload an object with HTML forms

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name, std::string const& signing_account) {
  auto document = client.GenerateSignedPostPolicyV4(
      gcs::PolicyDocumentV4{
          bucket_name,
          object_name,
          /*expiration=*/std::chrono::minutes(10),
      },
      gcs::AddExtensionFieldOption("x-goog-meta-test", "data"),
      gcs::SigningAccount(signing_account));
  if (!document) throw std::move(document).status();

  // Create the HTML form for the computed policy.
  std::ostringstream os;
  os << "<form action='" << document->url << "' method='POST'"
     << " enctype='multipart/form-data'>\n";
  for (auto const& field : document->required_form_fields) {
    os << "  <input name='" << field.first << "' value='" << field.second
       << "' type='hidden' />\n";
  }
  os << "  <input type='submit' value='Upload File' /><br />\n"
     << "  <input type='file' name='file' /><br />\n"
     << "</form>";

  std::cout << "A sample HTML form:\n" << os.str() << "\n";
}

// Create a signed post policy which can be used to upload a specific object and
// expires in 1 hour after creation.
UrlSigner urlSigner = UrlSigner.FromCredential(credential);
UrlSigner.Options options = UrlSigner.Options
    .FromDuration(TimeSpan.FromHours(1))
    .WithSigningVersion(SigningVersion.V4)
    .WithScheme("https");
UrlSigner.PostPolicy postPolicy = UrlSigner.PostPolicy.ForBucketAndKey(bucketName, objectName);
postPolicy.SetCustomField(UrlSigner.PostPolicyCustomElement.GoogleMetadata, "x-goog-meta-test", "data");

UrlSigner.SignedPostPolicy signedPostPolicy = await urlSigner.SignAsync(postPolicy, options);

// Create an HTML form including all the fields in the signed post policy.
StringBuilder form = new StringBuilder();
form.AppendLine($"<form action=\"{signedPostPolicy.PostUrl}\" method=\"post\" enctype=\"multipart/form-data\">");
foreach (var field in signedPostPolicy.Fields)
{
    form.AppendLine($"<input type=\"hidden\" name=\"{field.Key}\" value=\"{field.Value}\">");
}
// Include the file element. It should always be the last element in the form.
form.AppendLine("<input name=\"file\" type=\"file\">");
form.AppendLine("<input type=\"submit\" value=\"Upload\">");
form.AppendLine("</form>");

// You can now save the form to file and serve it as static content
// or send it as the response to a request made to your application.
File.WriteAllText("PostPolicySimple.html", form.ToString());

import com.google.cloud.storage.BlobInfo;
import com.google.cloud.storage.PostPolicyV4;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.Map;
import java.util.concurrent.TimeUnit;

public class GenerateSignedPostPolicyV4 {
  /**
   * Generating a signed POST policy requires Credentials which implement ServiceAccountSigner.
   * These can be set explicitly using the Storage.PostPolicyV4Option.signWith(ServiceAccountSigner)
   * option. If you don't, you could also pass a service account signer to StorageOptions, i.e.
   * StorageOptions().newBuilder().setCredentials(ServiceAccountSignerCredentials). In this example,
   * neither of these options are used, which means the following code only works when the
   * credentials are defined via the environment variable GOOGLE_APPLICATION_CREDENTIALS, and those
   * credentials are authorized to sign a policy. See the documentation for
   * Storage.generateSignedPostPolicyV4 for more details.
   */
  public static void generateSignedPostPolicyV4(
      String projectId, String bucketName, String blobName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of the GCS bucket to upload to
    // String bucketName = "your-bucket-name"

    // The name to give the object uploaded to GCS
    // String blobName = "your-object-name"

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    PostPolicyV4.PostFieldsV4 fields =
        PostPolicyV4.PostFieldsV4.newBuilder().setCustomMetadataField("test", "data").build();

    PostPolicyV4 policy =
        storage.generateSignedPostPolicyV4(
            BlobInfo.newBuilder(bucketName, blobName).build(), 10, TimeUnit.MINUTES, fields);

    StringBuilder htmlForm =
        new StringBuilder(
            "<form action='"
                + policy.getUrl()
                + "' method='POST' enctype='multipart/form-data'>\n");
    for (Map.Entry<String, String> entry : policy.getFields().entrySet()) {
      htmlForm.append(
          "  <input name='"
              + entry.getKey()
              + "' value='"
              + entry.getValue()
              + "' type='hidden' />\n");
    }
    htmlForm.append("  <input type='file' name='file'/><br />\n");
    htmlForm.append("  <input type='submit' value='Upload File'/><br />\n");
    htmlForm.append("</form>\n");

    System.out.println(
        "You can use the following HTML form to upload an object to bucket "
            + bucketName
            + " for the next ten minutes:");
    System.out.println(htmlForm.toString());
  }
}

import (
	"context"
	"fmt"
	"html/template"
	"io"
	"time"

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

// form is a template for an HTML form that will use the data from the signed
// post policy.
var form = `<form action="{{ .URL }}" method="POST" enctype="multipart/form-data">
	{{- range $name, $value := .Fields }}
	<input name="{{ $name }}" value="{{ $value }}" type="hidden"/>
	{{- end }}
	<input type="file" name="file"/><br />
	<input type="submit" value="Upload File" name="submit"/><br />
</form>`

var tmpl = template.Must(template.New("policyV4").Parse(form))

// generateSignedPostPolicyV4 generates a signed post policy.
func generateSignedPostPolicyV4(w io.Writer, bucket, object string) (*storage.PostPolicyV4, error) {
	// bucket := "bucket-name"
	// object := "object-name"

	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	metadata := map[string]string{
		"x-goog-meta-test": "data",
	}

	// Generating a signed POST policy requires credentials authorized to sign a URL.
	// You can pass these in through PostPolicyV4Options with one of the following options:
	//    a. a Google service account private key, obtainable from the Google Developers Console
	//    b. a Google Access ID with iam.serviceAccounts.signBlob permissions
	//    c. a SignBytes function implementing custom signing
	// In this example, none of these options are used, which means the
	// GenerateSignedPostPolicyV4 function attempts to use the same authentication
	// that was used to instantiate	the Storage client. This authentication must
	// include a private key or have iam.serviceAccounts.signBlob permissions.
	opts := &storage.PostPolicyV4Options{
		Expires: time.Now().Add(10 * time.Minute),
		Fields: &storage.PolicyV4Fields{
			Metadata: metadata,
		},
	}

	policy, err := client.Bucket(bucket).GenerateSignedPostPolicyV4(object, opts)
	if err != nil {
		return nil, fmt.Errorf("storage.GenerateSignedPostPolicyV4: %w", err)
	}

	// Generate the form, using the data from the policy.
	if err = tmpl.Execute(w, policy); err != nil {
		return policy, fmt.Errorf("executing template: %w", err)
	}

	return policy, nil
}

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

// The ID of your GCS file
// const fileName = 'your-file-name';

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

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

async function generateV4SignedPolicy() {
  const bucket = storage.bucket(bucketName);
  const file = bucket.file(fileName);

  // These options will allow temporary uploading of a file
  // through an HTML form.
  const expires = Date.now() + 10 * 60 * 1000; //  10 minutes
  const options = {
    expires,
    fields: {'x-goog-meta-test': 'data'},
  };

  // Get a v4 signed policy for uploading file
  const [response] = await file.generateSignedPostPolicyV4(options);

  // Create an HTML form with the provided policy
  let output = `<form action="${response.url}" method="POST" enctype="multipart/form-data">\n`;
  // Include all fields returned in the HTML form as they're required
  for (const name of Object.keys(response.fields)) {
    const value = response.fields[name];
    output += `  <input name="${name}" value="${value}" type="hidden"/>\n`;
  }
  output += '  <input type="file" name="file"/><br />\n';
  output += '  <input type="submit" value="Upload File"/><br />\n';
  output += '</form>';

  console.log(output);
}

generateV4SignedPolicy().catch(console.error);

use Google\Cloud\Storage\StorageClient;

/**
 * Generates a v4 POST Policy to be used in an HTML form and echo's form.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 */
function generate_v4_post_policy(string $bucketName, string $objectName): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $response = $bucket->generateSignedPostPolicyV4(
        $objectName,
        new \DateTime('10 min'),
        [
            'fields' => [
                'x-goog-meta-test' => 'data'
            ]
        ]
    );

    $url = $response['url'];
    $output = "<form action='$url' method='POST' enctype='multipart/form-data'>" . PHP_EOL;
    foreach ($response['fields'] as $name => $value) {
        $output .= "  <input name='$name' value='$value' type='hidden'/>" . PHP_EOL;
    }
    $output .= "  <input type='file' name='file'/><br />" . PHP_EOL;
    $output .= "  <input type='submit' value='Upload File' name='submit'/><br />" . PHP_EOL;
    $output .= '</form>' . PHP_EOL;

    echo $output;
}

import datetime

from google.cloud import storage


def generate_signed_post_policy_v4(bucket_name, blob_name):
    """Generates a v4 POST Policy and prints an HTML form."""
    # bucket_name = 'your-bucket-name'
    # blob_name = 'your-object-name'

    storage_client = storage.Client()

    policy = storage_client.generate_signed_post_policy_v4(
        bucket_name,
        blob_name,
        expiration=datetime.timedelta(minutes=10),
        fields={
          'x-goog-meta-test': 'data'
        }
    )

    # Create an HTML form with the provided policy
    header = "<form action='{}' method='POST' enctype='multipart/form-data'>\n"
    form = header.format(policy["url"])

    # Include all fields returned in the HTML form as they're required
    for key, value in policy["fields"].items():
        form += f"  <input name='{key}' value='{value}' type='hidden'/>\n"

    form += "  <input type='file' name='file'/><br />\n"
    form += "  <input type='submit' value='Upload File' /><br />\n"
    form += "</form>"

    print(form)

    return form

def generate_signed_post_policy_v4 bucket_name:, file_name:
  # The ID of the GCS bucket to upload to
  # bucket_name = "your-unique-bucket-name"

  # The name to give the object uploaded to GCS
  # file_name = "your-file-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new

  bucket = storage.bucket bucket_name
  post_object = bucket.generate_signed_post_policy_v4 file_name,
                                                      expires: 600,
                                                      fields:  { "x-goog-meta-test" => "data" }

  html_form = "<form action='#{post_object.url}' method='POST' enctype='multipart/form-data'>\n"
  post_object.fields.each do |name, value|
    html_form += "  <input name='#{name}' value='#{value}' type='hidden'/>\n"
  end
  html_form += "  <input type='file' name='file'/><br />\n"
  html_form += "  <input type='submit' value='Upload File'/><br />\n"
  html_form += "</form>\n"

  puts "You can use the following form to upload an object to bucket #{bucket_name} for the next 10 minutes:\n"
  puts html_form

  post_object
end