Funciones de HTTP

Usa funciones de HTTP cuando desees invocar tu función mediante solicitudes HTTP(s). Para permitir la semántica de HTTP, las firmas de las funciones de HTTP aceptan argumentos específicos de HTTP.

Puedes configurar funciones de HTTP para que solo se puedan activar con HTTPS, como se describe en los Niveles de seguridad.

Ejecuta las muestras

Para ejecutar las muestras en este documento, asegúrate de haber configurado el entorno de ejecución como se describe en esta guía de inicio rápido. En especial, asegúrate de clonar el repositorio de muestra en tu máquina local para asegurarte de que todos los archivos necesarios estén presentes en tu entorno.

Ejemplo de uso

En el siguiente ejemplo, se muestra cómo procesar una solicitud HTTP POST que contiene un parámetro name:

Node.js

functions/helloworld/index.js 
const escapeHtml = require('escape-html');

/**
 * HTTP Cloud Function.
 *
 * @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.helloHttp = (req, res) => {
  res.send(`Hello ${escapeHtml(req.query.name || req.body.name || 'World')}!`);
};

Python

functions/helloworld/main.py 
from flask import escape

def hello_http(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>.
    """
    request_json = request.get_json(silent=True)
    request_args = request.args

    if request_json and 'name' in request_json:
        name = request_json['name']
    elif request_args and 'name' in request_args:
        name = request_args['name']
    else:
        name = 'World'
    return 'Hello {}!'.format(escape(name))

Go

functions/helloworld/hello_http.go 

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

import (
	"encoding/json"
	"fmt"
	"html"
	"net/http"
)

// HelloHTTP is an HTTP Cloud Function with a request parameter.
func HelloHTTP(w http.ResponseWriter, r *http.Request) {
	var d struct {
		Name string `json:"name"`
	}
	if err := json.NewDecoder(r.Body).Decode(&d); err != nil {
		fmt.Fprint(w, "Hello, World!")
		return
	}
	if d.Name == "" {
		fmt.Fprint(w, "Hello, World!")
		return
	}
	fmt.Fprintf(w, "Hello, %s!", html.EscapeString(d.Name))
}

Java

functions/helloworld/hello-http/src/main/java/functions/HelloHttp.java 

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.logging.Logger;

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

  private static final Gson gson = new Gson();

  @Override
  public void service(HttpRequest request, HttpResponse response)
      throws IOException {
    // Check URL parameters for "name" field
    // "world" is the default value
    String name = request.getFirstQueryParameter("name").orElse("world");

    // Parse JSON request and check for "name" field
    try {
      JsonElement requestParsed = gson.fromJson(request.getReader(), JsonElement.class);
      JsonObject requestJson = null;

      if (requestParsed != null && requestParsed.isJsonObject()) {
        requestJson = requestParsed.getAsJsonObject();
      }

      if (requestJson != null && requestJson.has("name")) {
        name = requestJson.get("name").getAsString();
      }
    } catch (JsonParseException e) {
      logger.severe("Error parsing JSON: " + e.getMessage());
    }

    var writer = new PrintWriter(response.getWriter());
    writer.printf("Hello %s!", name);
  }
}

C#

functions/helloworld/HelloHttp/Function.cs 
using Google.Cloud.Functions.Framework;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using System.IO;
using System.Text.Json;
using System.Threading.Tasks;

namespace HelloHttp
{
    public class Function : IHttpFunction
    {
        private readonly ILogger _logger;

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

        public async Task HandleAsync(HttpContext context)
        {
            HttpRequest request = context.Request;
            // Check URL parameters for "name" field
            // "world" is the default value
            string name = ((string) request.Query["name"]) ?? "world";

            // If there's a body, parse it as JSON and check for "name" field.
            using TextReader reader = new StreamReader(request.Body);
            string text = await reader.ReadToEndAsync();
            if (text.Length > 0)
            {
                try
                {
                    JsonElement json = JsonSerializer.Deserialize<JsonElement>(text);
                    if (json.TryGetProperty("name", out JsonElement nameElement) &&
                        nameElement.ValueKind == JsonValueKind.String)
                    {
                        name = nameElement.GetString();
                    }
                }
                catch (JsonException parseException)
                {
                    _logger.LogError(parseException, "Error parsing JSON request");
                }
            }

            await context.Response.WriteAsync($"Hello {name}!");
        }
    }
}

Ruby

functions/helloworld/http/app.rb 
require "functions_framework"
require "cgi"
require "json"

FunctionsFramework.http "hello_http" do |request|
  # The request parameter is a Rack::Request object.
  # See https://www.rubydoc.info/gems/rack/Rack/Request
  name = request.params["name"] ||
         (JSON.parse(request.body.read)["name"] rescue nil) ||
         "World"
  # Return the response body as a string.
  # You can also return a Rack::Response object, a Rack response array, or
  # a hash which will be JSON-encoded into a response.
  "Hello #{CGI.escape_html name}!"
end

PHP

functions/helloworld_http/index.php 

use Psr\Http\Message\ServerRequestInterface;

function helloHttp(ServerRequestInterface $request): string
{
    $name = 'World';
    $body = $request->getBody()->getContents();
    if (!empty($body)) {
        $json = json_decode($body, true);
        if (json_last_error() != JSON_ERROR_NONE) {
            throw new RuntimeException(sprintf(
                'Could not parse body: %s',
                json_last_error_msg()
            ));
        }
        $name = $json['name'] ?? $name;
    }
    $queryString = $request->getQueryParams();
    $name = $queryString['name'] ?? $name;

    return sprintf('Hello, %s!', htmlspecialchars($name));
}

Con el siguiente comando, se muestra cómo llamar a la función y pasarle un parámetro mediante curl:

curl -X POST HTTP_TRIGGER_ENDPOINT -H "Content-Type:application/json"  -d '{"name":"Jane"}'

En el comando anterior, HTTP_TRIGGER_ENDPOINT es la URL de la función, que se obtiene cuando esta se implementa. Para obtener más información, consulta Activadores de HTTP.

Pruébalo tú mismo

Si es la primera vez que usas Google Cloud, crea una cuenta para evaluar el rendimiento de Cloud Functions en situaciones reales. Los clientes nuevos también obtienen $300 en créditos gratuitos para ejecutar, probar y, además, implementar cargas de trabajo.

Probar Cloud Functions gratis

Niveles de seguridad

La función de nivel de seguridad controla si la URL de una función de HTTP es compatible solo con HTTPS o con HTTP y HTTPS. La compatibilidad con HTTP y HTTPS es la configuración predeterminada.

Cuando configuras funciones de HTTP para que solo puedan activarse con HTTPS, los usuarios que intenten usar el protocolo HTTP serán redireccionados.

Especifica el nivel de seguridad de una función de HTTP durante la implementación de la siguiente forma:

  • Si usas la herramienta de línea de comandos de gcloud para implementar tu función, puedes configurar el nivel de seguridad de la función con la marca --security-level. Sus valores posibles son secure-always o secure-optional, que corresponden al valor predeterminado. Por ejemplo:

    gcloud functions deploy FUNCTION_NAME --trigger-http --security-level=secure-always...

  • Si implementas tu función desde Cloud Console, usa la casilla de verificación Require HTTPS para que la función requiera HTTPS.

Si la función se puede activar con HTTP o HTTPS, el código de la función puede examinar el valor del encabezado de la solicitud X-Forwarded-Proto para determinar el protocolo que se utilizó. Una solicitud segura tendrá el valor https para ese encabezado, mientras que otras solicitudes tendrán el valor http.

Frameworks de HTTP

Para controlar HTTP, Cloud Functions utiliza una versión del framework de HTTP particular en cada entorno de ejecución:

Entorno de ejecución Framework de HTTP
Node.js Express 4.17.1
Python Flask 1.0.2
Go Interfaz http.HandlerFunc estándar
Java API de Functions Framework para Java
.NET API de Functions Framework para .NET
Ruby Functions Framework para Ruby
PHP Functions Framework for PHP

Finaliza funciones de HTTP

Si una función crea tareas en segundo plano (como subprocesos, futuros, objetos Promise de Node.js, devoluciones de llamada o procesos del sistema), debes finalizar o resolver estas tareas antes de que se muestre una respuesta HTTP. Cualquier tarea que no se finalice antes de una respuesta HTTP podría no completarse y también puede causar un comportamiento indefinido.

Analiza solicitudes HTTP

En el siguiente ejemplo, se muestra cómo leer las solicitudes HTTP en varios formatos:

Node.js

En Node.js, el cuerpo de la solicitud se analiza de forma automática según el encabezado content-type y se encuentra disponible mediante los argumentos de la función de HTTP.

functions/http/index.js 
const escapeHtml = require('escape-html');

/**
 * Responds to an HTTP request using data from the request body parsed according
 * to the "content-type" header.
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
exports.helloContent = (req, res) => {
  let name;

  switch (req.get('content-type')) {
    // '{"name":"John"}'
    case 'application/json':
      ({name} = req.body);
      break;

    // 'John', stored in a Buffer
    case 'application/octet-stream':
      name = req.body.toString(); // Convert buffer to a string
      break;

    // 'John'
    case 'text/plain':
      name = req.body;
      break;

    // 'name=John' in the body of a POST request (not the URL)
    case 'application/x-www-form-urlencoded':
      ({name} = req.body);
      break;
  }

  res.status(200).send(`Hello ${escapeHtml(name || 'World')}!`);
};

Python

functions/helloworld/main.py 
from flask import escape

def hello_content(request):
    """ Responds to an HTTP request using data from the request body parsed
    according to the "content-type" header.
    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>.
    """
    content_type = request.headers['content-type']
    if content_type == 'application/json':
        request_json = request.get_json(silent=True)
        if request_json and 'name' in request_json:
            name = request_json['name']
        else:
            raise ValueError("JSON is invalid, or missing a 'name' property")
    elif content_type == 'application/octet-stream':
        name = request.data
    elif content_type == 'text/plain':
        name = request.data
    elif content_type == 'application/x-www-form-urlencoded':
        name = request.form.get('name')
    else:
        raise ValueError("Unknown content type: {}".format(content_type))
    return 'Hello {}!'.format(escape(name))

Go

functions/http/http_content_type.go 

// Package http provides a set of HTTP Cloud Functions samples.
package http

import (
	"encoding/json"
	"fmt"
	"html"
	"io/ioutil"
	"log"
	"net/http"
)

// HelloContentType is an HTTP Cloud function.
// It uses the Content-Type header to identify the request payload format.
func HelloContentType(w http.ResponseWriter, r *http.Request) {
	var name string

	switch r.Header.Get("Content-Type") {
	case "application/json":
		var d struct {
			Name string `json:"name"`
		}
		err := json.NewDecoder(r.Body).Decode(&d)
		if err != nil {
			log.Printf("error parsing application/json: %v", err)
		} else {
			name = d.Name
		}
	case "application/octet-stream":
		body, err := ioutil.ReadAll(r.Body)
		if err != nil {
			log.Printf("error parsing application/octet-stream: %v", err)
		} else {
			name = string(body)
		}
	case "text/plain":
		body, err := ioutil.ReadAll(r.Body)
		if err != nil {
			log.Printf("error parsing text/plain: %v", err)
		} else {
			name = string(body)
		}
	case "application/x-www-form-urlencoded":
		if err := r.ParseForm(); err != nil {
			log.Printf("error parsing application/x-www-form-urlencoded: %v", err)
		} else {
			name = r.FormValue("name")
		}
	}

	if name == "" {
		name = "World"
	}

	fmt.Fprintf(w, "Hello, %s!", html.EscapeString(name))
}

Java

functions/http/parse-content-type/src/main/java/functions/ParseContentType.java 

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.Optional;

public class ParseContentType implements HttpFunction {

  // Use GSON (https://github.com/google/gson) to parse JSON content.
  private static final Gson gson = new Gson();

  // Responds to an HTTP request using data from the request body parsed according to the
  // "content-type" header.
  @Override
  public void service(HttpRequest request, HttpResponse response)
      throws IOException {
    String name = null;

    // Default values avoid null issues (with switch/case) and exceptions from get() (optionals)
    String contentType = request.getContentType().orElse("");

    switch (contentType) {
      case "application/json":
        // '{"name":"John"}'
        JsonObject body = gson.fromJson(request.getReader(), JsonObject.class);
        if (body.has("name")) {
          name = body.get("name").getAsString();
        }
        break;
      case "application/octet-stream":
        // 'John', stored in a Buffer
        name = new String(Base64.getDecoder().decode(request.getInputStream().readAllBytes()),
            StandardCharsets.UTF_8);
        break;
      case "text/plain":
        // 'John'
        name = request.getReader().readLine();
        break;
      case "application/x-www-form-urlencoded":
        // 'name=John' in the body of a POST request (not the URL)
        Optional<String> nameParam = request.getFirstQueryParameter("name");
        if (nameParam.isPresent()) {
          name = nameParam.get();
        }
        break;
      default:
        // Invalid or missing "Content-Type" header
        response.setStatusCode(HttpURLConnection.HTTP_UNSUPPORTED_TYPE);
        return;
    }

    // Verify that a name was provided
    if (name == null) {
      response.setStatusCode(HttpURLConnection.HTTP_BAD_REQUEST);
    }

    // Respond with a name
    var writer = new PrintWriter(response.getWriter());
    writer.printf("Hello %s!", name);
  }
}

C#

functions/http/ParseContentType/Function.cs 
using Google.Cloud.Functions.Framework;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Primitives;
using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Mime;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace ParseContentType
{
    public class Function : IHttpFunction
    {
        public async Task HandleAsync(HttpContext context)
        {
            HttpRequest request = context.Request;
            HttpResponse response = context.Response;

            string name = null;
            ContentType contentType = new ContentType(request.ContentType);

            switch (contentType.MediaType)
            {
                case "application/json":
                {
                    // '{"name":"John"}'
                    using TextReader reader = new StreamReader(request.Body);
                    string json = await reader.ReadToEndAsync();
                    JsonElement body = JsonSerializer.Deserialize<JsonElement>(json);
                    if (body.TryGetProperty("name", out JsonElement property) && property.ValueKind == JsonValueKind.String)
                    {
                        name = property.GetString();
                    }
                    break;
                }
                case "application/octet-stream":
                {
                    // 'John', encoded to bytes using UTF-8, then encoded as base64
                    using TextReader reader = new StreamReader(request.Body);
                    string base64 = await reader.ReadToEndAsync();
                    byte[] data = Convert.FromBase64String(base64);
                    name = Encoding.UTF8.GetString(data);
                    break;
                }
                case "text/plain":
                {
                    // 'John'
                    using TextReader reader = new StreamReader(request.Body);
                    name = await reader.ReadLineAsync();
                    break;
                }
                case "application/x-www-form-urlencoded":
                {
                    // 'name=John' in the body of a POST request (not the URL)
                    if (request.Form.TryGetValue("name", out StringValues value))
                    {
                        name = value;
                    }
                    break;
                }
            }
            if (name is object)
            {
                await response.WriteAsync($"Hello {name}!");
            }
            else
            {
                // Unrecognized content type, or the name wasn't in the content
                // (e.g. JSON without a "name" property)
                response.StatusCode = (int) HttpStatusCode.BadRequest;
            }
        }
    }
}

Ruby

functions/http/content/app.rb 
require "functions_framework"
require "json"

FunctionsFramework.http "http_content" do |request|
  # The request parameter is a Rack::Request object.
  # See https://www.rubydoc.info/gems/rack/Rack/Request
  content_type = request.content_type
  case content_type
  # '{"name":"John"}'
  when "application/json"
    name = (JSON.parse(request.body.read.to_s)["name"] rescue nil)
  # "John", stored in a Buffer
  when "application/octet-stream"
    name = request.body.read.to_s # Convert buffer to a string
  # "John"
  when "text/plain"
    name = request.body.read.to_s
  # "name=John" in the body of a POST request (not the URL)
  when "application/x-www-form-urlencoded"
    name = (request.params["name"] rescue nil)
  end

  name ||= "World"

  # Return the response body as a string.
  # You can also return a Rack::Response object, a Rack response array, or
  # a hash which will be JSON-encoded into a response.
  "Hello #{name}!"
end

PHP

functions/http_content_type/index.php 

use Psr\Http\Message\ServerRequestInterface;

function helloContent(ServerRequestInterface $request): string
{
    $name = 'World';
    $body = $request->getBody()->getContents();
    switch ($request->getHeaderLine('content-type')) {
        // '{"name":"John"}'
        case 'application/json':
          if (!empty($body)) {
              $json = json_decode($body, true);
              if (json_last_error() != JSON_ERROR_NONE) {
                  throw new RuntimeException(sprintf(
                      'Could not parse body: %s',
                      json_last_error_msg()
                  ));
              }
              $name = $json['name'] ?? $name;
          }
          break;
        // 'John', stored in a stream
        case 'application/octet-stream':
          $name = $body;
          break;
        // 'John'
        case 'text/plain':
          $name = $body;
          break;
        // 'name=John' in the body of a POST request (not the URL)
        case 'application/x-www-form-urlencoded':
          parse_str($body, $data);
          $name = $data['name'] ?? $name;
          break;
    }

    return sprintf('Hello %s!', htmlspecialchars($name));
}

Administra solicitudes de CORS

El uso compartido de recursos multiorigen (CORS) es una forma de permitir que las aplicaciones que se ejecutan en un dominio accedan al contenido de otro dominio, por ejemplo, cuando yourdomain.com realiza solicitudes a region-project.cloudfunctions.net/yourfunction.

Si CORS no está configurado correctamente, es probable que recibas errores similares a los siguientes:

XMLHttpRequest cannot load https://region-project.cloudfunctions.net/function.
No 'Access-Control-Allow-Origin' header is present on the requested resource.
Origin 'http://yourdomain.com' is therefore not allowed access.

Solicitud de comprobación previa

CORS consiste en dos solicitudes:

  • Una solicitud de comprobación previa de OPTIONS
  • Una solicitud principal que sigue a la solicitud de OPTIONS

La solicitud de comprobación previa contiene encabezados que indican qué método (Access-Control-Request-Method) y qué encabezados adicionales (Access-Control-Request-Headers) se enviarán en la solicitud principal, así como el origen de la solicitud principal (Origin).

Para administrar una solicitud de comprobación previa, debes establecer los encabezados Access-Control-Allow-* apropiados a fin de que coincidan con las solicitudes que deseas aceptar:

Node.js

functions/http/index.js 
/**
 * HTTP function that supports CORS requests.
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
exports.corsEnabledFunction = (req, res) => {
  // Set CORS headers for preflight requests
  // Allows GETs from any origin with the Content-Type header
  // and caches preflight response for 3600s

  res.set('Access-Control-Allow-Origin', '*');

  if (req.method === 'OPTIONS') {
    // Send response to OPTIONS requests
    res.set('Access-Control-Allow-Methods', 'GET');
    res.set('Access-Control-Allow-Headers', 'Content-Type');
    res.set('Access-Control-Max-Age', '3600');
    res.status(204).send('');
  } else {
    res.send('Hello World!');
  }
};

Python

functions/http/main.py 
def cors_enabled_function(request):
    # For more information about CORS and CORS preflight requests, see:
    # https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request

    # Set CORS headers for the preflight request
    if request.method == 'OPTIONS':
        # Allows GET requests from any origin with the Content-Type
        # header and caches preflight response for an 3600s
        headers = {
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'GET',
            'Access-Control-Allow-Headers': 'Content-Type',
            'Access-Control-Max-Age': '3600'
        }

        return ('', 204, headers)

    # Set CORS headers for the main request
    headers = {
        'Access-Control-Allow-Origin': '*'
    }

    return ('Hello World!', 200, headers)

Go

functions/http/cors.go 

// Package http provides a set of HTTP Cloud Functions samples.
package http

import (
	"fmt"
	"net/http"
)

// CORSEnabledFunction is an example of setting CORS headers.
// For more information about CORS and CORS preflight requests, see
// https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request.
func CORSEnabledFunction(w http.ResponseWriter, r *http.Request) {
	// Set CORS headers for the preflight request
	if r.Method == http.MethodOptions {
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "POST")
		w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
		w.Header().Set("Access-Control-Max-Age", "3600")
		w.WriteHeader(http.StatusNoContent)
		return
	}
	// Set CORS headers for the main request.
	w.Header().Set("Access-Control-Allow-Origin", "*")
	fmt.Fprint(w, "Hello, World!")
}

Java

functions/http/cors-enabled/src/main/java/functions/CorsEnabled.java 

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;
import java.net.HttpURLConnection;

public class CorsEnabled implements HttpFunction {
  // corsEnabled is an example of setting CORS headers.
  // For more information about CORS and CORS preflight requests, see
  // https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request.
  @Override
  public void service(HttpRequest request, HttpResponse response)
      throws IOException {
    // Set CORS headers
    //   Allows GETs from any origin with the Content-Type
    //   header and caches preflight response for 3600s
    response.appendHeader("Access-Control-Allow-Origin", "*");

    if ("OPTIONS".equals(request.getMethod())) {
      response.appendHeader("Access-Control-Allow-Methods", "GET");
      response.appendHeader("Access-Control-Allow-Headers", "Content-Type");
      response.appendHeader("Access-Control-Max-Age", "3600");
      response.setStatusCode(HttpURLConnection.HTTP_NO_CONTENT);
      return;
    }

    // Handle the main request.
    BufferedWriter writer = response.getWriter();
    writer.write("CORS headers set successfully!");
  }
}

C#

functions/http/Cors/Function.cs 
using Google.Cloud.Functions.Framework;
using Microsoft.AspNetCore.Http;
using System.Net;
using System.Threading.Tasks;

namespace Cors
{
    // For more information about CORS and CORS preflight requests, see
    // https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request.
    public class Function : IHttpFunction
    {
        public async Task HandleAsync(HttpContext context)
        {
            HttpRequest request = context.Request;
            HttpResponse response = context.Response;

            // Set CORS headers
            //   Allows GETs from any origin with the Content-Type
            //   header and caches preflight response for 3600s

            response.Headers.Append("Access-Control-Allow-Origin", "*");
            if (HttpMethods.IsOptions(request.Method))
            {
                response.Headers.Append("Access-Control-Allow-Methods", "GET");
                response.Headers.Append("Access-Control-Allow-Headers", "Content-Type");
                response.Headers.Append("Access-Control-Max-Age", "3600");
                response.StatusCode = (int) HttpStatusCode.NoContent;
                return;
            }

            await response.WriteAsync("CORS headers set successfully!");
        }
    }
}

Ruby

functions/http/cors/app.rb 
FunctionsFramework.http "cors_enabled_function" do |request|
  # For more information about CORS and CORS preflight requests, see
  # https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request
  # for more information.

  # Set CORS headers for the preflight request
  if request.options?
    # Allows GET requests from any origin with the Content-Type
    # header and caches preflight response for an 3600s
    headers = {
      "Access-Control-Allow-Origin"  => "*",
      "Access-Control-Allow-Methods" => "GET",
      "Access-Control-Allow-Headers" => "Content-Type",
      "Access-Control-Max-Age"       => "3600"
    }
    [204, headers, []]
  else
    # Set CORS headers for the main request
    headers = {
      "Access-Control-Allow-Origin" => "*"
    }

    [200, headers, ["Hello World!"]]
  end
end

PHP

functions/http_cors/index.php 

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use GuzzleHttp\Psr7\Response;

function corsEnabledFunction(ServerRequestInterface $request): ResponseInterface
{
    // Set CORS headers for preflight requests
    // Allows GETs from any origin with the Content-Type header
    // and caches preflight response for 3600s
    $headers = ['Access-Control-Allow-Origin' => '*'];

    if ($request->getMethod() === 'OPTIONS') {
        // Send response to OPTIONS requests
        $headers = array_merge($headers, [
            'Access-Control-Allow-Methods' => 'GET',
            'Access-Control-Allow-Headers' => 'Content-Type',
            'Access-Control-Max-Age' => '3600'
        ]);
        return new Response(204, $headers, '');
    } else {
        return new Response(200, $headers, 'Hello World!');
    }
}

De manera alternativa, puedes usar una biblioteca de terceros para que administre CORS por ti.

Limitaciones

Las solicitudes de comprobación previa de CORS se envían sin un encabezado de Authorization, por lo que se rechazarán en todas las funciones de HTTP no públicas. Como las solicitudes de verificación previa fallan, la solicitud principal también lo hará.

Las funciones de HTTP requieren autenticación de forma predeterminada, por lo que estas son las opciones para evitar esta limitación:

Aloja en el mismo dominio

En lugar de implementar CORS, podrías alojar tu sitio web y tus funciones en el mismo dominio. Puesto que las solicitudes ahora provendrían del mismo origen, CORS no se aplicará. Esta acción simplifica tu código de manera considerable.

La manera más sencilla de hacerlo es integrar Firebase Hosting a Google Cloud Functions.

Cómo usar Cloud Endpoints para controlar CORS

Puedes implementar un proxy de Cloud Endpoints y habilitar CORS.

Si deseas contar con capacidades de autenticación, también puedes habilitar la validación del token de ID de Google, lo que validará estos mismos tokens de autenticación.

Cómo controlar métodos de HTTP

Las funciones de HTTP aceptan todos los métodos de HTTP. En el siguiente ejemplo, se muestra cómo realizar diferentes acciones según el método de HTTP recibido (por ejemplo, GET y PUT):

Node.js

functions/http/index.js 
/**
 * Responds to a GET request with "Hello World!". Forbids a PUT request.
 *
 * @example
 * gcloud functions call helloHttp
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
exports.helloHttp = (req, res) => {
  switch (req.method) {
    case 'GET':
      res.status(200).send('Hello World!');
      break;
    case 'PUT':
      res.status(403).send('Forbidden!');
      break;
    default:
      res.status(405).send({error: 'Something blew up!'});
      break;
  }
};

Python

functions/helloworld/main.py 
def hello_method(request):
    """ Responds to a GET request with "Hello world!". Forbids a PUT request.
    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>.
    """
    from flask import abort

    if request.method == 'GET':
        return 'Hello World!'
    elif request.method == 'PUT':
        return abort(403)
    else:
        return abort(405)

Go

functions/http/http_request_method.go 

// Package http provides a set of HTTP Cloud Functions samples.
package http

import (
	"fmt"
	"net/http"
)

// HelloHTTPMethod is an HTTP Cloud function.
// It uses the request method to differentiate the response.
func HelloHTTPMethod(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		fmt.Fprint(w, "Hello World!")
	case http.MethodPut:
		http.Error(w, "403 - Forbidden", http.StatusForbidden)
	default:
		http.Error(w, "405 - Method Not Allowed", http.StatusMethodNotAllowed)
	}
}

Java

functions/http/http-method/src/main/java/functions/HttpMethod.java 

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;
import java.net.HttpURLConnection;

public class HttpMethod implements HttpFunction {
  @Override
  public void service(HttpRequest request, HttpResponse response)
      throws IOException {

    BufferedWriter writer = response.getWriter();

    switch (request.getMethod()) {
      case "GET":
        response.setStatusCode(HttpURLConnection.HTTP_OK);
        writer.write("Hello world!");
        break;
      case "PUT":
        response.setStatusCode(HttpURLConnection.HTTP_FORBIDDEN);
        writer.write("Forbidden!");
        break;
      default:
        response.setStatusCode(HttpURLConnection.HTTP_BAD_METHOD);
        writer.write("Something blew up!");
        break;
    }
  }
}

C#

functions/http/HttpRequestMethod/Function.cs 
using Google.Cloud.Functions.Framework;
using Microsoft.AspNetCore.Http;
using System.Net;
using System.Threading.Tasks;

namespace HttpRequestMethod
{
    public class Function : IHttpFunction
    {
        public async Task HandleAsync(HttpContext context)
        {
            HttpResponse response = context.Response;
            switch (context.Request.Method)
            {
                case "GET":
                    response.StatusCode = (int) HttpStatusCode.OK;
                    await response.WriteAsync("Hello world!");
                    break;
                case "PUT":
                    response.StatusCode = (int) HttpStatusCode.Forbidden;
                    await response.WriteAsync("Forbidden!");
                    break;
                default:
                    response.StatusCode = (int) HttpStatusCode.MethodNotAllowed;
                    await response.WriteAsync("Something blew up!");
                    break;
            }
        }
    }
}

Ruby

functions/http/method/app.rb 
require "functions_framework"
require "json"

FunctionsFramework.http "http_method" do |request|
  # The request parameter is a Rack::Request object.
  # See https://www.rubydoc.info/gems/rack/Rack/Request
  case request.request_method
  when "GET"
    status = 200
    body = "Hello World!"
  when "PUT"
    status = 403
    body = "Forbidden!"
  else
    status = 405
    body = '{"error":"Something blew up!"}'
  end

  # Return the response body as a Rack::Response object.
  ::Rack::Response.new body, status
end

PHP

functions/http_method/index.php 

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use GuzzleHttp\Psr7\Response;

function httpMethod(ServerRequestInterface $request): ResponseInterface
{
    switch ($request->getMethod()) {
        case 'GET':
            // Example: read request
            return new Response(
                200, // OK
                [],
                'Hello, World!' . PHP_EOL
            );
            break;
        case 'PUT':
            // Example: write request to a read-only resource
            return new Response(
                403, // Permission denied
                [],
                'Forbidden!' . PHP_EOL
            );
            break;
        default:
            // Example: request type not supported by the application
            $json_payload = json_encode([
                'error' => 'something blew up!'
            ]);
            return new Response(
                405, // Method not allowed
                ['Content-Type' => 'application/json'],
                $json_payload
            );
            break;
    }
}

Administra tipos de contenido

Para Node.js, Cloud Functions analiza los tipos de contenido del cuerpo de la solicitud de application/json y application/x-www-form-urlencoded como se muestra arriba. Los tipos de contenido de texto sin formato (text/plain) se pasan como strings con UTF-8 como codificación predeterminada (o una codificación personalizada proporcionada en el encabezado content-type).

Se puede acceder a otros tipos de contenido mediante la inspección del argumento de tu función de HTTP. Los métodos para hacerlo varían según el lenguaje.

En el siguiente ejemplo, se maneja una solicitud con un tipo de contenido de text/xml:

Node.js

La propiedad rawBody contiene bytes sin analizar del cuerpo de la solicitud.

functions/http/index.js 
/**
 * Parses a document of type 'text/xml'
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
exports.parseXML = (req, res) => {
  // Convert the request to a Buffer and a string
  // Use whichever one is accepted by your XML parser
  const data = req.rawBody;
  const xmlData = data.toString();

  const {parseString} = require('xml2js');

  parseString(xmlData, (err, result) => {
    if (err) {
      console.error(err);
      res.status(500).end();
      return;
    }
    res.send(result);
  });
};

Python

functions/http/main.py 
import json
import xmltodict

def parse_xml(request):
    """ Parses a document of type 'text/xml'
    Args:
        request (flask.Request): The request object.
    Returns:
        The response text, or any set of values that can be turned into a
         Response object using `make_response`
        <http://flask.pocoo.org/docs/1.0/api/#flask.Flask.make_response>.
    """
    data = xmltodict.parse(request.data)
    return json.dumps(data, indent=2)

Go

functions/http/xml.go 

// Package http provides a set of HTTP Cloud Functions samples.
package http

import (
	"encoding/xml"
	"fmt"
	"html"
	"io/ioutil"
	"net/http"
)

// ParseXML is an example of parsing a text/xml request.
func ParseXML(w http.ResponseWriter, r *http.Request) {
	var d struct {
		Name string
	}
	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "Could not read request", http.StatusBadRequest)
	}
	if err := xml.Unmarshal(b, &d); err != nil {
		http.Error(w, "Could not parse request", http.StatusBadRequest)
	}
	if d.Name == "" {
		d.Name = "World"
	}
	fmt.Fprintf(w, "Hello, %v!", html.EscapeString(d.Name))
}

Datos multiparte

En el siguiente ejemplo, se muestra cómo procesar datos con un tipo de contenido multipart/form-data. Según el lenguaje que hayas elegido, es posible que debas usar una biblioteca de análisis.

Node.js

functions/http/index.js 
/**
 * Parses a 'multipart/form-data' upload request
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
const path = require('path');
const os = require('os');
const fs = require('fs');

// Node.js doesn't have a built-in multipart/form-data parsing library.
// Instead, we can use the 'busboy' library from NPM to parse these requests.
const Busboy = require('busboy');

exports.uploadFile = (req, res) => {
  if (req.method !== 'POST') {
    // Return a "method not allowed" error
    return res.status(405).end();
  }
  const busboy = new Busboy({headers: req.headers});
  const tmpdir = os.tmpdir();

  // This object will accumulate all the fields, keyed by their name
  const fields = {};

  // This object will accumulate all the uploaded files, keyed by their name.
  const uploads = {};

  // This code will process each non-file field in the form.
  busboy.on('field', (fieldname, val) => {
    /**
     *  TODO(developer): Process submitted field values here
     */
    console.log(`Processed field ${fieldname}: ${val}.`);
    fields[fieldname] = val;
  });

  const fileWrites = [];

  // This code will process each file uploaded.
  busboy.on('file', (fieldname, file, filename) => {
    // Note: os.tmpdir() points to an in-memory file system on GCF
    // Thus, any files in it must fit in the instance's memory.
    console.log(`Processed file ${filename}`);
    const filepath = path.join(tmpdir, filename);
    uploads[fieldname] = filepath;

    const writeStream = fs.createWriteStream(filepath);
    file.pipe(writeStream);

    // File was processed by Busboy; wait for it to be written.
    // Note: GCF may not persist saved files across invocations.
    // Persistent files must be kept in other locations
    // (such as Cloud Storage buckets).
    const promise = new Promise((resolve, reject) => {
      file.on('end', () => {
        writeStream.end();
      });
      writeStream.on('finish', resolve);
      writeStream.on('error', reject);
    });
    fileWrites.push(promise);
  });

  // Triggered once all uploaded files are processed by Busboy.
  // We still need to wait for the disk writes (saves) to complete.
  busboy.on('finish', async () => {
    await Promise.all(fileWrites);

    /**
     * TODO(developer): Process saved files here
     */
    for (const file in uploads) {
      fs.unlinkSync(uploads[file]);
    }
    res.send();
  });

  busboy.end(req.rawBody);
};

Python

functions/http/main.py 
import os
import tempfile
from werkzeug.utils import secure_filename

# Helper function that computes the filepath to save files to
def get_file_path(filename):
    # Note: tempfile.gettempdir() points to an in-memory file system
    # on GCF. Thus, any files in it must fit in the instance's memory.
    file_name = secure_filename(filename)
    return os.path.join(tempfile.gettempdir(), file_name)

def parse_multipart(request):
    """ Parses a 'multipart/form-data' upload request
    Args:
        request (flask.Request): The request object.
    Returns:
        The response text, or any set of values that can be turned into a
         Response object using `make_response`
        <http://flask.pocoo.org/docs/1.0/api/#flask.Flask.make_response>.
    """

    # This code will process each non-file field in the form
    fields = {}
    data = request.form.to_dict()
    for field in data:
        fields[field] = data[field]
        print('Processed field: %s' % field)

    # This code will process each file uploaded
    files = request.files.to_dict()
    for file_name, file in files.items():
        # Note: GCF may not keep files saved locally between invocations.
        # If you want to preserve the uploaded files, you should save them
        # to another location (such as a Cloud Storage bucket).
        file.save(get_file_path(file_name))
        print('Processed file: %s' % file_name)

    # Clear temporary directory
    for file_name in files:
        file_path = get_file_path(file_name)
        os.remove(file_path)

    return "Done!"

Go

functions/http/form.go 

// Package http provides a set of HTTP Cloud Functions samples.
package http

import (
	"fmt"
	"log"
	"net/http"
)

// UploadFile processes a 'multipart/form-data' upload request.
func UploadFile(w http.ResponseWriter, r *http.Request) {
	const maxMemory = 2 * 1024 * 1024 // 2 megabytes.

	// ParseMultipartForm parses a request body as multipart/form-data.
	// The whole request body is parsed and up to a total of maxMemory bytes of
	// its file parts are stored in memory, with the remainder stored on
	// disk in temporary files.

	// Note that any files saved during a particular invocation may not
	// persist after the current invocation completes; persistent files
	// should be stored elsewhere, such as in a Cloud Storage bucket.
	if err := r.ParseMultipartForm(maxMemory); err != nil {
		http.Error(w, "Unable to parse form", http.StatusBadRequest)
		log.Printf("Error parsing form: %v", err)
		return
	}

	// Be sure to remove all temporary files after your function is finished.
	defer func() {
		if err := r.MultipartForm.RemoveAll(); err != nil {
			http.Error(w, "Error cleaning up form files", http.StatusInternalServerError)
			log.Printf("Error cleaning up form files: %v", err)
		}
	}()

	// r.MultipartForm.File contains *multipart.FileHeader values for every
	// file in the form. You can access the file contents using
	// *multipart.FileHeader's Open method.
	for _, headers := range r.MultipartForm.File {
		for _, h := range headers {
			fmt.Fprintf(w, "File uploaded: %q (%v bytes)", h.Filename, h.Size)
			// Use h.Open() to read the contents of the file.
		}
	}

}

Java

functions/http/http-form-data/src/main/java/functions/HttpFormData.java 

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.logging.Logger;

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

  @Override
  public void service(HttpRequest request, HttpResponse response)
      throws IOException {

    if (!"POST".equals(request.getMethod())) {
      response.setStatusCode(HttpURLConnection.HTTP_BAD_METHOD);
      return;
    }

    // This code will process each file uploaded.
    String tempDirectory = System.getProperty("java.io.tmpdir");
    for (HttpRequest.HttpPart httpPart : request.getParts().values()) {
      String filename = httpPart.getFileName().orElse(null);
      if (filename == null) {
        continue;
      }

      logger.info("Processed file: " + filename);

      // Note: GCF's temp directory is an in-memory file system
      // Thus, any files in it must fit in the instance's memory.
      Path filePath = Paths.get(tempDirectory, filename).toAbsolutePath();

      // Note: files saved to a GCF instance itself may not persist across executions.
      // Persistent files should be stored elsewhere, e.g. a Cloud Storage bucket.
      Files.copy(httpPart.getInputStream(), filePath, StandardCopyOption.REPLACE_EXISTING);

      // TODO(developer): process saved files here
      Files.delete(filePath);
    }

    // This code will process other form fields.
    request.getQueryParameters().forEach(
        (fieldName, fieldValues) -> {
          String firstFieldValue = fieldValues.get(0);

          // TODO(developer): process field values here
          logger.info(String.format(
              "Processed field: %s (value: %s)", fieldName, firstFieldValue));
        });
  }
}

C#

functions/http/HttpFormData/Function.cs 
using Google.Cloud.Functions.Framework;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Primitives;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Threading.Tasks;

namespace HttpFormData
{
    public class Function : IHttpFunction
    {
        private readonly ILogger _logger;

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

        public async Task HandleAsync(HttpContext context)
        {
            HttpResponse response = context.Response;
            HttpRequest request = context.Request;

            if (request.Method != "POST")
            {
                response.StatusCode = (int) HttpStatusCode.MethodNotAllowed;
                return;
            }

            // This code will process each file uploaded.
            string tempDirectory = Path.GetTempPath();
            foreach (IFormFile file in request.Form.Files)
            {
                if (string.IsNullOrEmpty(file.FileName))
                {
                    continue;
                }
                _logger.LogInformation("Processed file: {file}", file.FileName);

                // Note: GCF's temp directory is an in-memory file system
                // Thus, any files in it must fit in the instance's memory.
                string outputPath = Path.Combine(tempDirectory, file.FileName);

                // Note: files saved to a GCF instance itself may not persist across executions.
                // Persistent files should be stored elsewhere, e.g. a Cloud Storage bucket.
                using (FileStream output = File.Create(outputPath))
                {
                    await file.CopyToAsync(output);
                }

                // TODO(developer): process saved files here
                File.Delete(outputPath);
            }

            // This code will process other form fields.
            foreach (KeyValuePair<string, StringValues> parameter in request.Form)
            {
                // TODO(developer): process field values here
                _logger.LogInformation("Processed field '{key}' (value: '{value}')",
                    parameter.Key, (string) parameter.Value);
            }
        }
    }
}

Ruby

functions/http/form_data/app.rb 
require "functions_framework"

FunctionsFramework.http "http_form_data" do |request|
  # The request parameter is a Rack::Request object.
  # See https://www.rubydoc.info/gems/rack/Rack/Request

  # This Rack call parses multipart form data, returning the params as a hash.
  # The returned params hash includes an entry for each field. File uploads
  # are written to Tempfiles and represented by hashes, while plain fields are
  # represented by strings.
  params = request.POST

  begin
    params.each do |name, part|
      if part.is_a? Hash
        # Handle a file upload part by logging the md5 hash.
        md5 = Digest::MD5.hexdigest part[:tempfile].read
        file_name = part[:filename]
        logger.info "Processed file=#{file_name} md5=#{md5}"
      else
        # Handle a non-file part by logging the value.
        logger.info "Processed field=#{name} value=#{part}"
      end
    end
  ensure
    # Ensure that all Tempfile objects are closed and deleted. The Cloud
    # Functions runtime keeps temporary files in an in-memory file system,
    # so to lower memory usage it is good practice to clean up Tempfiles
    # explicitly rather than wait for object finalization.
    params.each_value do |part|
      part[:tempfile].close! if part.is_a? Hash
    end
  end

  # The HTTP response body.
  "OK"
end

PHP

functions/http_form_data/index.php 

use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Message\ResponseInterface;
use GuzzleHttp\Psr7\Response;

function uploadFile(ServerRequestInterface $request): ResponseInterface
{
    if ($request->getMethod() != 'POST') {
        return new Response(405, [], 'Method Not Allowed: expected POST, found ' . $request->getMethod());
    }

    $contentType = $request->getHeader('Content-Type')[0];
    if (strpos($contentType, 'multipart/form-data') !== 0) {
        return new Response(400, [], 'Bad Request: content of type "multipart/form-data" not provided, found ' . $contentType);
    }

    $fileList = [];
    /** @var $file Psr\Http\Message\UploadedFileInterface */
    foreach ($request->getUploadedFiles() as $name => $file) {
        // Use caution when trusting the client-provided filename:
        // https://owasp.org/www-community/vulnerabilities/Unrestricted_File_Upload
        $fileList[] = $file->getClientFilename();

        infoLog('Processing ' . $file->getClientFilename());
        $filename = tempnam(sys_get_temp_dir(), $name . '.') . '-' . $file->getClientFilename();

        // Use $file->getStream() to process the file contents in ways other than a direct "file save".
        infoLog('Saving to ' . $filename);
        $file->moveTo($filename);
    }

    if (empty($fileList)) {
        $msg = 'Bad Request: no files sent for upload';
        errorLog($msg);
        return new Response(400, [], $msg);
    }

    return new Response(201, [], 'Saved ' . join(', ', $fileList));
}

function errorLog($msg): void
{
    $stream = fopen('php://stderr', 'wb');
    $entry = json_encode(['msg' => $msg, 'severity' => 'error'], JSON_UNESCAPED_UNICODE|JSON_UNESCAPED_SLASHES);
    fwrite($stream, $entry . PHP_EOL);
}

function infoLog($msg): void
{
    $stream = fopen('php://stderr', 'wb');
    $entry = json_encode(['message' => $msg, 'severity' => 'info'], JSON_UNESCAPED_UNICODE|JSON_UNESCAPED_SLASHES);
    fwrite($stream, $entry . PHP_EOL);
}

Sube archivos a través de Cloud Storage

Un caso práctico común de Cloud Functions es el procesamiento de archivos. Para archivos grandes o aquellos que requieren un almacenamiento continuo más allá del alcance de una sola solicitud, puedes usar Cloud Storage como un punto de entrada para tus cargas de archivos. Para lograrlo, debes generar una URL firmada que proporcione acceso de escritura temporal al bucket de Cloud Storage.

Si usas Cloud Functions directamente, genera una URL firmada con la biblioteca de cliente de Cloud Storage.

El proceso para subir archivos a una función de Cloud Functions con Cloud Storage consta de tres pasos que se describen a continuación:

  1. Los clientes llaman a una función de Cloud Functions directamente para recuperar la URL firmada.

  2. Luego, los clientes envían los datos del archivo a la URL firmada a través de la solicitud HTTP PUT.

  3. Se activa una segunda función de Cloud Functions mediante la mutación en el bucket de Storage para procesar aún más el archivo.

Puedes ver el siguiente ejemplo de uso de la biblioteca cliente de Cloud Storage para generar una URL firmada.

Cloud Functions tiene una “credencial de aplicación predeterminada” que, por lo general, no incluye el permiso iam.serviceAccounts.signBlob. Para habilitar este permiso, primero será necesario que te asegures de que la cuenta de servicio de tu función tenga la función de IAM apropiada. Puedes hacer esto con Cloud Console o la herramienta de línea de comandos de gcloud:

Console

Para asegurarte de que la cuenta de servicio de tu función tenga la función de IAM apropiada, puedes modificar directamente las funciones de IAM de una cuenta si sigues estos pasos:

  1. Ve a Google Cloud Console:

    Ir a Google Cloud Console

  2. Selecciona la cuenta correcta y elige Editor > Cuentas de servicio > Creador de token de cuenta de servicio.

gcloud

Para asegurarte de que la cuenta de servicio de la función tiene la función apropiada, ejecuta el siguiente comando. La función predefinida serviceAccountTokenCreator tiene el permiso iam.serviceAccounts.signBlob que necesitas:

gcloud projects add-iam-policy-binding YOUR_PROJECT \
--member serviceAccount:YOUR_SERVICE_ACCOUNT --role roles/iam.serviceAccountTokenCreator

Puedes determinar qué cuenta de servicio usan tus funciones mediante Cloud Console o la herramienta de línea de comandos de gcloud:

Console

Sigue estos pasos para determinar la cuenta de servicio que usan tus funciones con Cloud Console:

  1. Ve a Google Cloud Console:

    Ir a Google Cloud Console

  2. En la lista, selecciona la función que quieres inspeccionar.

Puedes ver la cuenta de servicio en la página de detalles de la función.

gcloud

Para determinar la cuenta de servicio que usan tus funciones, ejecuta el siguiente comando y busca la propiedad serviceAccountEmail:

gcloud beta functions describe YOUR_FUNCTION_NAME

A continuación, se muestra un ejemplo de cómo generar una URL firmada:

Node.js

samples/generateV4UploadSignedUrl.js 
/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The full path of your file inside the GCS bucket, e.g. 'yourFile.jpg' or 'folder1/folder2/yourFile.jpg'
// 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 generateV4UploadSignedUrl() {
  // These options will allow temporary uploading of the file with outgoing
  // Content-Type: application/octet-stream header.
  const options = {
    version: 'v4',
    action: 'write',
    expires: Date.now() + 15 * 60 * 1000, // 15 minutes
    contentType: 'application/octet-stream',
  };

  // Get a v4 signed URL for uploading file
  const [url] = await storage
    .bucket(bucketName)
    .file(fileName)
    .getSignedUrl(options);

  console.log('Generated PUT signed URL:');
  console.log(url);
  console.log('You can use this URL with any user agent, for example:');
  console.log(
    "curl -X PUT -H 'Content-Type: application/octet-stream' " +
      `--upload-file my-file '${url}'`
  );
}

generateV4UploadSignedUrl().catch(console.error);

Python

storage/cloud-client/storage_generate_upload_signed_url_v4.py 
import datetime

from google.cloud import storage

def generate_upload_signed_url_v4(bucket_name, blob_name):
    """Generates a v4 signed URL for uploading a blob using HTTP PUT.

    Note that this method requires a service account key file. You can not use
    this if you are using Application Default Credentials from Google Compute
    Engine or from the Google Cloud SDK.
    """
    # bucket_name = 'your-bucket-name'
    # blob_name = 'your-object-name'

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(blob_name)

    url = blob.generate_signed_url(
        version="v4",
        # This URL is valid for 15 minutes
        expiration=datetime.timedelta(minutes=15),
        # Allow PUT requests using this URL.
        method="PUT",
        content_type="application/octet-stream",
    )

    print("Generated PUT signed URL:")
    print(url)
    print("You can use this URL with any user agent, for example:")
    print(
        "curl -X PUT -H 'Content-Type: application/octet-stream' "
        "--upload-file my-file '{}'".format(url)
    )
    return url

Go

storage/objects/generate_v4_put_object_signed_url.go 
import (
	"fmt"
	"io"
	"io/ioutil"
	"time"

	"cloud.google.com/go/storage"
	"golang.org/x/oauth2/google"
)

// generateV4PutObjectSignedURL generates object signed URL with PUT method.
func generateV4PutObjectSignedURL(w io.Writer, bucket, object, serviceAccount string) (string, error) {
	// bucket := "bucket-name"
	// object := "object-name"
	// serviceAccount := "service_account.json"
	jsonKey, err := ioutil.ReadFile(serviceAccount)
	if err != nil {
		return "", fmt.Errorf("ioutil.ReadFile: %v", err)
	}
	conf, err := google.JWTConfigFromJSON(jsonKey)
	if err != nil {
		return "", fmt.Errorf("google.JWTConfigFromJSON: %v", err)
	}
	opts := &storage.SignedURLOptions{
		Scheme: storage.SigningSchemeV4,
		Method: "PUT",
		Headers: []string{
			"Content-Type:application/octet-stream",
		},
		GoogleAccessID: conf.Email,
		PrivateKey:     conf.PrivateKey,
		Expires:        time.Now().Add(15 * time.Minute),
	}
	u, err := storage.SignedURL(bucket, object, opts)
	if err != nil {
		return "", fmt.Errorf("storage.SignedURL: %v", err)
	}
	fmt.Fprintln(w, "Generated PUT signed URL:")
	fmt.Fprintf(w, "%q\n", u)
	fmt.Fprintln(w, "You can use this URL with any user agent, for example:")
	fmt.Fprintf(w, "curl -X PUT -H 'Content-Type: application/octet-stream' --upload-file my-file %q\n", u)
	return u, nil
}

Java

google-cloud-examples/src/main/java/com/google/cloud/examples/storage/objects/GenerateV4PutObjectSignedUrl.java 
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.BlobInfo;
import com.google.cloud.storage.HttpMethod;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageException;
import com.google.cloud.storage.StorageOptions;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

public class GenerateV4PutObjectSignedUrl {
  /**
   * Signing a URL requires Credentials which implement ServiceAccountSigner. These can be set
   * explicitly using the Storage.SignUrlOption.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 URL. See the documentation for Storage.signUrl for more
   * details.
   */
  public static void generateV4GPutObjectSignedUrl(
      String projectId, String bucketName, String objectName) throws StorageException {
    // String projectId = "my-project-id";
    // String bucketName = "my-bucket";
    // String objectName = "my-object";

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

    // Define Resource
    BlobInfo blobInfo = BlobInfo.newBuilder(BlobId.of(bucketName, objectName)).build();

    // Generate Signed URL
    Map<String, String> extensionHeaders = new HashMap<>();
    extensionHeaders.put("Content-Type", "application/octet-stream");

    URL url =
        storage.signUrl(
            blobInfo,
            15,
            TimeUnit.MINUTES,
            Storage.SignUrlOption.httpMethod(HttpMethod.PUT),
            Storage.SignUrlOption.withExtHeaders(extensionHeaders),
            Storage.SignUrlOption.withV4Signature());

    System.out.println("Generated PUT signed URL:");
    System.out.println(url);
    System.out.println("You can use this URL with any user agent, for example:");
    System.out.println(
        "curl -X PUT -H 'Content-Type: application/octet-stream' --upload-file my-file '"
            + url
            + "'");
  }
}

C#

storage/api/Storage.Samples/GenerateV4UploadSignedUrl.cs 

using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;
using System.Net.Http;

public class GenerateV4UploadSignedUrlSample
{
    public string GenerateV4UploadSignedUrl(
        string bucketName = "your-unique-bucket-name",
        string objectName = "your-object-name",
        string credentialFilePath = "my-local-path/my-credential-file-name")
    {
        UrlSigner urlSigner = UrlSigner.FromServiceAccountPath(credentialFilePath);

        var contentHeaders = new Dictionary<string, IEnumerable<string>>
        {
            { "Content-Type", new[] { "text/plain" } }
        };

        // V4 is the default signing version.
        UrlSigner.Options options = UrlSigner.Options.FromDuration(TimeSpan.FromHours(1));

        UrlSigner.RequestTemplate template = UrlSigner.RequestTemplate
            .FromBucket(bucketName)
            .WithObjectName(objectName)
            .WithHttpMethod(HttpMethod.Put)
            .WithContentHeaders(contentHeaders);

        string url = urlSigner.Sign(template, options);
        Console.WriteLine("Generated PUT signed URL:");
        Console.WriteLine(url);
        Console.WriteLine("You can use this URL with any user agent, for example:");
        Console.WriteLine($"curl -X PUT -H 'Content-Type: text/plain' --upload-file my-file '{url}'");
        return url;
    }
}

Cuando el cliente sube un archivo a la URL firmada, puedes activar una segunda función desde esta mutación si quieres tomar medidas adicionales para la carga. Consulta el instructivo de Cloud Storage para obtener más información sobre cómo activar una función de Cloud Functions después de los cambios a un bucket de Cloud Storage.

Pasos siguientes