Create App Engine tasks

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This page demonstrates how to programmatically create App Engine tasks and place them in Cloud Tasks queues. Using this process you can explicitly specify the service and handler that should process the task, and optionally pass task-specific data along to the handler. The Cloud Tasks service forwards the task request to the handler, but this worker is located within App Engine. So all queues that target App Engine handlers must have an App Engine app. The handlers must run in the region where the App Engine app runs. This region also serves as the LOCATION_ID parameter for your Cloud Tasks requests. For more information, see Cloud Tasks queues with App Engine targets.

You can also fine-tune the configuration for the task, like scheduling a time in the future when it should be executed or limiting the number of times you want the task to be retried if it fails. If you chose to specify a name for the task, Cloud Tasks can use that name to ensure task deduplication, although the necessary processing can add increased latency.

App Engine firewall rules

In the App Engine standard environment, the App Engine firewall can allow certain internal traffic to bypass the firewall. This means that if you set the default rule to deny, requests from certain services destined for the App Engine standard environment do not get blocked. These are all types of traffic requested in the app's own configuration, or sent from the same app. Requests that bypass firewall rules in this way also include App Engine tasks in Cloud Tasks (including App Engine Task Queues).

To allow incoming requests, the following are the IP ranges for App Engine tasks in Cloud Tasks (including App Engine Task Queues):

  • IP range for requests sent to the App Engine standard environment: 0.1.0.2/32 (bypasses the default firewall rule if set to deny)

  • IP range for requests sent to the App Engine flexible environment: 0.1.0.2/32

Create tasks using the client libraries

You create tasks in the form of an HTTP request, which you can construct as you like. Using the client libraries however, as the following samples do, can help you manage details of low level communication with the server, including authenticating with Google. For adding a task to a queue, see Add a task to a Cloud Tasks queue

C#


using Google.Cloud.Tasks.V2;
using Google.Protobuf;
using Google.Protobuf.WellKnownTypes;
using System;

class CreateAppEngineTask
{
    public string CreateTask(
        string projectId = "YOUR-PROJECT-ID",
        string location = "us-central1",
        string queue = "my-queue",
        string payload = "Hello World!",
        int inSeconds = 0)
    {
        CloudTasksClient client = CloudTasksClient.Create();
        QueueName parent = new QueueName(projectId, location, queue);

        var response = client.CreateTask(new CreateTaskRequest
        {
            Parent = parent.ToString(),
            Task = new Task
            {
                AppEngineHttpRequest = new AppEngineHttpRequest
                {
                    HttpMethod = HttpMethod.Post,
                    RelativeUri = "/log_payload",
                    Body = ByteString.CopyFromUtf8(payload)
                },
                ScheduleTime = Timestamp.FromDateTime(
                    DateTime.UtcNow.AddSeconds(inSeconds))
            }
        });

        Console.WriteLine($"Created Task {response.Name}");
        return response.Name;
    }
}

Python

"""Create a task for a given queue with an arbitrary payload."""

from google.cloud import tasks_v2
from google.protobuf import timestamp_pb2
import datetime
import json

# Create a client.
client = tasks_v2.CloudTasksClient()

# TODO(developer): Uncomment these lines and replace with your values.
# project = 'my-project-id'
# queue = 'my-appengine-queue'
# location = 'us-central1'
# payload = 'hello' or {'param': 'value'} for application/json
# in_seconds = None

# Construct the fully qualified queue name.
parent = client.queue_path(project, location, queue)

# Construct the request body.
task = {
        'app_engine_http_request': {  # Specify the type of request.
            'http_method': tasks_v2.HttpMethod.POST,
            'relative_uri': '/example_task_handler'
        }
}
if payload is not None:
    if isinstance(payload, dict):
        # Convert dict to JSON string
        payload = json.dumps(payload)
        # specify http content-type to application/json
        task["app_engine_http_request"]["headers"] = {"Content-type": "application/json"}
    # The API expects a payload of type bytes.
    converted_payload = payload.encode()

    # Add the payload to the request.
    task['app_engine_http_request']['body'] = converted_payload

if in_seconds is not None:
    # Convert "seconds from now" into an rfc3339 datetime string.
    d = datetime.datetime.now(tz=datetime.timezone.utc) + datetime.timedelta(seconds=in_seconds)

    # Create Timestamp protobuf.
    timestamp = timestamp_pb2.Timestamp()
    timestamp.FromDatetime(d)

    # Add the timestamp to the tasks.
    task['schedule_time'] = timestamp

# Use the client to build and send the task.
response = client.create_task(parent=parent, task=task)

print('Created task {}'.format(response.name))
return response

Note the requirements.txt file:

Flask==2.1.0; python_version > '3.6'
Flask==2.0.3; python_version < '3.7'
gunicorn==20.1.0
google-cloud-tasks==2.7.1

Java

import com.google.cloud.tasks.v2.AppEngineHttpRequest;
import com.google.cloud.tasks.v2.CloudTasksClient;
import com.google.cloud.tasks.v2.HttpMethod;
import com.google.cloud.tasks.v2.QueueName;
import com.google.cloud.tasks.v2.Task;
import com.google.protobuf.ByteString;
import com.google.protobuf.Timestamp;
import java.nio.charset.Charset;
import java.time.Clock;
import java.time.Instant;

public class CreateTask {
  public static void main(String... args) throws Exception {
    // Instantiates a client.
    try (CloudTasksClient client = CloudTasksClient.create()) {
      // Variables provided by system variables.
      String projectId = System.getenv("GOOGLE_CLOUD_PROJECT");
      String queueName = System.getenv("QUEUE_ID");
      String location = System.getenv("LOCATION_ID");
      // Optional variables.
      String payload = "hello";
      int seconds = 0; // Scheduled delay for the task in seconds

      // Construct the fully qualified queue name.
      String queuePath = QueueName.of(projectId, location, queueName).toString();

      // Construct the task body.
      Task.Builder taskBuilder =
          Task.newBuilder()
              .setAppEngineHttpRequest(
                  AppEngineHttpRequest.newBuilder()
                      .setBody(ByteString.copyFrom(payload, Charset.defaultCharset()))
                      .setRelativeUri("/tasks/create")
                      .setHttpMethod(HttpMethod.POST)
                      .build());

      // Add the scheduled time to the request.
      taskBuilder.setScheduleTime(
          Timestamp.newBuilder()
              .setSeconds(Instant.now(Clock.systemUTC()).plusSeconds(seconds).getEpochSecond()));

      // Send create task request.
      Task task = client.createTask(queuePath, taskBuilder.build());
      System.out.println("Task created: " + task.getName());
    }
  }
}

Note the pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright 2019 Google LLC

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <groupId>com.example.appengine</groupId>
  <artifactId>appengine-tasks-j11</artifactId>

  <!--
    The parent pom defines common style checks and testing strategies for our samples.
    Removing or replacing it should not affect the execution of the samples in anyway.
  -->
  <parent>
    <groupId>com.google.cloud.samples</groupId>
    <artifactId>shared-configuration</artifactId>
    <version>1.2.0</version>
    <relativePath></relativePath>
  </parent>

  <properties>
    <maven.compiler.target>11</maven.compiler.target>
    <maven.compiler.source>11</maven.compiler.source>
  </properties>

  <!--  Using libraries-bom to manage versions.
  See https://github.com/GoogleCloudPlatform/cloud-opensource-java/wiki/The-Google-Cloud-Platform-Libraries-BOM -->
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>com.google.cloud</groupId>
        <artifactId>libraries-bom</artifactId>
        <version>26.1.4</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>google-cloud-tasks</artifactId>
    </dependency>
    <!-- Test dependencies -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.13.2</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.google.truth</groupId>
      <artifactId>truth</artifactId>
      <version>1.1.3</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
    <finalName>tasks</finalName>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>3.3.2</version>
        <configuration>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>3.0.0</version>
        <configuration>
          <mainClass>com.example.task.CreateTask</mainClass>
          <cleanupDaemonThreads>false</cleanupDaemonThreads>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

PHP

use Google\Cloud\Tasks\V2\AppEngineHttpRequest;
use Google\Cloud\Tasks\V2\CloudTasksClient;
use Google\Cloud\Tasks\V2\HttpMethod;
use Google\Cloud\Tasks\V2\Task;

/** Uncomment and populate these variables in your code */
// $projectId = 'The Google project ID';
// $locationId = 'The Location ID';
// $queueId = 'The Cloud Tasks App Engine Queue ID';
// $payload = 'The payload your task should carry to the task handler. Optional';

// Instantiate the client and queue name.
$client = new CloudTasksClient();
$queueName = $client->queueName($projectId, $locationId, $queueId);

// Create an App Engine Http Request Object.
$httpRequest = new AppEngineHttpRequest();
// The path of the HTTP request to the App Engine service.
$httpRequest->setRelativeUri('/task_handler');
// POST is the default HTTP method, but any HTTP method can be used.
$httpRequest->setHttpMethod(HttpMethod::POST);
// Setting a body value is only compatible with HTTP POST and PUT requests.
if (isset($payload)) {
    $httpRequest->setBody($payload);
}

// Create a Cloud Task object.
$task = new Task();
$task->setAppEngineHttpRequest($httpRequest);

// Send request and print the task name.
$response = $client->createTask($queueName, $task);
printf('Created task %s' . PHP_EOL, $response->getName());

Note the composer.json file:

{
    "require": {
        "google/cloud-tasks": "^1.4.0"
    }
}

Go


// Command create_task constructs and adds a task to an App Engine Queue.
package main

import (
	"context"
	"fmt"

	cloudtasks "cloud.google.com/go/cloudtasks/apiv2"
	taskspb "cloud.google.com/go/cloudtasks/apiv2/cloudtaskspb"
)

// createTask creates a new task in your App Engine queue.
func createTask(projectID, locationID, queueID, message string) (*taskspb.Task, error) {
	// Create a new Cloud Tasks client instance.
	// See https://godoc.org/cloud.google.com/go/cloudtasks/apiv2
	ctx := context.Background()
	client, err := cloudtasks.NewClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("NewClient: %v", err)
	}
	defer client.Close()

	// Build the Task queue path.
	queuePath := fmt.Sprintf("projects/%s/locations/%s/queues/%s", projectID, locationID, queueID)

	// Build the Task payload.
	// https://godoc.org/google.golang.org/genproto/googleapis/cloud/tasks/v2#CreateTaskRequest
	req := &taskspb.CreateTaskRequest{
		Parent: queuePath,
		Task: &taskspb.Task{
			// https://godoc.org/google.golang.org/genproto/googleapis/cloud/tasks/v2#AppEngineHttpRequest
			MessageType: &taskspb.Task_AppEngineHttpRequest{
				AppEngineHttpRequest: &taskspb.AppEngineHttpRequest{
					HttpMethod:  taskspb.HttpMethod_POST,
					RelativeUri: "/task_handler",
				},
			},
		},
	}

	// Add a payload message if one is present.
	req.Task.GetAppEngineHttpRequest().Body = []byte(message)

	createdTask, err := client.CreateTask(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("cloudtasks.CreateTask: %v", err)
	}

	return createdTask, nil
}

Node.js

// Imports the Google Cloud Tasks library.
const {CloudTasksClient} = require('@google-cloud/tasks');

// Instantiates a client.
const client = new CloudTasksClient();

async function createTask() {
  // TODO(developer): Uncomment these lines and replace with your values.
  // const project = 'my-project-id';
  // const queue = 'my-appengine-queue';
  // const location = 'us-central1';
  // const payload = 'Hello, World!';

  // Construct the fully qualified queue name.
  const parent = client.queuePath(project, location, queue);

  const task = {
    appEngineHttpRequest: {
      headers: {
        'Content-Type': 'text/plain',
      },
      httpMethod: 'POST',
      relativeUri: '/log_payload',
    },
  };

  if (payload) {
    task.appEngineHttpRequest.body = Buffer.from(payload).toString('base64');
  }

  if (inSeconds) {
    // The time when the task is scheduled to be attempted.
    task.scheduleTime = {
      seconds: inSeconds + Date.now() / 1000,
    };
  }

  console.log('Sending task:');
  console.log(task);

  // Send create task request.
  const request = {parent: parent, task: task};
  const [response] = await client.createTask(request);
  const name = response.name;
  console.log(`Created task ${name}`);
}

createTask();

Note the package.json file:

{
  "name": "appengine-cloudtasks",
  "description": "Google App Engine Cloud Tasks example.",
  "license": "Apache-2.0",
  "author": "Google Inc.",
  "private": true,
  "engines": {
    "node": ">=12.0.0"
  },
  "files": [
    "*.js"
  ],
  "scripts": {
    "test": "mocha --timeout 30000",
    "start": "node server.js"
  },
  "dependencies": {
    "@google-cloud/tasks": "^3.0.4",
    "body-parser": "^1.18.3",
    "express": "^4.16.3"
  },
  "devDependencies": {
    "chai": "^4.2.0",
    "mocha": "^8.0.0",
    "uuid": "^9.0.0"
  }
}

Ruby

require "google/cloud/tasks"

# Create an App Engine Task
#
# @param [String] project_id Your Google Cloud Project ID.
# @param [String] location_id Your Google Cloud Project Location ID.
# @param [String] queue_id Your Google Cloud App Engine Queue ID.
# @param [String] payload The request body of your task.
# @param [Integer] seconds The delay, in seconds, to process your task.
def create_task project_id, location_id, queue_id, payload: nil, seconds: nil
  # Instantiates a client.
  client = Google::Cloud::Tasks.cloud_tasks

  # Construct the fully qualified queue name.
  parent = client.queue_path project: project_id, location: location_id, queue: queue_id

  # Construct task.
  task = {
    app_engine_http_request: {
      http_method:  "POST",
      relative_uri: "/log_payload"
    }
  }

  # Add payload to task body.
  if payload
    task[:app_engine_http_request][:body] = payload
  end

  # Add scheduled time to task.
  if seconds
    timestamp = Google::Protobuf::Timestamp.new
    timestamp.seconds = Time.now.to_i + seconds.to_i
    task[:schedule_time] = timestamp
  end

  # Send create task request.
  puts "Sending task #{task}"
  response = client.create_task parent: parent, task: task

  puts "Created task #{response.name}" if response.name
end

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