Express Cloud Tasks

Express Cloud Tasks intends to facilitate the integration between Google Cloud Tasks and Express' applications.

Installation

npm

npm install @enviabybus/express-cloud-tasks

yarn

yarn add @enviabybus/express-cloud-tasks

Usage

const express = require('express');
const { CloudTasks } = require('express-cloud-tasks');

const app = express();

const cloudTasks = CloudTasks({
  handlerPath: '/my-cloud-tasks-handler',
  location: 'us-central1', // The region where your App Engine is configured
  project: 'awesome-project-1234',
  serviceUrl: 'https://awesome-project-uc.a.run.app',
});

const myQueue = cloudTasks.addQueue('my-queue');

myQueue.addHandler('the-handler-id', (message) => {
  console.log(message);
});

myQueue.addTask('the-handler-id', ['this day was crazy']);
myQueue.addTask(
  'the-handler-id',
  ['this will be crazy'],
  { // https://cloud.google.com/tasks/docs/reference/rest/v2beta3/projects.locations.queues.tasks#Task.FIELDS
    dispatchDeadline: 30000, // milliseconds
    scheduleTime: new Date(60000 + Date.now()), // delayed in 60 seconds
  }
);

app.use(cloudTasks.api);

Cloud Tasks will call the handler API and log this day was crazy and this day will be crazy after 60 seconds.

Using Authentication token on the handler API

First you need to configure a service account to invoke your service. After that you just have to add the service account name on you Cloud Task config:

const cloudTasks = CloudTasks({
  handlerPath: '/my-cloud-tasks-handler',
  location: 'us-central1', // The region where your App Engine is configured
  project: 'awesome-project-1234',
  serviceUrl: 'https://awesome-project-uc.a.run.app',
  serviceAccount: 'my-service-invoker-service-account',
});

app.use(cloudTasks.api);

Configuring Cloud Task queues

const cloudTasks = CloudTasks({
  handlerPath: '/my-cloud-tasks-handler',
  location: 'us-central1', // The region where your App Engine is configured
  project: 'awesome-project-1234',
  serviceUrl: 'https://awesome-project-uc.a.run.app',
  rateLimits: { // https://cloud.google.com/tasks/docs/reference/rest/v2beta3/projects.locations.queues#RateLimits
    maxDispatchesPerSecond: number,
    maxBurstSize: number,
    maxConcurrentDispatches: number
  },
  retryConfig: { // https://cloud.google.com/tasks/docs/reference/rest/v2beta3/projects.locations.queues#retryconfig
    maxAttempts: number,
    maxRetryDuration: number, // in milliseconds
    minBackoff: number, // in milliseconds
    maxBackoff: number, // in milliseconds
    maxDoublings: number,
  };
});

const myQueue = cloudTasks.addQueue('my-queue'); // Uses CloudTasks queue configuration

const mySecondQueue = cloudTasks.addQueue('my-second-queue', { // overrides CloudTasks queue configuration
  rateLimits: {
    maxDispatchesPerSecond: number,
    maxBurstSize: number,
    maxConcurrentDispatches: number
  },
  retryConfig: {
    maxAttempts: number,
    maxRetryDuration: number, // in milliseconds
    minBackoff: number, // in milliseconds
    maxBackoff: number, // in milliseconds
    maxDoublings: number,
  };
});

Creating a service account to associate with the tasks

1. Create the service account:

gcloud iam service-accounts create SERVICE_ACCOUNT_NAME \
   --display-name "DISPLAYED_SERVICE_ACCOUNT_NAME"

Replace:

• SERVICE_ACCOUNT_NAME with a lower case name unique within your Google Cloud project, for example my-invoker-service-account-name.
• DISPLAYED_SERVICE_ACCOUNT_NAME with the name you want to display for this service account, for example, in the console, for example, My Invoker Service Account.

2. For Cloud Run, give your service account permission to invoke your service:

gcloud run services add-iam-policy-binding SERVICE \
   --member=serviceAccount:SERVICE_ACCOUNT_NAME@PROJECT_ID.iam.gserviceaccount.com \
   --role=roles/run.invoker

Replace:

• SERVICE with the name of the service you want to be invoked by Cloud Tasks.
• SERVICE_ACCOUNT_NAME with the name of the service account.
• PROJECT_ID with your Google Cloud project ID.

More details in Cloud Google web site.