Cloud Function task handler

Using Cloud Tasks to trigger Cloud Functions.

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

Code sample


To learn how to install and use the client library for Cloud Tasks, see Cloud Tasks client libraries.

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

const sendgrid = require('@sendgrid/mail');

 * Responds to an HTTP request from Cloud Tasks and sends an email using data
 * from the request body.
 * @param {object} req Cloud Function request context.
 * @param {object} req.body The request payload.
 * @param {string} req.body.to_email Email address of the recipient.
 * @param {string} req.body.to_name Name of the recipient.
 * @param {string} req.body.from_name Name of the sender.
 * @param {object} res Cloud Function response context.
exports.sendEmail = async (req, res) => {
  // Get the SendGrid API key from the environment variable.
  const key = process.env.SENDGRID_API_KEY;
  if (!key) {
    const error = new Error(
      'SENDGRID_API_KEY was not provided as environment variable.'
    error.code = 401;
    throw error;

  // Get the body from the Cloud Task request.
  const {to_email, to_name, from_name} = req.body;
  if (!to_email) {
    const error = new Error('Email address not provided.');
    error.code = 400;
    throw error;
  } else if (!to_name) {
    const error = new Error('Recipient name not provided.');
    error.code = 400;
    throw error;
  } else if (!from_name) {
    const error = new Error('Sender name not provided.');
    error.code = 400;
    throw error;

  // Construct the email request.
  const msg = {
    to: to_email,
    from: '',
    subject: 'A Postcard Just for You!',
    html: postcardHTML(to_name, from_name),

  try {
    await sendgrid.send(msg);
    // Send OK to Cloud Task queue to delete task.
    res.status(200).send('Postcard Sent!');
  } catch (error) {
    // Any status code other than 2xx or 503 will trigger the task to retry.

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