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Email service

Email microservice that sends emails based on templates. Can be used as a standalone web service or as an express router.

Running as a command line application

The npm package configures an pnp-email-service executable. You will pass configuration options through ENV variables. Check the configuration options below.

Running as a standalone HTTP server via API

This is the recommended method for running the microservice via API. You can ignore the MICROSERVICE_PORT configuration and this will spin up a server at a random port. Then you can obtain the port the server is running by calling server.address().port. This way the microservice is not exposed in the same port than your main application and you are sure it will run in an available port.

const emailService = require('pnp-email-service')
const config = {
  /* Check the configuration options below */
}
const server = emailService.startServer(config, () => {
  const port = server.address().port
  console.log(`Listening on port ${port}! Send an HTTP POST to http://127.0.0.1:${port}/email/send for sending an email`)
})

Running as an express router

const emailService = require('pnp-email-service')
const config = {
  /* Check the configuration options below */
}
const router = emailService.createRouter(config)
app.use('/email', router)

Invoking

Invoking the service is as simple as doing an HTTP POST request to {baseURL}/send. The baseURL depends on how you are deploying the service. For example if you are running it as an express router mounted in /email in a server running at 127.0.0.1:3000 the URL will be: http(s)://127.0.0.1:3000/email/send.

You need to send a JSON body with the following structure:

{
  "language": "en",
  "templateName": "welcome",
  "templateOptions": {
    "user": {
      "name": "John"
    }
  },
  "emailOptions": {
    "from": "Judy <judy@example.com>",
    "to": "John <john@example.com>"
  }
}

If your {lang}/{templateName}-body-html.ejs template has this content:

<style>
  h1 { color: #777 }
</style>
<h1>Welcome <%= user.name %></h1>
<p>Cheers,</p>

This HTML content will be sent:

<h1 style="color: #777;">Welcome John</h1>
<p>Cheers,</p>

Full example

The following code uses node-fetch as HTTP client library. It spins an HTTP server and provides a simple sendEmail() function:

const fetch = require('node-fetch')
const emailService = require('pnp-email-service')
const emailServer = emailService.startServer(config)

const sendEmail = (templateName, emailOptions, templateOptions, language) => {
  const port = emailServer.address().port
  const url = `http://127.0.0.1:${port}/email/send`
  const body = { templateName, emailOptions, templateOptions, language }
  return fetch(url, {
    method: 'POST',
    body: JSON.stringify(body),
    headers: { 'Content-Type': 'application/json' }
  })
}

// Example usage passing a `user` object to the template
sendEmail('welcome', { to: email }, { user })
  .then(response => console.log('Email sent'))
  .catch(err => console.error(err.stack))

Configuration options

All configuration options can be configured using ENV variables. If using it as an express router, then configuration variables can also be passed as an argument to this method. All ENV variables can be prefixed with EMAIL_. Since one value can be configured in many ways some take precedence over others. For example for the DEFAULT_FROM variable the value used will be the first found following this list:

  • EMAIL_DEFAULT_FROM parameter passed to createRouter() or startServer()
  • DEFAULT_FROM parameter passed to createRouter() or startServer()
  • EMAIL_DEFAULT_FROM ENV variable
  • DEFAULT_FROM ENV variable

This is the list of available configuration options:

Variable Description
MICROSERVICE_PORT Port number for the standalone application. If not specified it will run in a random port
DEFAULT_FROM Default email sender if a from parameter is not specified
DEFAULT_LANGUAGE Default language to be used if a language is not specified. Defaults to en
TRANSPORT Third-party service to be used to send the email. Supported values: [ses, sendgrid, postmark, mailgun, 'smtp'] for production; stub for testing
AWS_KEY AWS Key for sending emails using Amazon SES
AWS_SECRET AWS Secret for sending emails using Amazon SES
AWS_REGION AWS Region for sending emails using Amazon SES
SENDGRID_API_KEY API Key for sending emails when using Sendgrid
POSTMARK_API_KEY API Key for sending emails when using Postmark
MAILGUN_API_KEY API Key for sending emails when using Mailgun
MAILGUN_DOMAIN Domain name from which emails are sent when using Mailgun
SMTP_HOST SMTP host from which emails are sent when using SMTP
SMTP_PORT SMTP port from which emails are sent when using SMTP
SMTP_SECURE SMTP TLS from which emails are sent when using SMTP ("true"/"false")
SMTP_USER SMTP user from which emails are sent when using SMTP
SMTP_PASS SMTP password from which emails are sent when using SMTP
TEMPLATES_DIR Absolute path to directory where templates will be found

Templates

The service will use the following templates:

  • {lang}/{templateName}-body-text.ejs if available it will be used as plain text version of the message
  • {lang}/{templateName}-subject.ejs for the email subject

For the HTML body one of these will be used:

  • {lang}/{templateName}-body-html.ejs HTML template using EJS
  • {lang}/{templateName}-body-html.pug HTML template using PUG

The HTML output of the template is passed through juice for inlining the CSS styles.

Example templates

There are a few example templates available in the example_templates directory of the repo.

Testing your templates

You can test your templates from the command line using tools such as ejs-cli. For example:

ejs-cli example_templates/en/password_reset-body-html.ejs -O '{"name":"John","action_url":"http://","operating_system":"","browser_name":"","supp
ort_url":""}' > password_reset.html

Or you can specify TRANSPORT=stub. This way no real emails will be sent and you will get the rendered templates as response when invoking the service.