Email-Notification-Service

The email notification service is responsible for saving/deleting email addresses per Trubudget user in a connected database. These email addresses are used to send configurable notifications to a connected SMTP server. If database and SMTP server are connected the notification.send endpoint can be used to send a user id. The database is checked if a email address is linked to the passed user id. If so a notification is sent.

Database Configuration

This project is using knex to connect to the database where user email addresses are stored. Knex makes it possible to choose from a pool of supported databases. Supported databases are:

Database	Driver
PostgreSQL/Amazon Redshift	pg
MySQL/MariaDB	mysql
SQLite3	sqlite3
MSSQL	mssql

To install the driver for your database type in following command:

npm install <Driver> --save

Architecture

As shown in the architecture section below, a script shall filter every transaction. This script is called multichain-feed and is part of the mono repository of Trubudget. The script filters transactions after notifications and saves them locally named with a timestamp as json files in the /notifications folder of the blockchain application. An external process called notification-watcher watches the notifications folder and sends the user's ids parsed from the saved transactions via http request to the email service using the notification.send endpoint. The email service checks if the connected database includes an email address for the passed user id. If an email address is found a notification is sent to the configured SMTP host. Subscribing/unsubscribing to the email notification service can be handled by the user profile of the Trubudget frontend or by using the user.insert/user.delete endpoint of the email service.

Email-Service

Getting Started

The easiest way to get started is to use our docker compose setup which starts the whole TruBudget application including all email components (that means you need to install Docker).

cd docker-compose
cp .env.example .env
docker compose --project-directory . -f blockchain/docker-compose.alphanode.yml -f api/docker-compose.yml -f frontend/docker-compose.yml -f email-notification-service/docker-compose.yml up

The pre-set cluster contains:

• 1 Alpha-Node
• 1 Alpha API connected to Alpha-Node
• 1 Frontend connected to Alpha-API
• 1 Email-Service
• 1 Email-Database (Postgres)

When started, the Email-Service sends email notifications to the configured SMTP-host. The default configuration is:

• SMTP_HOST: host.docker.internal(localhost)
• SMTP_PORT: 2500

To configure another database type for storing the user email addresses check out the database configuration section If a local SMTP mail server for testing purposes is needed mailslurper can be used

Environment Variables

To check the possible configurations in the email-notification service check out the list of Environment Variables

Enable email notifications

If EMAIL_SERVICE_ENABLED is set to "true" and EMAIL_HOST and EMAIL_PORT are set too the multichain-feed is attached to the multichaindaemon and the notification-watcher starts watching the NOTIFICATION_PATH for new incoming notification transactions. In other words The blockchain starts the background processes to send user ids to the email-notification service. EMAIL_SSL is a flag to define if the connection of the blockchain application and the email-service shall be https(true) or http(false).

Disable email notifications

To disable email notifications for blockchain simply set the EMAIL_SERVICE_ENABLED to "false" or unset it. If disabled the multichain-feed is not applied to the multichain-deamon and notifications are not created.

Hint: To prevent the frontend requesting an email-notifcations readiness call simply unset the email notification service environment variable in the frontend. More details can be found in the frontend documentation

Endpoints

Method	Endpoint	Description
GET	/readiness	Checks if email service and its database is ready
GET	/liveness	Checks if email service is up
GET	/version	Get the current version of the service
GET	/user.getEmail	Get email address of id if set in connected database
POST	/user.insert	Insert an email address linked to the passed id
POST	/user.update	Update an email address linked to the passed id
POST	/user.delete	Delete an email address linked to the passed id
POST	/notification.send	Send a notification to passed id if email address is available

/readiness

Neither parameter nor JWT-TOKEN required

/version

Neither parameter nor JWT-TOKEN required

/user.getEmail

Query-Parameter	Description
id	User id

JWT-TOKEN required

/user.insert

Following json structure is used:

{
  "apiVersion": "1.0",
  "data": {
    "user": {
      "id": "mstein",
      "email": "mstein@kfw.de"
    }
  }
}

JWT-TOKEN required

/user.update

Following json structure is used:

{
  "apiVersion": "1.0",
  "data": {
    "user": {
      "id": "mstein",
      "email": "mstein@kfw.de"
    }
  }
}

JWT-TOKEN required

/user.delete

Following json structure is used:

{
  "apiVersion": "1.0",
  "data": {
    "user": {
      "id": "mstein",
      "email": "mstein@kfw.de"
    }
  }
}

JWT-TOKEN required

/notification.send

Following json structure is used:

{
  "id": "mstein"
}

JWT-TOKEN required