Push Notifications Implementation

[bryce-mcmath]

Push Notifications in BC Wallet

Intro

We've been implementing Firebase push notifications in BC Wallet, and I thought I should put this guide and list of notables together for other Bifold teams looking to implement their own Firebase push notifications and for other BC Wallet devs to get up to speed quickly without missing any key details.

Overview

There are several components to get push notifications working end-to-end: setting up a Firebase project for your iOS and Android apps, adding relevant keys, a dependency and module addition in Bifold, Firebase installation and setup in bc-wallet-mobile, mediator logic and Firebase implementation in bc-wallet-mobile, and an addition to the aries-mediator-service to include an FCM plugin. You'll also have to add relevant environment variables to bc-wallet-mobile and aries-mediator-service.

Setting Up Firebase Project

To setup a Firebase project for your application as we did for BC Wallet, follow along with the below video:
Firebase Project Initial Setup

You will need to add a iOS plist file and equivalent Android JSON file to your app project, as seen in the above video. These contain an API key but it's ok to check into source control as explained by the Firebase team here.

In addition to the above steps you will need to add an APNs Auth Key to your iOS project config in the Firebase console, otherwise, iOS notifications won't be delivered.

Then you will need to generate a service account key to be used in the mediator. This key contains sensitive information and should not be checked in to SCM. Follow along with the below video:
Firebase Key for Mediator

Setting up aries-mediator-service (optional)

After completing the above steps, you can now setup a local instance of aries-mediator-service. Clone the repo here and add the following to your .env:

USE_FIREBASE_PLUGIN=true
FIREBASE_PROJECT_ID=<firebase project id>
FIREBASE_NOTIFICATION_TITLE=You have important information in your digital wallet
FIREBASE_NOTIFICATION_BODY=Please open your wallet
FIREBASE_SERVICE_ACCOUNT=<flattened json service account key from the above step: looks like: {"type":"service_account", ... "universe_domain":"googleapis.com"}>
NGROK_AUTHTOKEN=<your ngrok authtoken here>

A free tier ngrok account will work but only for an hour before it will need to be restarted.

After adding the above .env vars, run the following commands to build and run the dockerized local mediator:

docker-compose build
docker-compose up

This will generate an invitation url in the console above the QR code. You will need to supply this URL to the BC Wallet in it's .env file.

Setup BC Wallet

Add the following to your bc-wallet-mobile .env:

LOAD_STORYBOOK=false
OCA_URL=https://raw.githubusercontent.com/bcgov/aries-oca-bundles/main/
MEDIATOR_URL=<if using a local mediator, use the invitation url generated from the above steps>
MEDIATOR_USE_PUSH_NOTIFICATIONS=true

Then build bc-wallet-mobile as usual with Android Studio or Xcode. After completing onboarding or entering your PIN, you will see a popup modal for push notifications. Select continue and then allow notifications on the resulting native popup that appears. For now, since push notifications are a developer setting, enable developer mode and toggle on push notifications.

You will now receive push notifications when your app is closed or backgrounded. You can easily test this with a Traction tenant by creating a connection to your BC Wallet, closing the app, and then sending your BC Wallet connection a message from Traction.

Notes and things to be aware of

1. In the aries-mediator-service code, there is a constant called MAX_SEND_RATE_MINUTES. This is currently set to 2 and is the time needed between mediator messages in order to send a notification. This is to prevent repetitive notifications for sequential messages sent close together. We can discuss if we want to keep this behaviour but I think it's beneficial.
2. Aries Askar / Indy VDR needs to be fixed before we can use the latest version of the react-native-firebase libs: See here
3. Eventually when the in-app guides are GA we will need to add some conditional logic to prevent both modals from being mounted at the same time (the in app guide modal and the push notification modal). Otherwise when the app loads for the first time both modals will attempt to be mounted at the same time and will cause issues on iOS
4. I had to add a little bit of native code to AppDelegate.m for iOS and MainActivity.java for Android to remove all notification badges on app open. Otherwise the notifications won't be properly dismissed.