Notification API

What is it?

Backend service that exposes a REST API which allows callers to send push notifications asynchronously. Asynchronously means that service is using queuing service (RabbitMQ) to eventually send the notifications.

How to run?

Separate components

1. RabbitMQ:

   docker run -d                   \
       -p 5672:5672 -p 15672:15672 \
       --hostname rmq --name rmq   \
       -v "./rmq-data:/var/lib/rabbitmq" \
       rabbitmq:3.12-management
   

2. PostgreSQL:

   docker build ./psql -t psql:local
   

   Run the image:

   docker run -d                               \
       -p 5432:5432                            \
       --name psql                             \
       -e "POSTGRES_USER=notif_user"           \
       -e "POSTGRES_PASSWORD=notif_pass"       \
       -e "POSTGRES_DB=notification-db"        \
       -v "./psql-data:/bitnami/postgresql"    \
       psql:local
   

3. Spring Boot Application

   ./mvnw spring-boot:run
   

Altogether (docker-compose)

Create an external network in docker to expose Spring Boot Application and RabbitMQ management interface.

docker network create frontend

Build docker images and start the docker services.

docker-compose up --build

Access RabbitMQ Management UI

http://localhost:15672/

What are the endpoints?

Swagger UI

http://localhost:8080/swagger-ui/index.html

Known issues

• Tries to send push notifications to expired (stale) device tokens.

Future plan

• Fix some known issues
• Expose Websockets/gRPC endpoints

Peculiarities

• Note this line in Dockerfile:

  RUN \
      --mount=type=cache,target=/root/.m2 \
      ./mvnw dependency:resolve-plugins dependency:resolve
  

  It utilizes Docker's RUN cache to cache container's .m2 directory. Basically, it avoids a minuscule change in pom.xml to trigger regeneration of entire .m2 directory. Read more about it on Medium or Dev.to.