NestJS Messaging Service

This project is a NestJS API that can publish and subscribe to messages on a queue. The queue implementation can be swapped based on environment variables, supporting AWS SQS and RabbitMQ.

Features

• Publish and subscribe to messages on a queue.
• Support for AWS SQS and RabbitMQ.
• Ability to switch between queue providers using environment variables.
• Docker setup for local development and testing.

Prerequisites

• Node.js (v18.x recommended)
• Docker and Docker Compose

Getting Started

Clone the Repository

git clone https://github.com/your-username/nestjs-messaging-service.git
cd nestjs-messaging-service

Installation

$ npm install

Configuration

Create a .env (you can use the .env.example) file in the root directory with the following content:

QUEUE_PROVIDER=all # sqs | rabbitmq | all
SQS_ENDPOINT=http://localstack:4566
SQS_REGION=us-east-1
SQS_QUEUE_URL=http://localstack:4566/000000000000/nestjs-queue
RABBITMQ_URL=amqp://rabbitmq:5672
RABBITMQ_QUEUE=nestjs-queue
AWS_ACCESS_KEY_ID=test
AWS_SECRET_ACCESS_KEY=test

Docker Setup

docker-compose up --build

This will start the NestJS app, LocalStack (for SQS), and RabbitMQ.

Running the application

By default, the application will use the queue provider specified in the .env file. You can change the QUEUE_PROVIDER variable to sqs, rabbitmq, or all to use SQS, RabbitMQ, or both respectively.

Example Usage

To publish a message:

curl -X POST http://localhost:3000/publish -H "Content-Type: application/json" -d '{"message": "Hello, Queue!"}'

To subscribe to messages:

curl http://localhost:3000/subscribe

The message will be displayed on the Docker console.

e.g

app-1         | [Nest] 1  - {Timestamp}     LOG [RabbitMQService] Connected to RabbitMQ
app-1         | [Nest] 1  - {Timestamp}     LOG [AppController] Published message: {Message}

Running Tests

npm test

Stopping the Application

To stop the Docker containers, run:

docker-compose down

Troubleshooting

• If the Docker containers are not running, ensure that the ports 3000 and 6379 are not in use.
• To restart the Docker containers, run:

docker-compose down
docker-compose up --build

500 Error When Posting a New Message

If you encounter a 500 error when posting a new message, try the following steps:

Check the Application Logs: Inspect the logs of the NestJS application to get more details about the error. You can view the logs by running:

• docker-compose logs app

Look for any error messages or stack traces that can give you more information about the cause of the error.

Verify Environment Variables: Ensure that all required environment variables are correctly set in the .env file. Missing or incorrect values can cause the application to fail.

Connectivity Issues: Make sure the application can connect to the queue service. For SQS, check LocalStack status:

• curl http://localhost:4566/_localstack/health

For RabbitMQ, access the management UI at:

• http://localhost:15672

Rebuild Containers: If you made changes to the configuration or environment variables, rebuild the Docker containers:

docker-compose down
docker-compose up --build

If there was an issue running the init-localstack.sh run it manually after the containers are build with

aws --endpoint-url=http://localhost:4566 --region us-east-1 sqs create-queue --queue-name nestjs-queue