springboot-aws-localstack-dynamodb-lambda-sns-sqs

In this project, we are going to use LocalStack to simulate locally, some services provided by AWS Cloud such as: DynamoDB, Lambda, SNS and SQS. Also, in order to simplify the use of AWS managed services, we are going to use Spring Cloud AWS.

Note: Also, take a look at the springboot-aws-localstack-opensearch-s3-secretsmanager repository. There, we have implemented two Spring Boot applications for indexing and searching movies. We also used LocalStack to simulate AWS Cloud services locally, such as OpenSearch, S3, and Secrets Manager.

Proof-of-Concepts & Articles

On ivangfr.github.io, I have compiled my Proof-of-Concepts (PoCs) and articles. You can easily search for the technology you are interested in by using the filter. Who knows, perhaps I have already implemented a PoC or written an article about what you are looking for.

Additional Readings

Project Diagram

Applications

news-producer

Spring Boot Java Web application that exposes a REST API to manage news. It uses DynamoDB as database.

It has the following endpoints:
```
   GET /api/news
   GET /api/news/{id}
  POST /api/news {"title": "..."}
  POST /api/news/randomly
DELETE /api/news/{id}
```
dynamodb-lambda-function

Spring Cloud Function application that uses AWS Adapter to convert it to a form that can run in AWS Lambda.

dynamodb-lambda-function listens to events emitted by an event-source created to monitor changes in DynamoDB news table. Once it receives an event, it processes it and publishes a news event to an SNS topic. Later, SNS publishes the news event to a SQS queue.
news-consumer

Spring Boot Java Web application that polls the news events that are queued in a SQS queue.

Prerequisites

Package dynamodb-lambda-function jar

In a terminal, make sure you inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder
Run the following script
```
./package-dynamodb-lambda-function-jar.sh
```
When Maven packaging finishes, the jar file generated in dynamodb-lambda-function/target folder is copied to dynamodb-lambda-function/shared folder

Start and Initialize LocalStack

In a terminal, make sure you are in inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder
Start LocalStack Docker container
```
DEBUG=1 docker compose up -d
```
[Optional] Debug logs are enabled so that we have more insights about what is happening. To monitor localstack Docker container logs, run the command below
```
docker logs localstack -f
```
Initialize LocalStack by running the following script
```
./init-localstack.sh
```
The script will create:
- create news-topic in SNS;
- create news-consumer-queue in SQS;
- subscribe news-consumer-queue to news-topic;
- create news table in DynamoDB;
- create ProcessDynamoDBEvent Lambda function;
- create an event-source-mapping to connect DynamoDB to ProcessDynamoDBEvent Lambda function.

Running applications with Maven

news-producer

In a terminal and, inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder, run the following command

export AWS_REGION=eu-west-1 && export AWS_ACCESS_KEY_ID=key && export AWS_SECRET_ACCESS_KEY=secret && \
  ./mvnw clean spring-boot:run --projects news-producer

news-consumer

In another terminal and, inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder, run the command below

export AWS_REGION=eu-west-1 && export AWS_ACCESS_KEY_ID=key && export AWS_SECRET_ACCESS_KEY=secret && \
  ./mvnw clean spring-boot:run --projects news-consumer

Running applications as Docker container

Build Docker images

In a terminal and, inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder, run the following script
```
./docker-build.sh
```

Run Docker containers

news-producer

In a terminal, run the following command

docker run --rm --name news-producer -p 9080:9080 \
  -e AWS_REGION=eu-west-1 -e AWS_ACCESS_KEY_ID=key -e AWS_SECRET_ACCESS_KEY=secret \
  --network=springboot-aws-localstack-dynamodb-lambda-sns-sqs_default \
  ivanfranchin/news-producer:1.0.0

news-consumer

In a new terminal, run the command below

docker run --rm --name news-consumer -p 9081:9081 \
  -e AWS_REGION=eu-west-1 -e AWS_ACCESS_KEY_ID=key -e AWS_SECRET_ACCESS_KEY=secret \
  -e NEWS_PRODUCER_URL=http://news-producer:9080 \
  --network=springboot-aws-localstack-dynamodb-lambda-sns-sqs_default \
  ivanfranchin/news-consumer:1.0.0

Application URL

Application	Type	URL
`news-producer`	Swagger	http://localhost:9080/swagger-ui.html
`news-consumer`	UI	http://localhost:9081

Playing around

Creating news

In a terminal, run the following command

curl -i -X POST http://localhost:9080/api/news \
  -H 'Content-Type: application/json' \
  -d '{"title": "Palmeiras is three-time champion of the Copa Libertadores da América"}'

or to create news randomly

curl -i -X POST http://localhost:9080/api/news/randomly

In news-consumer UI, the news should be displayed

Deleting news
- In a terminal, run the following command
```
curl -i -X DELETE http://localhost:9080/api/news/<NEWS-ID>
```
- In news-consumer UI, the news should be removed

Demo

In the GIF below, we use news-producer Swagger UI to create one random news. Then, we delete the news created previously. Finally, we create more two news randomly.

Shutdown

To stop applications, go to the terminal where they are running and press Ctrl+C
To stop and remove docker compose containers, network and volumes, go to a terminal and, inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder, run the following command
```
docker compose down -v
```

Cleanup

To remove the Docker images created by this project, go to a terminal and, inside springboot-aws-localstack-dynamodb-lambda-sns-sqs root folder, run the script below

./remove-docker-images.sh

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