This sample project deploys a Java 21 Spring Boot application on Amazon ECS using AWS Fargate with Application Load Balancer to route traffic between two ECS Tasks.

Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/alb-ecs-java-sam

Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the AWS Pricing page for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.

• Create an AWS account if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
• AWS CLI installed and configured
• Git Installed
• AWS Serverless Application Model (AWS SAM) installed
• Java 21 or above installed
• Maven 3.8.6 or above installed
• Docker installed
• jq installed

1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:

      git clone https://github.com/aws-samples/serverless-patterns

2. Change directory to the pattern directory:

      cd serverless-patterns/alb-ecs-java-sam

3. From the command line, execute the below command to build the project.

      mvn clean package

4. (Optional) Run the application on local box using the below command:

      mvn spring-boot:run

   Once the application starts, use the below command to insert data into the in-memory database. The script uses POST API exposed by the Spring Boot application:

      bash create-books-local.sh

   Retrieve the data using using the below script. The script calls the GET API exposed by the Spring Boot application:

      bash retrieve-all-books-local.sh

   Delete a booking data using the below script. The script calls the DELETE API exposed by the Spring Boot application. Please enter one of the bookId from previous GET API call:

      bash delete-book-local.sh

5. Please ensure that docket is up and running before executing this step. From the command line, run the below command to create ECR repository, build the docker image and push it into the ECR repository.

      bash build.sh

6. Run the below command to deploy the AWS resources for the pattern as specified in the template.yml file:

      sam deploy --guided

7. During the prompts:

   • Enter a stack name
   • Enter the same as AWS Region that you provided while building the image.
   • ImageURI Enter the image URI obtained from the previous output.
   • Allow SAM CLI to create IAM roles with the required permissions.
   • Keep default values to the rest of the parameters.

   If you have run sam deploy --guided mode once and saved arguments to a configuration file (samconfig.toml), you can use sam deploy in future to use these defaults.

8. Note the outputs from the SAM deployment process. These contain the resource names and/or ARNs which are used for next step as well as testing.

This sample project deploys a Java 21 Spring Boot application on Amazon ECS Fargate with Application Load Balancer to route traffic between two ECS Tasks. The application exposed REST APIs which can be accessed over HTTP.

Please refer to the architecture diagram below:

Here's a breakdown of the steps:

1. Amazon Elastic Container Registry: The repository of the container image of the Spring Boot Application.

2. Application Load Balancer: Receives the HTTP request which routes the traffic to one of the Amazon ECS Tasks.

3. Amazon Elastic Container Service: Amazon ECS Cluster is configured with one service having 2 Tasks. The 2 Tasks runs the Spring Boot application as container. The container image is retrieved from the Amazon Elastic Container Registry. The application uses in-memory database to store the data.

1. Run the below command to create records (books) by invoking the REST API. Provide the Application Load Balancer DNS when asked. The ALB DNS is available in the output of sam deploy --guided:

   bash create-books-aws.sh

2. Run the below command to retrieve the list of books. Provide the Application Load Balancer DNS when asked. The ALB DNS is available in the output of sam deploy --guided:

   bash retrieve-all-books-aws.sh

3. The Application Load Balancer is distributing traffic between two Amazon ECS Tasks. To validat it, please execute the below commands multiple times. This should return two different IP Addresses alternatively.

   curl http://{ECSALBDNSName}/books/container-ip

1. To delete the resources deployed to your AWS account via AWS SAM, run the following command:

   sam delete

2. To delete the ECR registry execute the below command:

   bash delete-ecr-repo.sh

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