AWS ECS Service Discovery

Project Overview

This project is used as a submodule in the SpringBoot applications. Also, this is non executable project contains AWS ECS ServiceDiscovery SDK implementation.

Scenario: Consider a service “service-a” which has an API which requires some data from “service-b”.

Solution: “service-a” will internally call the api of “service-b” using service discovery mechanism.

Implementation:

• Discover NameSpace
• Get all ECS Instances
• Get all docker containers for specific service
• Randomly pick any service

Most of the Implementation is written in CloudMapServiceLocationResolver.

@Override
public String resolve(String serviceName) {
    final AWSServiceDiscovery awsServiceDiscovery = AWSServiceDiscoveryClientBuilder.defaultClient();
    logger.info("awsServiceDiscovery " + awsServiceDiscovery);
    final DiscoverInstancesRequest discoverInstancesRequest = new DiscoverInstancesRequest();
    discoverInstancesRequest.setNamespaceName(AwsServiceDiscoveryConstants.AWS_CLOUD_NAMESPACE);
    discoverInstancesRequest.setServiceName(serviceName);
    discoverInstancesRequest.setHealthStatus(HealthStatus.HEALTHY.name());
    logger.info("discoverInstancesRequest " + discoverInstancesRequest);

    final DiscoverInstancesResult discoverInstancesResult = awsServiceDiscovery.discoverInstances(discoverInstancesRequest);
    logger.info("discoverInstancesResult" + discoverInstancesResult);
    final List<HttpInstanceSummary> allInstances = discoverInstancesResult.getInstances();
    final List<String> serviceEndpoints = allInstances.stream()
            .map(result -> result.getAttributes().get(AwsServiceDiscoveryConstants.AWS_INSTANCE_IPV_4_ATTRIBUTE) + ":"
                    + result.getAttributes().get(AwsServiceDiscoveryConstants.AWS_INSTANCE_PORT_ATTRIBUTE))
            .collect(Collectors.toList());
    logger.info("Found instances: {}", serviceEndpoints);

    final HttpInstanceSummary result = allInstances.get(RAND.nextInt(allInstances.size()));
    logger.info("result " + result);
    return result.getAttributes()
            .get(AwsServiceDiscoveryConstants.AWS_INSTANCE_IPV_4_ATTRIBUTE) + ":"
            + result.getAttributes().get(AwsServiceDiscoveryConstants.AWS_INSTANCE_PORT_ATTRIBUTE);
}

How to Use this Project

• Use this SpringBoot application as an Internal Project. Either directly copy all the classes in your existing application or Use this SpringBoot project as submodule in your existing application.
• Update the AWS_CLOUD_NAMESPACE in AwsServiceDiscoveryConstants Class

Note:: Make sure to print the logs so that it will help you to understand the communication between infrastructure.