eureka-legacy-registrar

A small lib to allow registration of legacy applications in Eureka service discovery. It also comes with (optional) Spring Boot support with annotations making it very easy to use together with Spring Boot.

Typical use cases

Some typical use cases where the eureka-legacy-registrar lib can be very useful:

You are introducing Eureka in an existing architecture

The eureka-legacy-registrar lib will make it very easy to register all existing services in Eureka so that new, and migrated, applications can use a Eureka-only solution rather than having a mix of using service discovery and the previous legacy solutions of finding services it needs to talk to.

This also allows for the existing services to get Eureka-enabled independently and in a pace suitable for the respective development team.

You are unable to affect legacy applications

If you, for whatever reason, have an existing application that you are unable to have register itself in Eureka, either by changing its codebase or by having a side-car process, then the eureka-legacy-registrar will allow you to register that application in Eureka. This scenario could, for example, be caused by 3rd party applications, or applications where it is impossible to affect either code or deployments.

Examples

Check out the example code in the test package for code examples.

Spring Boot example

Just add the @EnableEurekaLegacyRegistrarannotation and appropriate configuration in your application.yml and you are good to go.

Eg.:

@EnableEurekaLegacyRegistrar
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

An example of an application.yml for registering two different services, where one service have two instances:

eureka:
  legacy:
    client:
      serviceUrlDefault: http://eureka-server-1:8761/eureka/,http://eureka-server-2:8761/eureka/
  
    instances:
      -
        appName: legacy-app
        virtualHostName: legacy-app
        instanceId: 10.0.1.15:legacy-app:1 # instanceId should be unique per instance
        hostName: 10.0.1.15
        ipAddress: 10.0.1.15 # optional property ipAddress
        nonSecurePort: 8083 # optional, will default to 8080
        healthCheckUrl: http://10.0.1.15:8081/manage/health #optional
        statusPageUrl: http://10.0.1.15:8081/manage/info #optional
        instanceEnabledOnit: true #optional, will default to true
      -
        appName: legacy-app
        virtualHostName: legacy-app
        instanceId: 10.0.1.18:legacy-app:2
        hostName: 10.0.1.18
        ipAddress: 10.0.1.18 
        nonSecurePort: 8083
        healthCheckUrl: http://10.0.1.18:8081/manage/health
        statusPageUrl: http://10.0.1.18:8081/manage/info
        instanceEnabledOnit: true
      -
        appName: legacy-app-2
        virtualHostName: legacy-app-2
        instanceId: 10.0.1.18:legacy-app-2:1
        hostName: 10.0.1.18
        ipAddress: 10.0.1.18
        nonSecurePort: 8183
        healthCheckUrl: http://10.0.1.18:8180/
        statusPageUrl: http://10.0.1.18:8180/
        instanceEnabledOnit: true

Non-Spring Boot example

Create an instance of EurekaLegacyRegistrarApplication and place your configuration in a file called eureka-client.properties.

Eg.:

final EurekaLegacyRegistrarApplication application = new EurekaLegacyRegistrarApplication();
application.start();

An example of an eureka-client.properties for registering two different services, where one service have two instances:

eureka.preferSameZone=true
eureka.shouldUseDns=false
eureka.serviceUrl.default=http://localhost:8761/eureka/

eureka.decoderName=JacksonJson


eureka.legacy.app0.name=legacy-app
eureka.legacy.app0.vipAddress=legacy-app
# instanceId should be unique per instance
eureka.legacy.app0.instanceId=10.0.1.15:legacy-app:1
eureka.legacy.app0.hostName=10.0.1.15
# optional property ipAddress
eureka.legacy.app0.ipAddress=10.0.1.15
eureka.legacy.app0.port=8080
eureka.legacy.app0.healthCheckUrl=http://10.0.1.15:8081/manage/health
eureka.legacy.app0.statusPageUrl=http://10.0.1.15:8081/manage/info
eureka.legacy.app0.traffic.enabled=true

eureka.legacy.app1.name=legacy-app
eureka.legacy.app1.vipAddress=legacy-app
eureka.legacy.app1.instanceId=10.0.1.15:legacy-app:2
eureka.legacy.app1.hostName=10.0.1.18
eureka.legacy.app1.ipAddress=10.0.1.18
eureka.legacy.app1.port=8080
eureka.legacy.app1.healthCheckUrl=http://10.0.1.18:8081/manage/health
eureka.legacy.app1.statusPageUrl=http://10.0.1.18:8081/manage/info
eureka.legacy.app1.traffic.enabled=true

eureka.legacy.app2.name=legacy-app-2
eureka.legacy.app2.vipAddress=legacy-app-2
eureka.legacy.app2.instanceId=10.0.1.15:legacy-app-2:1
eureka.legacy.app2.hostName=10.0.1.18
eureka.legacy.app2.ipAddress=10.0.1.18
eureka.legacy.app2.port=8180
eureka.legacy.app2.healthCheckUrl=http://10.0.1.18:8080/manage/health
eureka.legacy.app2.statusPageUrl=http://10.0.1.18:8080/manage/info
eureka.legacy.app2.traffic.enabled=true

Releases

Releases are available at the Maven central repository. Or you can just use the source code/binaries directly from GitHub if you prefer that.

Maven

<dependency>
    <groupId>se.sawano.eureka</groupId>
    <artifactId>legacy-registrar</artifactId>
    <version>0.0.6</version>
</dependency>

Gradle

'se.sawano.eureka:legacy-registrar:0.0.6'