Consul and the Micronaut Framework - Microservices Service Discovery

Use Consul service discovery to expose your Micronaut applications.

Authors: Sergio del Amo

Micronaut Version: 3.2.7

1. Getting Started

In this guide, we will create three microservices and register them with Consul Service discovery.

Consul is a distributed service mesh to connect, secure, and configure services across any runtime platform and public or private cloud

You will discover how the Micronaut framework eases Consul integration.

2. What you will need

To complete this guide, you will need the following:

  • Some time on your hands

  • A decent text editor or IDE

  • JDK 1.8 or greater installed with JAVA_HOME configured appropriately

3. Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

4. Writing the App

Let’s describe the microservices you will build through the guide.

  • bookcatalogue - It returns a list of books. It uses a domain consisting of a book name and ISBN.

  • bookinventory - It exposes an endpoint to check whether a book has sufficient stock to fulfil an order. It uses a domain consisting of a stock level and ISBN.

  • bookrecommendation - It consumes previous services and exposes an endpoint which recommends book names which are in stock.

Initially we will hard-code the addresses where the different services are in the bookcatalogue service.

hardcoded

As shown in the previous image, the bookcatalogue hardcodes references to its collaborators.

In the second part of this guide we will use a discovery service.

About registration patterns

We will use a self‑registration pattern. Thus, each service instance is responsible for registering and deregistering itself with the service registry. Also, if required, a service instance sends heartbeat requests to prevent its registration from expiring.

Services register when they start up:

discovery service registration

We will use client‑side service discovery, clients query the service registry, select an available instance, and make a request.

discovery service flow

4.1. Catalogue Microservice

Create the bookcatalogue microservice using the Micronaut Command Line Interface or with Micronaut Launch.

mn create-app --features=discovery-consul,management,graalvm example.micronaut.bookcatalogue --build=maven --lang=groovy
If you don’t specify the --build argument, Gradle is used as the build tool.
If you don’t specify the --lang argument, Java is used as the language.

If you use Micronaut Launch, select Micronaut Application as application type and add the discovery-consul, management, and graalvm features.

The previous command creates a directory named bookcatalogue and a Micronaut application inside it with default package example.micronaut.

If you have an existing Micronaut application and want to add the functionality described here, you can view the dependency and configuration changes from the specified features and apply those changes to your application.

Create a BooksController class to handle incoming HTTP requests into the bookcatalogue microservice:

bookcatalogue/src/main/groovy/example/micronaut/BooksController.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get

@CompileStatic
@Controller("/books") (1)
class BooksController {

    @Get (2)
    List<Book> index() {
        [
            new Book("1491950358", "Building Microservices"),
            new Book("1680502395", "Release It!"),
            new Book("0321601912", "Continuous Delivery:")
        ]
    }
}
1 The class is defined as a controller with the @Controller annotation mapped to the path /
2 The @Get annotation maps the index method to an HTTP GET request on /books

The previous controller responds a List<Book>. Create the Book POJO:

bookcatalogue/src/main/groovy/example/micronaut/Book.groovy
package example.micronaut

import groovy.transform.CompileStatic
import groovy.transform.EqualsAndHashCode
import io.micronaut.core.annotation.Creator
import io.micronaut.core.annotation.Introspected
import io.micronaut.core.annotation.NonNull

import javax.validation.constraints.NotBlank

@CompileStatic
@EqualsAndHashCode
@Introspected
class Book {

    @NonNull
    @NotBlank
    final String isbn

    @NonNull
    @NotBlank
    final String name

    @Creator
    Book(@NonNull @NotBlank String isbn,
         @NonNull @NotBlank String name) {
        this.isbn = isbn
        this.name = name
    }
}

Write a test:

bookcatalogue/src/test/groovy/example/micronaut/BooksControllerSpec.groovy
package example.micronaut

import io.micronaut.core.type.Argument
import io.micronaut.http.HttpRequest
import io.micronaut.http.client.HttpClient
import io.micronaut.http.client.annotation.Client
import io.micronaut.test.extensions.spock.annotation.MicronautTest
import jakarta.inject.Inject
import spock.lang.Specification

@MicronautTest (1)
class BooksControllerSpec extends Specification {

    @Inject
    @Client("/")
    HttpClient client (2)

    void "it is possible to retrieve books"() {
        when:
        HttpRequest request = HttpRequest.GET("/books") (3)
        List<Book> books = client.toBlocking().retrieve(request, Argument.listOf(Book)) (4)

        then:
        books.size() == 3
        books.contains(new Book("1491950358", "Building Microservices"))
        books.contains(new Book("1680502395", "Release It!"))
    }
}
1 Annotate the class with @MicronautTest so the Micronaut framework will initialize the application context and the embedded server. More info.
2 Inject the HttpClient bean and point it to the embedded server.
3 Creating HTTP Requests is easy thanks to the Micronaut framework fluid API.
4 Parse easily JSON into Java objects.

Edit application.yml

bookcatalogue/src/main/resources/application.yml
micronaut:
  application:
    name: bookcatalogue (1)
1 Configure the application name. The application name will be used by the discovery service.

Modify the Application class to use dev as a default environment:

The Micronaut framework supports the concept of one or many default environments. A default environment is one that is only applied if no other environments are explicitly specified or deduced.

bookcatalogue/src/main/groovy/example/micronaut/Application.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.runtime.Micronaut

import static io.micronaut.context.env.Environment.DEVELOPMENT

@CompileStatic
class Application {

    static void main(String[] args) {
        Micronaut.build(args)
                .mainClass(Application)
                .defaultEnvironments(DEVELOPMENT)
                .start()
    }
}

Create src/main/resources/application-dev.yml. The Micronaut framework applies this configuration file only for the dev environment.

bookcatalogue/src/main/resources/application-dev.yml
micronaut:
  server:
    port: 8081 (1)
1 Configure the application to listen on port 8081

Create a file named application-test.yml which is used in the test environment:

bookcatalogue/src/test/resources/application-test.yml
consul:
  client:
    registration:
      enabled: false

Run the unit test:

bookcatalogue
./mvnw test

4.2. Inventory Microservice

Create the bookinventory microservice using the Micronaut Command Line Interface or with Micronaut Launch.

mn create-app --features=discovery-consul,management,graalvm example.micronaut.bookinventory --build=maven --lang=groovy
If you don’t specify the --build argument, Gradle is used as the build tool.
If you don’t specify the --lang argument, Java is used as the language.

If you use Micronaut Launch, select Micronaut Application as application type and add the discovery-consul, management, and graalvm features.

The previous command creates a directory named bookinventory and a Micronaut application inside it with default package example.micronaut.

If you have an existing Micronaut application and want to add the functionality described here, you can view the dependency and configuration changes from the specified features and apply those changes to your application.

Create a Controller:

bookinventory/src/main/groovy/example/micronaut/BooksController.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import io.micronaut.http.annotation.Produces

import javax.validation.constraints.NotBlank

import static io.micronaut.http.MediaType.TEXT_PLAIN

@CompileStatic
@Controller("/books") (1)
class BooksController {

    @Produces(TEXT_PLAIN) (2)
    @Get("/stock/{isbn}") (3)
    Boolean stock(@NotBlank String isbn) {
        bookInventoryByIsbn(isbn).map(bi -> bi.stock > 0).orElse(null)
    }

    private Optional<BookInventory> bookInventoryByIsbn(String isbn) {
        if (isbn == "1491950358") {
            return Optional.of(new BookInventory(isbn, 4))
        }
        if (isbn == "1680502395") {
            return Optional.of(new BookInventory(isbn, 0))
        }
        Optional.empty()
    }
}
1 The class is defined as a controller with the @Controller annotation mapped to the path /books
2 By default, Content-Type of a controller response is application/json : override this with text/plain since we are returning a String, not a JSON object.
3 The @Get annotation maps the index method to an HTTP GET request on /books/stock/{isbn}

Create the POJO used by the controller:

bookinventory/src/main/groovy/example/micronaut/BookInventory.groovy
package example.micronaut

import groovy.transform.CompileStatic
import groovy.transform.EqualsAndHashCode
import io.micronaut.core.annotation.Introspected
import io.micronaut.core.annotation.NonNull

import javax.validation.constraints.NotBlank

@CompileStatic
@EqualsAndHashCode
@Introspected
class BookInventory {

    @NonNull
    @NotBlank
    final String isbn

    final int stock

    BookInventory(@NonNull @NotBlank String isbn,
                  int stock) {
        this.isbn = isbn
        this.stock = stock
    }
}

Write a test:

bookinventory/src/test/groovy/example/micronaut/BooksControllerSpec.groovy
package example.micronaut

import io.micronaut.http.HttpRequest
import io.micronaut.http.HttpResponse
import io.micronaut.http.client.HttpClient
import io.micronaut.http.client.annotation.Client
import io.micronaut.http.client.exceptions.HttpClientResponseException
import io.micronaut.test.extensions.spock.annotation.MicronautTest
import jakarta.inject.Inject
import spock.lang.Specification

import static io.micronaut.http.HttpStatus.NOT_FOUND
import static io.micronaut.http.HttpStatus.OK

@MicronautTest
class BooksControllerSpec extends Specification {

    @Inject
    @Client("/")
    HttpClient httpClient

    void "for a book with inventory true is returned"() {
        when:
        HttpResponse<Boolean> rsp = httpClient.toBlocking().exchange(
                HttpRequest.GET("/books/stock/1491950358"), Boolean)

        then:
        rsp.status() == OK
        rsp.body()
    }

    void "for an invalid ISBN 404 is returned"() {
        when:
        httpClient.toBlocking().exchange(HttpRequest.GET("/books/stock/XXXXX"), Boolean)

        then:
        HttpClientResponseException e = thrown()
        e.response.status == NOT_FOUND
    }
}

Edit application.yml

bookinventory/src/main/resources/application.yml
micronaut:
  application:
    name: bookinventory (1)
1 Configure the application name. The name will be used later in the guide.

Modify the Application class to use dev as a default environment:

The Micronaut framework supports the concept of one or many default environments. A default environment is one that is only applied if no other environments are explicitly specified or deduced.

bookinventory/src/main/groovy/example/micronaut/Application.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.runtime.Micronaut

import static io.micronaut.context.env.Environment.DEVELOPMENT

@CompileStatic
class Application {

    static void main(String[] args) {
        Micronaut.build(args)
                .mainClass(Application)
                .defaultEnvironments(DEVELOPMENT)
                .start()
    }
}

Create src/main/resources/application-dev.yml. The Micronaut framework applies this configuration file only for the dev environment.

bookinventory/src/main/resources/application-dev.yml
micronaut:
  server:
    port: 8082 (1)
1 Configure the application to listen on port 8082

Create a file named application-test.yml which is used in the test environment:

bookinventory/src/test/resources/application-test.yml
consul:
  client:
    registration:
      enabled: false

Run the unit test:

bookinventory
./mvnw test

4.3. Recommendation Microservice

Create the bookrecommendation microservice using the Micronaut Command Line Interface or with Micronaut Launch.

mn create-app --features=discovery-consul,management,reactor,graalvm example.micronaut.bookrecommendation --build=maven --lang=groovy
If you don’t specify the --build argument, Gradle is used as the build tool.
If you don’t specify the --lang argument, Java is used as the language.

If you use Micronaut Launch, select Micronaut Application as application type and add the discovery-consul, management, reactor, and graalvm features.

The previous command creates a directory named bookrecommendation and a Micronaut application inside it with default package example.micronaut.

If you have an existing Micronaut application and want to add the functionality described here, you can view the dependency and configuration changes from the specified features and apply those changes to your application.

Create an interface to map operations with bookcatalogue, and a Micronaut Declarative HTTP Client to consume it.

bookrecommendation/src/main/groovy/example/micronaut/BookCatalogueOperations.groovy
package example.micronaut

import org.reactivestreams.Publisher

interface BookCatalogueOperations {
    Publisher<Book> findAll()
}
bookrecommendation/src/main/groovy/example/micronaut/BookCatalogueClient.groovy
package example.micronaut

import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client
import io.micronaut.retry.annotation.Recoverable
import org.reactivestreams.Publisher

@Client("http://localhost:8081") (1)
@Recoverable(api = BookCatalogueOperations)

interface BookCatalogueClient extends BookCatalogueOperations {

    @Get("/books")
    Publisher<Book> findAll()
}
1 Use @Client to use declarative HTTP Clients

The client returns a POJO. Create it in the bookrecommendation:

bookrecommendation/src/main/groovy/example/micronaut/Book.groovy
package example.micronaut

import groovy.transform.CompileStatic
import groovy.transform.EqualsAndHashCode
import io.micronaut.core.annotation.Introspected
import io.micronaut.core.annotation.NonNull

import javax.validation.constraints.NotBlank

@CompileStatic
@EqualsAndHashCode
@Introspected
class Book {

    @NonNull
    @NotBlank
    final String isbn

    @NonNull
    @NotBlank
    final String name

    Book(@NonNull @NotBlank String isbn,
         @NonNull @NotBlank String name) {
        this.isbn = isbn
        this.name = name
    }
}

Create an interface to map operations with bookinventory, and a Micronaut Declarative HTTP Client to consume it.

bookrecommendation/src/main/groovy/example/micronaut/BookInventoryOperations.groovy
package example.micronaut

import io.micronaut.core.annotation.NonNull
import reactor.core.publisher.Mono

import javax.validation.constraints.NotBlank

interface BookInventoryOperations {
    Mono<Boolean> stock(@NonNull @NotBlank String isbn)
}
bookrecommendation/src/main/groovy/example/micronaut/BookInventoryClient.groovy
package example.micronaut

import io.micronaut.core.annotation.NonNull
import io.micronaut.http.annotation.Consumes
import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client
import io.micronaut.retry.annotation.Recoverable
import reactor.core.publisher.Mono

import javax.validation.constraints.NotBlank

import static io.micronaut.http.MediaType.TEXT_PLAIN

@Client("http://localhost:8082") (1)
@Recoverable(api = BookInventoryOperations)

interface BookInventoryClient extends BookInventoryOperations {

    @Consumes(TEXT_PLAIN)
    @Get("/books/stock/{isbn}")
    Mono<Boolean> stock(@NonNull @NotBlank String isbn)
}
1 Use @Client to use declarative HTTP Clients

Create a Controller which injects both clients.

bookrecommendation/src/main/groovy/example/micronaut/BookController.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import org.reactivestreams.Publisher
import reactor.core.publisher.Flux

@CompileStatic
@Controller("/books") (1)
class BookController {

    private final BookCatalogueOperations bookCatalogueOperations
    private final BookInventoryOperations bookInventoryOperations

    BookController(BookCatalogueOperations bookCatalogueOperations,
                   BookInventoryOperations bookInventoryOperations) { (2)
        this.bookCatalogueOperations = bookCatalogueOperations
        this.bookInventoryOperations = bookInventoryOperations
    }

    @Get (3)
    Publisher<BookRecommendation> index() {
        Flux.from(bookCatalogueOperations.findAll())
                .flatMap(b -> Flux.from(bookInventoryOperations.stock(b.isbn))
                        .filter(Boolean::booleanValue)
                        .map(rsp -> b)
                ).map(book -> new BookRecommendation(book.name))
    }
}
1 The class is defined as a controller with the @Controller annotation mapped to the path /books
2 Clients are injected via constructor injection
3 The @Get annotation maps the index method to an HTTP GET request on /books

The previous controller returns a Publisher<BookRecommendation>. Create the BookRecommendation POJO:

bookrecommendation/src/main/groovy/example/micronaut/BookRecommendation.groovy
package example.micronaut

import groovy.transform.CompileStatic
import groovy.transform.EqualsAndHashCode
import io.micronaut.core.annotation.Introspected
import io.micronaut.core.annotation.NonNull

import javax.validation.constraints.NotBlank

@CompileStatic
@EqualsAndHashCode
@Introspected
class BookRecommendation {

    @NonNull
    @NotBlank
    final String name

    BookRecommendation(@NonNull @NotBlank String name) {
        this.name = name
    }
}

BookCatalogueClient and BookInventoryClient will fail to consume the bookcatalogue and bookinventory during the tests phase.

Using the @Fallback annotation you can declare a fallback implementation of a client that will be picked up and used once all possible retries have been exhausted

Create @Fallback alternatives in the test classpath.

bookrecommendation/src/test/groovy/example/micronaut/BookInventoryClientStub.groovy
package example.micronaut

import io.micronaut.context.annotation.Requires
import io.micronaut.core.annotation.NonNull
import io.micronaut.retry.annotation.Fallback
import jakarta.inject.Singleton
import reactor.core.publisher.Mono

import javax.validation.constraints.NotBlank

import static io.micronaut.context.env.Environment.TEST

@Requires(env = TEST) (1)
@Fallback
@Singleton
class BookInventoryClientStub implements BookInventoryOperations {

    @Override
    Mono<Boolean> stock(@NonNull @NotBlank String isbn) {
        if (isbn == "1491950358") {
            return Mono.just(true) (2)
        }
        if (isbn == "1680502395") {
            return Mono.just(false) (3)
        }
        Mono.empty() (4)
    }
}
1 Make this fallback class to be effective only when the Micronaut environment TEST is active
2 Here we arbitrarily decided that if everything else fails, that book’s stock would be true
3 Similarly, we decided that other book’s stock method would be false
4 Finally, any other book will have their stock method return an empty value
bookrecommendation/src/test/groovy/example/micronaut/BookCatalogueClientStub.groovy
package example.micronaut

import io.micronaut.context.annotation.Requires
import io.micronaut.retry.annotation.Fallback
import jakarta.inject.Singleton
import org.reactivestreams.Publisher
import reactor.core.publisher.Flux

import static io.micronaut.context.env.Environment.TEST

@Requires(env = TEST)
@Fallback
@Singleton
class BookCatalogueClientStub implements BookCatalogueOperations {

    @Override
    Publisher<Book> findAll() {
        Book buildingMicroservices = new Book("1491950358", "Building Microservices")
        Book releaseIt = new Book("1680502395", "Release It!")
        Flux.just(buildingMicroservices, releaseIt)
    }
}

Write a test:

bookrecommendation/src/test/groovy/example/micronaut/BookControllerSpec.groovy
package example.micronaut

import io.micronaut.http.HttpRequest
import io.micronaut.http.client.HttpClient
import io.micronaut.http.client.annotation.Client
import io.micronaut.test.extensions.spock.annotation.MicronautTest
import jakarta.inject.Inject
import io.micronaut.core.type.Argument
import spock.lang.IgnoreIf
import spock.lang.Specification

@MicronautTest
class BookControllerSpec extends Specification {

    @Inject
    @Client("/")
    HttpClient client

    @IgnoreIf({env['CI'] as boolean})
    void "retrieve books"() {
        when:
        List<BookRecommendation> books = client.toBlocking().retrieve(HttpRequest.GET("/books"), Argument.listOf(BookRecommendation))

        then:
        books.size() == 1
        books[0].name == "Building Microservices"
    }
}

Edit application.yml

bookrecommendation/src/main/resources/application.yml
micronaut:
  application:
    name: bookrecommendation (1)
1 Configure the application name. The name will be used later in the guide.

Modify the Application class to use dev as a default environment:

The Micronaut framework supports the concept of one or many default environments. A default environment is one that is only applied if no other environments are explicitly specified or deduced.

bookrecommendation/src/main/groovy/example/micronaut/Application.groovy
package example.micronaut

import groovy.transform.CompileStatic
import io.micronaut.runtime.Micronaut

import static io.micronaut.context.env.Environment.DEVELOPMENT

@CompileStatic
class Application {

    static void main(String[] args) {
        Micronaut.build(args)
                .mainClass(Application)
                .defaultEnvironments(DEVELOPMENT)
                .start()
    }
}

Create src/main/resources/application-dev.yml. The Micronaut framework applies this configuration file only for the dev environment.

bookrecommendation/src/main/resources/application-dev.yml
micronaut:
  server:
    port: 8080 (1)
1 Configure the application to listen on port 8080

Create a file named application-test.yml which is used in the test environment:

bookrecommendation/src/test/resources/application-test.yml
consul:
  client:
    registration:
      enabled: false

Run the unit test:

bookrecommendation
./mvnw test

4.4. Running the application

Run bookcatalogue microservice:

bookcatalogue
./mvnw mn:run
14:28:34.034 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 499ms. Server Running: http://localhost:8081

Run bookinventory microservice:

bookinventory
./mvnw mn:run
14:31:13.104 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 506ms. Server Running: http://localhost:8082

Run bookrecommendation microservice:

bookrecommendation
./mvnw mn:run
14:31:57.389 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 523ms. Server Running: http://localhost:8080

You can run a cURL command to test the whole application:

curl http://localhost:8080/books
[{"name":"Building Microservices"}]

5. Consul and the Micronaut framework

5.1. Install Consul via Docker

The quickest way to start using Consul is via Docker:

docker run -p 8500:8500 consul

The following screenshots show how to install/run Consul via Kitematic, a UI for Docker.

kitematic consul 1

Configure ports:

kitematic consul 2

5.2. Book Catalogue

Append to bookcatalogue service application.yml the following snippet:

bookcatalogue/src/main/resources/application.yml
consul:
  client:
    registration:
      enabled: true
    defaultZone: "${CONSUL_HOST:localhost}:${CONSUL_PORT:8500}"

This configuration registers a Micronaut application with Consul with minimal configuration. Discover a more complete list of configuration options at ConsulConfiguration.

5.3. Book Inventory

Modify the application.yml of the bookinventory application with the following snippet:

bookinventory/src/main/resources/application.yml
consul:
  client:
    registration:
      enabled: true
    defaultZone: "${CONSUL_HOST:localhost}:${CONSUL_PORT:8500}"

5.4. Book Recommendation

Append to bookrecommendation.application.yml the following snippet:

bookrecommendation/src/main/resources/application.yml
consul:
  client:
    registration:
      enabled: true
    defaultZone: "${CONSUL_HOST:localhost}:${CONSUL_PORT:8500}"

Modify BookInventoryClient and BookCatalogueClient to use the service id instead of a hardcoded URL.

bookrecommendation/src/main/groovy/example/micronaut/BookCatalogueClient.groovy
package example.micronaut

import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client
import io.micronaut.retry.annotation.Recoverable
import org.reactivestreams.Publisher

@Client(id = "bookcatalogue") (1)
@Recoverable(api = BookCatalogueOperations)

interface BookCatalogueClient extends BookCatalogueOperations {

    @Get("/books")
    Publisher<Book> findAll()
}
1 Use the configuration value micronaut.application.name used in bookcatalogue as service id.
bookrecommendation/src/main/groovy/example/micronaut/BookInventoryClient.groovy
package example.micronaut

import io.micronaut.core.annotation.NonNull
import io.micronaut.http.annotation.Consumes
import io.micronaut.http.annotation.Get
import io.micronaut.http.client.annotation.Client
import io.micronaut.retry.annotation.Recoverable
import reactor.core.publisher.Mono

import javax.validation.constraints.NotBlank

import static io.micronaut.http.MediaType.TEXT_PLAIN

@Client(id = "bookinventory") (1)
@Recoverable(api = BookInventoryOperations)

interface BookInventoryClient extends BookInventoryOperations {

    @Consumes(TEXT_PLAIN)
    @Get("/books/stock/{isbn}")
    Mono<Boolean> stock(@NonNull @NotBlank String isbn)
}
1 Use the configuration value micronaut.application.name used in bookinventory as service id.

5.5. Running the App

Run bookcatalogue microservice:

bookcatalogue
./gradlew run
14:28:34.034 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 499ms. Server Running: http://localhost:8081
14:28:34.084 [nioEventLoopGroup-1-3] INFO  i.m.d.registration.AutoRegistration - Registered service [bookcatalogue] with Consul

Run bookinventory microservice:

bookinventory
./gradlew run
14:31:13.104 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 506ms. Server Running: http://localhost:8082
14:31:13.154 [nioEventLoopGroup-1-3] INFO  i.m.d.registration.AutoRegistration - Registered service [bookinventory] with Consul

Run bookrecommendation microservice:

bookrecommendation
./gradlew run
14:31:57.389 [main] INFO  io.micronaut.runtime.Micronaut - Startup completed in 523ms. Server Running: http://localhost:8080
14:31:57.439 [nioEventLoopGroup-1-3] INFO  i.m.d.registration.AutoRegistration - Registered service [bookrecommendation] with Consul

Consul comes with a HTML UI. Open http://localhost:8500/ui in your browser.

You will see the services registered in Consul:

consului

You can run a cURL command to test the whole application:

curl http://localhost:8080/books
[{"name":"Building Microservices"}]

6. Next steps

Read more about Consul support in the Micronaut framework.

7. Help with the Micronaut Framework

Object Computing, Inc. (OCI) sponsored the creation of this Guide. A variety of consulting and support services are available.