Building micronaut microservices using microstartercli

Building Micronaut microservices using the Microstarter CLI is a streamlined process that involves leveraging a command-line interface to quickly scaffold and set up Micronaut projects. Below are the steps and essential information to get you started:

Prerequisites

Java Development Kit (JDK): Ensure you have JDK 8 or later installed.
Microstarter CLI: Install Microstarter CLI.

Installing Microstarter CLI

You can install Microstarter CLI using SDKMAN, a tool for managing parallel versions of multiple Software Development Kits:

bash

$ sdk install microstarter

Creating a Micronaut Project

Once Microstarter CLI is installed, you can create a new Micronaut project:

bash

$ microstarter create-app <project-name>

Replace <project-name> with your desired project name. This command scaffolds a new Micronaut application with the basic structure.

Project Structure

A typical Micronaut project created by Microstarter CLI includes:

src/main/java: The main application source code.
src/test/java: The test code.
src/main/resources: Configuration files.
build.gradle or pom.xml: The build file (Gradle or Maven).

Configuring Build Tool

Depending on your preference, you can choose Gradle or Maven as your build tool.

Using Gradle

Ensure build.gradle contains necessary dependencies:

groovy

plugins {

    id 'io.micronaut.application' version '1.0.0'

}
dependencies {

    annotationProcessor "io.micronaut:micronaut-inject-java"

    implementation "io.micronaut:micronaut-runtime"

    implementation "javax.annotation:javax.annotation-api"

    testImplementation "io.micronaut:micronaut-http-client"

}

micronaut { runtime "netty" testRuntime "junit5" processing { incremental true annotations "your.package.*" } }

Using Maven

Ensure pom.xml is properly configured:

xml

<dependencies>

    <dependency>

        <groupId>io.micronaut</groupId>

        <artifactId>micronaut-runtime</artifactId>

    </dependency>

    <dependency>

        <groupId>io.micronaut</groupId>

        <artifactId>micronaut-http-client</artifactId>

        <scope>test</scope>

    </dependency>

    <dependency>

        <groupId>javax.annotation</groupId>

        <artifactId>javax.annotation-api</artifactId>

    </dependency>

</dependencies>

<build> <plugins> <plugin> <groupId>io.micronaut.maven</groupId> <artifactId>micronaut-maven-plugin</artifactId> <version>1.0.0</version> </plugin> </plugins> </build>

Creating Controllers

Generate a controller using the CLI:

bash

$ microstarter create-controller com.example.HelloController

This command creates a controller class in src/main/java/com/example/HelloController.java.

Example Controller

Here’s an example of a simple controller:

java

package com.example;
import io.micronaut.http.annotation.Controller;

import io.micronaut.http.annotation.Get;
@Controller("/hello")

public class HelloController {

@Get("/") public String index() { return "Hello, World!"; } }

Running the Application

You can run the application using:

bash

$ ./gradlew run  # For Gradle

$ mvn mn:run     # For Maven

Testing

Micronaut applications typically use JUnit 5 for testing. Example test case:

java

package com.example;
import io.micronaut.http.client.HttpClient;

import io.micronaut.http.client.annotation.Client;

import io.micronaut.test.extensions.junit5.annotation.MicronautTest;

import org.junit.jupiter.api.Test;
import javax.inject.Inject;
import static org.junit.jupiter.api.Assertions.assertEquals;
@MicronautTest

public class HelloControllerTest {
    @Inject

    @Client("/")

    HttpClient client;

@Test void testHelloEndpoint() { String response = client.toBlocking().retrieve("/hello"); assertEquals("Hello, World!", response); } }

Deploying

Micronaut applications can be deployed to various platforms including:

Docker: Create a Dockerfile to containerize your application.
Kubernetes: Deploy the Docker container to a Kubernetes cluster.
Cloud Providers: Use providers like AWS, Google Cloud, or Azure.

Example Dockerfile

Dockerfile

FROM openjdk:11-jre-slim

COPY build/libs/your-application.jar /app.jar

ENTRYPOINT ["java", "-jar", "/app.jar"]

Build the Docker image:

bash

$ docker build -t your-application .

Run the Docker container:

bash

$ docker run -p 8080:8080 your-application

Conclusion

Using Microstarter CLI with Micronaut significantly reduces the boilerplate and setup time for building microservices. This guide should help you get started quickly with your first Micronaut microservice. For more advanced configurations and features, refer to the official Micronaut documentation.

Building micronaut microservices using microstartercli