Micronaut - jreact.com

https://micronaut.io/

Micronaut Tests

Features

A modern, JVM-based, full-stack framework for building modular, easily testable microservice and serverless applications.
Micronaut is built for the cloud. It provides built-in support for cloud-native features like service discovery, distributed configuration, and client-side load balancing.
It offers HTTP server and client APIs that are non-blocking, making them suitable for high-load microservices architectures.
Micronaut builds its dependency injection data at compile time.
Another feature is its first class support for reactive programming, for both clients and servers. The choice of a specific reactive implementation is left to the developer as both RxJava and Project Reactor are supported.
It supports multiple service discovery tools such as Eureka and Consul, and also works with different distributed tracing systems such as Zipkin and Jaeger.
It also provides support for creating AWS lambda functions, making it easy to create serverless applications.

Databases

We use:

MySQL

Local: MySQL

Docker: MySQL
service mysql stop

docker-compose.yaml

version: '3.1'

services:
   db_mysql:
      container_name: db_mysql
      image: mysql
      ports:
        - "3306:3306"
      restart: always
      environment:
        MYSQL_USER: admin
        MYSQL_PASSWORD: rNZzq5U37DqJlNe
        MYSQL_ROOT_PASSWORD: 4kDGQDYe4JxDjRd
      volumes:
        - /var/lib/mysqld:/var/lib/mysql

Usage Docker MySQL in db browser:

PostgreSQL

Local: PostgreSQL

Docker: PostgreSQL

systemctl stop postgresql

docker-compose.yaml

docker run -it --rm \
    -p 5432:5432 \
    -e POSTGRES_USER=dbuser \
    -e POSTGRES_PASSWORD=theSecretPassword \
    -e POSTGRES_DB=micronaut \
    postgres:11.5-alpine

First App

We are going to create a Micronaut app written in Java:

mn create-app zjc.example.micronaut.first.app.micronaut-first-app --build=maven --lang=java

The above code generates:

└── micronaut-first-app
    ├── aot-jar.properties
    ├── micronaut-cli.yml
    ├── mvnw
    ├── mvnw.bat
    ├── pom.xml
    ├── README.md
    └── src
        ├── main
        │   ├── java
        │   │   └── zjc
        │   │       └── example
        │   │           └── micronaut
        │   │               └── first
        │   │                   └── app
        │   │                       └── Application.java
        │   └── resources
        │       ├── application.properties
        │       └── logback.xml
        └── test
            └── java
                └── zjc
                    └── example
                        └── micronaut
                            └── first
                                └── app
                                    └── MicronautFirstAppTest.java

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>zjc.example.micronaut.first.app</groupId>
  <artifactId>micronaut-first-app</artifactId>
  <version>0.1</version>
  <packaging>${packaging}</packaging>

  <parent>
    <groupId>io.micronaut.platform</groupId>
    <artifactId>micronaut-parent</artifactId>
    <version>4.3.6</version>
  </parent>

  <properties>
    <packaging>jar</packaging>
    <jdk.version>17</jdk.version>
    <release.version>17</release.version>
    <micronaut.version>4.3.6</micronaut.version>
    <micronaut.runtime>netty</micronaut.runtime>
    <micronaut.aot.enabled>false</micronaut.aot.enabled>
    <micronaut.aot.packageName>zjc.example.micronaut.first.app.aot.generated</micronaut.aot.packageName>
    <exec.mainClass>zjc.example.micronaut.first.app.Application</exec.mainClass>
  </properties>

  <repositories>
    <repository>
      <id>central</id>
      <url>https://repo.maven.apache.org/maven2</url>
    </repository>
  </repositories>

  <dependencies>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-http-server-netty</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut.serde</groupId>
      <artifactId>micronaut-serde-jackson</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-http-client</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut.test</groupId>
      <artifactId>micronaut-test-junit5</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-engine</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <groupId>io.micronaut.maven</groupId>
        <artifactId>micronaut-maven-plugin</artifactId>
        <configuration>
          <configFile>aot-${packaging}.properties</configFile>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-enforcer-plugin</artifactId>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <!-- Uncomment to enable incremental compilation -->
          <!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->

          <annotationProcessorPaths combine.children="append">
            <path>
              <groupId>io.micronaut</groupId>
              <artifactId>micronaut-http-validation</artifactId>
              <version>${micronaut.core.version}</version>
            </path>
            <path>
              <groupId>io.micronaut.serde</groupId>
              <artifactId>micronaut-serde-processor</artifactId>
              <version>${micronaut.serialization.version}</version>
              <exclusions>
                <exclusion>
                  <groupId>io.micronaut</groupId>
                  <artifactId>micronaut-inject</artifactId>
                </exclusion>
              </exclusions>
            </path>
          </annotationProcessorPaths>
          <compilerArgs>
            <arg>-Amicronaut.processing.group=zjc.example.micronaut.first.app</arg>
            <arg>-Amicronaut.processing.module=micronaut-first-app</arg>
          </compilerArgs>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

Full description: http://jreact.com/index.php/2024/04/04/micronaut-first-app/

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