Migrate to Micronaut 4 from Micronaut 3

In this guide, we'll look at using OpenRewrite to perform an automated migration from Micronaut 3.x to Micronaut 4.x

If you want to learn more about the process that went into developing these recipes, check out the Micronaut framework 4.0 release blog post.

Configuration

See various ways you can configure your project to run this recipe on the recipe reference page. This is also where you can find the full list of changes it will make.

Once you've configured your project, you're ready to execute the migration by running mvn rewrite:run or gradlew rewriteRun. After running the migration you can inspect the results with git diff (or equivalent), manually fix anything that wasn't able to be migrated automatically, and commit the results.

Before and After

Many javax packages have been updated to jakarta

These include:

• javax.annotation.*

• javax.persistence.*

• javax.validation.*

Before

import javax.annotation.PostConstruct;

import javax.persistence.GenerationType;

import javax.validation.constraints.NotBlank;
import javax.validation.Valid;
import javax.validation.constraints.NotNull;

// ...

After

import jakarta.annotation.PostConstruct;

import jakarta.persistence.GenerationType;

import jakarta.validation.constraints.NotBlank;
import jakarta.validation.Valid;
import jakarta.validation.constraints.NotNull;

// ...

Interface parameter updates

An HttpRequest type parameter has been added to some interfaces.

Before

import io.micronaut.http.HttpRequest;
import io.micronaut.security.authentication.AuthenticationProvider;
import io.micronaut.security.authentication.AuthenticationRequest;
import io.micronaut.security.authentication.AuthenticationResponse;
import org.reactivestreams.Publisher;
            
import java.io.Serializable;
            
public class AuthProvPass implements AuthenticationProvider, Serializable {
            
    @Override
    public Publisher<AuthenticationResponse> authenticate(HttpRequest<?> httpRequest,
                                                            AuthenticationRequest<?, ?> authenticationRequest) {
        return null;
    }
}

After

import io.micronaut.http.HttpRequest;
import io.micronaut.security.authentication.AuthenticationProvider;
import io.micronaut.security.authentication.AuthenticationRequest;
import io.micronaut.security.authentication.AuthenticationResponse;
import org.reactivestreams.Publisher;
            
import java.io.Serializable;
            
public class AuthProvPass implements AuthenticationProvider<HttpRequest<?>>, Serializable {
            
    @Override
    public Publisher<AuthenticationResponse> authenticate(HttpRequest<?> httpRequest,
                                                            AuthenticationRequest<?, ?> authenticationRequest) {
        return null;
    }
}

Various dependencies may be added or updated

These include:

• Micronaut Retry

• Micronaut Session

• Micronaut Websocket

• SnakeYaml

build.gradle

Before

plugins {
    id("io.micronaut.application") version "%s"
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("io.micronaut:micronaut-session")
}

After

plugins {
    id("io.micronaut.application") version "%s"
}

repositories {
    mavenCentral()
}

dependencies {
    implementation "io.micronaut:micronaut-retry"
    implementation "io.micronaut:micronaut-websocket"
    
    implementation("io.micronaut.session:micronaut-session")

    runtimeOnly "org.yaml:snakeyaml"
}

pom.xml

Before

<project>
    <groupId>com.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1</version>
    <parent>
        <groupId>io.micronaut.platform</groupId>
        <artifactId>micronaut-parent</artifactId>
        <version>%s</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-session</artifactId>
        </dependency>
    </dependencies>
</project>

After

<project>
    <groupId>com.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1</version>
    <parent>
        <groupId>io.micronaut.platform</groupId>
        <artifactId>micronaut-parent</artifactId>
        <version>%s</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-retry</artifactId>
        </dependency>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-websocket</artifactId>
        </dependency>
        <dependency>
            <groupId>io.micronaut.session</groupId>
            <artifactId>micronaut-session</artifactId>
        </dependency>
        <dependency>
            <groupId>org.yaml</groupId>
            <artifactId>snakeyaml</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>
</project>

withJansi configuration tag has been removed from logback.xml

Before

<configuration>  
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <withJansi>true</withJansi>
        <!-- encoders are assigned the type
            ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
        <encoder>
            <pattern>%cyan(%d{HH:mm:ss.SSS}) %gray([%thread]) %highlight(%-5level) %magenta(%logger{36}) - %msg%n</pattern>
        </encoder>
    </appender>
    <root level="info">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

After

<configuration>  
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <!-- encoders are assigned the type
            ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
        <encoder>
            <pattern>%cyan(%d{HH:mm:ss.SSS}) %gray([%thread]) %highlight(%-5level) %magenta(%logger{36}) - %msg%n</pattern>
        </encoder>
    </appender>
    <root level="info">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

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