How to replace tomcat with netty when using Webflux and Spring Cloud?

Question

Afte reading a few articles on SO about how to get a rid of Tomcat when using Webflux I am still unable to use Netty as a replacement of Tomcat.

Since it's a project involving different modules with a parent pom, etc. I will post here the link to the repo: https://github.com/Deviad/clarity

Let me know if there are more files, etc. that you would like me to copy-paste here in order to be compliant with SO policies.

The module I am interested into is clarity-transaction-dispatcher.

I think the problem has to do with the fact that Spring Cloud needs Tomcat at some level (some transitive dependencies) for my middle-ware (clarity-transaction-dispatcher) to talk with the Spring Cloud Configuration Server.

Therefore I am eager to know if there are any possible solutions to this issue.

Thank you.

I have tried excluding tomcat from some dependencies in maven, using the @Webflux annotation, excluding SpringMVC autoconfiguration. I have tried this as well: Spring boot enable/disable embedded tomcat with profile

Parent pom

<?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">
    <groupId>com.clarity</groupId>
    <modelVersion>4.0.0</modelVersion>
    <packaging>pom</packaging>
    <modules>
        <module>clarity-transaction-dispatcher</module>
        <module>clarity-eureka-server</module>
        <module>clarity-persistence</module>
        <module>clarity-config-server</module>
        <module>clarity-shared</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <artifactId>clarity</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <java.version>11</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        <org.mapstruct.version>1.3.0.Final</org.mapstruct.version>
        <jool.version>0.9.14</jool.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jersey</artifactId>
            <version>1.2.0.RELEASE</version>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework</groupId>
                    <artifactId>spring-web</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
<!--        <dependency>-->
<!--            <groupId>org.springframework.boot</groupId>-->
<!--            <artifactId>spring-boot-starter-web</artifactId>-->
<!--        </dependency>-->

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
            <version>${lombok.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-core</artifactId>
            <version>2.3.0.1</version>
        </dependency>
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jooq</groupId>
            <artifactId>jool</artifactId>
            <version>${jool.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <!-- Exclude the Tomcat dependency -->
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>an.awesome</groupId>
            <artifactId>pipelinr</artifactId>
            <version>0.2</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version> <!-- or newer version -->
                <configuration>
<!--                    <compilerVersion>11</compilerVersion> &lt;!&ndash; depending on your project &ndash;&gt;-->
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${org.mapstruct.version}</version>
                        </path>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                        <!-- other annotation processors -->
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Child pom of clarity-transaction-dispatcher

<?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>
    <parent>
        <groupId>com.clarity</groupId>
        <artifactId>clarity</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../</relativePath> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <spring-integration-kafka.version>3.1.4.RELEASE</spring-integration-kafka.version>
        <web3j.version>4.2.0</web3j.version>

    </properties>
    <artifactId>clarity-transaction-dispatcher</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>clarity-transaction-dispatcher</name>
    <description>This microservice dispatches transactions from a cryptocurrency server to Hyperledger</description>
    <packaging>jar</packaging>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.clarity</groupId>
                <artifactId>clarity</artifactId>
                <version>0.0.1-SNAPSHOT</version>
                <scope>import</scope>
                <type>pom</type>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>com.clarity</groupId>
            <artifactId>clarityshared</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-web</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-streams</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.integration</groupId>
            <artifactId>spring-integration-kafka</artifactId>
            <version>${spring-integration-kafka.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream-binder-kafka-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream-binder-kafka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream-binder-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-stream-schema</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>core</artifactId>
            <version>${web3j.version}</version>
        </dependency>
        <dependency>
            <groupId>com.aol.cyclops</groupId>
            <artifactId>cyclops-validation</artifactId>
            <version>7.2.4</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Main class of the same module:

package com.clarity.transactiondispatcher;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.web.reactive.config.EnableWebFlux;

import java.util.TimeZone;

@SpringBootApplication(exclude = {WebMvcAutoConfiguration.class})

@EnableWebFlux
public class TransactionDispatcherApplication implements InitializingBean {

    private void started() {
        TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
    }

    @Override
    public void afterPropertiesSet() {
        started();
    }

    public static void main(String... args) {
        new SpringApplicationBuilder(TransactionDispatcherApplication.class).web(WebApplicationType.REACTIVE).run(args);

    }
}

After excluding Tomcat from almost anywhere I could think of I still get the app running with Tomcat instead of with Netty.

its hard to know what is wrong with so many external libraries its kindof messy. can you pls remove `@EnableWebFlux` and the `exclude = {WebMvcAutoConfiguration.class}` — Toerktumlare, Jul 30 '19 at 18:57

score 2 · Answer 1 · answered Jul 31 '19 at 18:38

To develop a microservice with Spring-Boot and run with Netty server, require few dependencies.

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.projectreactor</groupId>
        <artifactId>reactor-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

and in the main class we need the @SpringBootApplication only.

Please make changes your parent and child pom.xml accordingly. There should not be any spring-boot-starter-web dependency at all.

score 0 · Answer 2 · answered Feb 14 '23 at 12:21

In my case Tomcat was in parent .pom, so I used <exclusion> tag like this:

<!-- Exclude Tomcat from dependencies -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Just insert it as extra dependency

How to replace tomcat with netty when using Webflux and Spring Cloud?

2 Answers2

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