Error starting Spring Boot with Tomcat 9.0.21

Question

Situation: I have an application implemented with Spring Boot and need to deploy to Tomcat (V9.0.21).

Problem: I managed the package . War normally and made the deploy. I start the application normally, but soon after the application is restarted, as the first time the start was successful, the second time gives errors of already used ports and the application is dropped.

Artifacts:

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
    </parent>
    <groupId>br.com.mensagem</groupId>
    <artifactId>mensagem</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>api-mensagem</name>
    <description>Websocket server de mensagens</description>
    <packaging>war</packaging>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.corundumstudio.socketio</groupId>
            <artifactId>netty-socketio</artifactId>
            <version>1.7.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
            <version>3.0.0</version>
        </dependency>


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

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Springbootapplication.java

package br.com.mensagemwebsocket;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class MensagemApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(MensagemApplication.class, args);
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(MensagemApplication.class);
    }
}

application properties

spring.thymeleaf.cache=false
#server.port=8088

#server.address=192.168.0.45
# ===============================
# = DATA SOURCE
# ===============================

## DEV
# Connection url for the database "dbacacio"
spring.datasource.url = jdbc:mysql://localhost:3306/dbacacio

# Username and password
spring.datasource.username = root

# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1

# ===============================
# = JPA / HIBERNATE
# ===============================

# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager).

# Show or not log for each sql query
spring.jpa.show-sql = true

# Hibernate ddl auto (create, create-drop, update): with "update" the database
# schema will be automatically updated accordingly to java entities found in
# the project
#spring.jpa.hibernate.ddl-auto = update

# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy

# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

Answer 1

I found the solution... wow, good, after analyzing codes, to inspire in your comments I found the problem.

Had a class Serveletinitializer extending Springbootservletinitializer.

There was the problem. I removed this class and everything went beautiful as it should be. Strange is that the Eclipse did not give this error, but okay.

I had the intuition to remove this class, I do not know why I put, when I saw this part of the log presented in the console.

Thank you all for your suggestions!!!

  [1]: https://i.stack.imgur.com/yTJct.jpg