Can not extend SpringBootServletInitializer while using Apache-Camel Spring starter

Question

I am trying to create a deployable *.war from a Spring Boot application by following their documentation. I am having problem while extending SpringBootServletInitializer. It's giving me a compile time error saying The type org.springframework.web.WebApplicationInitializer cannot be resolved. It is indirectly referenced from required .class files. But in the Maven dependency directory I can clearly see SpringBootServletInitializer.class exists in spring-boot-1.5.10.RELEASE jar. It was downloaded as part of the camel-spring-boot-starter dependency.

My Main class

@SpringBootApplication
@EnableAutoConfiguration
public class SpringCamelApplication  extends SpringBootServletInitializer{

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

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

@Bean
public RestConfiguration restConfiguration()
{
    RestConfiguration restconfig=new RestConfiguration();
    restconfig.setPort(8081);
    restconfig.setComponent("restlet");
    //restconfig.setHost("localhost");
    restconfig.setContextPath("/api");
    restconfig.setBindingMode("auto");
    return restconfig;
}

}

My pom.xml

<modelVersion>4.0.0</modelVersion>
    <groupId>com.camel</groupId>
    <artifactId>spring-camel</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>spring-camel</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <camel.version>2.21.0</camel.version>
        <spring.version>2.0.0.RELEASE</spring.version>
        <start-class>com.camel.springcamel.SpringCamelApplication</start-class>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-spring-boot-starter</artifactId>
            <version>${camel.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-restlet</artifactId>
            <version>${camel.version}</version>
        </dependency>
    </dependencies>

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

Where am I going wrong here? I have noticed if I use spring-boot-starter-web dependency then this doesn't give me any error, but I already have camel-spring-boot-starter so I shouldn't need spring-boot-starter-web. Can anybody explain what is actually wrong here? Thanks in advance.

Answer 1

You need to update your camel version for Spring Boot 2 compatibility.

https://github.com/apache/camel/blob/master/components/camel-spring-boot/src/main/docs/spring-boot.adoc

Spring Boot 2 is supported since Camel 2.22 (summer 2018). Previous versions of Camel support Spring Boot 1.x only.

Also as of Spring Boot 2 spring-boot-starter-web is no longer a transitive dependency in Spring Starters due to the addition of spring-boot-starter-webflux for reactive impls of HTTP and WebSockets. It's up to third parties, or yourself, to decide on what implementation to pick.