[CAMEL-16235] camel-servlet-starter does not ServletComponent

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.7.0
• Fix Version/s: 3.9.0
• Component/s: camel-servlet
• Estimated Complexity: Unknown
• Assignee: Claus Ibsen
• Reporter: Siva Kuna
• Created: 18/Feb/21 21:42
• Updated: 17/Mar/21 10:51
• Resolved: 17/Mar/21 10:51

Description

Below is my dependency configuration in build.gradle script of my project

ext {
    versions = [
        camel : "3.5.0",
        springBoot : "2.3.0.RELEASE",
    ]
}

dependencies {
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version: versions.springBoot    
    compile group: 'org.apache.camel.springboot', name: 'camel-servlet-starter', version: versions.camel    
    compile group: 'javax.inject', name: 'javax.inject', version: '1'    

    compile group: 'org.apache.camel', name: 'camel-core',          version: versions.camel
    compile group: 'org.apache.camel', name: 'camel-http',          version: versions.camel
    compile group: 'org.apache.camel', name: 'camel-jackson',       version: versions.camel
    compile group: 'org.apache.camel', name: 'camel-rest-openapi',  version: versions.camel
    compile group: 'org.apache.camel', name: 'camel-aws2-s3',       version: versions.camel    
    compile group: 'org.apache.camel', name: 'camel-swagger-java',  version: versions.camel    
}

 Below is a RouteBuilder class

public class MyRouteBuilder extends RouteBuilder {
    @Override
    public void configure() throws Exception {
        this.restConfiguration().bindingMode(RestBindingMode.json)
            .clientRequestValidation(true).apiProperty("api.title", "MyAPI") 
            .apiProperty("api.version", "1.0").apiProperty("cors", "true")
            .apiContextPath("api-doc");
    }
}

 

When I start the Spring Boot application the camel-servlet-starter starts the ServletComponent and I can access the api-doc URL. But the same code fails when I upgrade the Camel version to 3.7.0.

This is what I discovered when I tried to understand why camel-servlet-starter starts in 3.5.0 and fails in 3.7.0

Below is the definition of Servlet Component Bean in org.apache.camel.component.servlet.springboot.ServletComponentAutoConfiguration class of camel-servlet-starter-3.5.x

@Lazy    
@Bean(name = "servlet-component")    
@ConditionalOnMissingBean(ServletComponent.class)    
public ServletComponent configureServletComponent() throws Exception {          
    ServletComponent component = new ServletComponent();        
    component.setCamelContext(camelContext);
}

When Spring starts Camel routes, it asks RestApiEndpoint to create REST API Consumer and Spring initializes the Servlet Component by invoking ServletComponentAutoConfiguration.configureServletComponent(). 

This is changed in camel-servlet-starter-3.7.x

@Lazy 
@Bean 
public ComponentCustomizer configureServletComponent() { 
    return new ComponentCustomizer() { 
        @Override 
        public void configure(String name, Component target) {  
            CamelPropertiesHelper.copyProperties(camelContext, configuration, target); 
        } 

        @Override 
        public boolean isEnabled(String name, Component target) { 
            return HierarchicalPropertiesEvaluator.evaluate(applicationContext,   
                         "camel.component.customizer", 
                          "camel.component.servlet.customizer") 
                    && target instanceof ServletComponent; } 
        }; 
}

Spring fails to start CamelContext with the below exception stack trace:

org.apache.camel.FailedToStartRouteException: Failed to start route route1 because of null 
  at org.apache.camel.impl.engine.RouteService.warmUp(RouteService.java:122) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.InternalRouteStartupManager.doWarmUpRoutes(InternalRouteStartupManager.java:270) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.InternalRouteStartupManager.safelyStartRouteServices(InternalRouteStartupManager.java:157) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.InternalRouteStartupManager.doStartOrResumeRoutes(InternalRouteStartupManager.java:115) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.AbstractCamelContext.doStartCamel(AbstractCamelContext.java:2889) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.AbstractCamelContext.doStartContext(AbstractCamelContext.java:2702) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.AbstractCamelContext.doStart(AbstractCamelContext.java:2665) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.spring.boot.SpringBootCamelContext.doStart(SpringBootCamelContext.java:43) ~[camel-spring-boot-3.7.0.jar:3.7.0] 
  at org.apache.camel.support.service.BaseService.start(BaseService.java:115) ~[camel-api-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.AbstractCamelContext.start(AbstractCamelContext.java:2431) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.spring.SpringCamelContext.start(SpringCamelContext.java:130) ~[camel-spring-3.7.0.jar:3.7.0] 
  at org.apache.camel.spring.SpringCamelContext.onApplicationEvent(SpringCamelContext.java:167) ~[camel-spring-3.7.0.jar:3.7.0] 
  at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:203) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:196) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:161) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:426) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:383) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:945) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:591) ~[spring-context-5.3.1.jar:5.3.1] 
  at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.0.jar:2.4.0] 
  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) ~[spring-boot-2.4.0.jar:2.4.0] 
  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.4.0.jar:2.4.0] 
  at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) ~[spring-boot-2.4.0.jar:2.4.0] 
  at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) ~[spring-boot-2.4.0.jar:2.4.0] 
  at com.guidewire.surepath.document.management.box.DocumentManagementBoxApplication.main(DocumentManagementBoxApplication.java:16) ~[main/:na]
Caused by: java.lang.IllegalStateException: Cannot find RestApiConsumerFactory in Registry or as a Component to use 
  at org.apache.camel.component.rest.RestApiEndpoint.createConsumer(RestApiEndpoint.java:278) ~[camel-rest-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.DefaultRoute.addServices(DefaultRoute.java:575) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.DefaultRoute.onStartingServices(DefaultRoute.java:160) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.RouteService.doWarmUp(RouteService.java:150) ~[camel-base-engine-3.7.0.jar:3.7.0] 
  at org.apache.camel.impl.engine.RouteService.warmUp(RouteService.java:120) ~[camel-base-engine-3.7.0.jar:3.7.0]

Spring starts CamelContext successfully if I register the servlet component in the RouteBuilder class

Below is a RouteBuilder class

public class MyRouteBuilder extends RouteBuilder {
    @Override
    public void configure() throws Exception {
        this.restConfiguration().bindingMode(RestBindingMode.json)
            .clientRequestValidation(true).apiProperty("api.title", "MyAPI") 
            .apiProperty("api.version", "1.0").apiProperty("cors", "true")
            .component("servlet")             
            .apiContextPath("api-doc");
    }
}

 

Are developers mandated to register ServletComponent in the RouteBuilder class?