Configuring Camel-Spring for standalone Camel microservice in a multi-module Gradle project - spring

Question

Goal: Adapting Prototype microservice example from Ch7 of Camel in Action by Claus Ibsen into a Gradle multi-module project.
I followed the Spring Guide to 'Creating a Multi Module Project' among other resources.
Project Structure:
+ main-mm-build
|--+ src
|--+ main
|--+ java // Spring Boot microservice (A) in this tree
|--+ build.gradle
|--+ settings.gradle
|--+ contact-manager // standalone-camel-spring microservice (B)
|--+ src
|--+ main
|--+ java // standalone-camel-spring microservice (B) here
|--+ build.gradle
Got as far as:
microservice A (Spring Boot Rest controller) can invoke microservice B (standalone Camel exposing rest() on jetty, without Spring DI).
But what I really want is to use Spring DI (without Spring Boot) in microservice B.
After making changes for camel-spring I get an error.
It's probably mucked up Gradle config, but I could use some help.
main-mm-build/contact-manager$ ../gradlew build
main-mm-build/contact-manager$ java -jar build/libs/contact-manager-1.0.jar
.
.
.
Caused by: org.apache.camel.ResolveEndpointFailedException: Failed to resolve endpoint: rest://get:/contact-manager?consumerComponentName=jetty&consumes=application%2Fjson&outType=...dto.ContactDto%5B%5D&produces=application%2Fjson&routeId=route2 due to: null
at ...impl.engine.AbstractCamelContext.getEndpoint(AbstractCamelContext.java:801)
Caused by: java.lang.NullPointerException
at ...camel.spring.spi.ApplicationContextBeanRepository.lookupByNameAndType(Ap..j:45)
Root project Gradle file:
plugins {
id 'org.springframework.boot' version '2.3.1.RELEASE'
id 'io.spring.dependency-management' version '1.0.9.RELEASE'
id 'java'
}
sourceCompatibility = '11'
dependencies {
implementation 'org.springframework.boot:spring-boot-starter'
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.springframework.boot:spring-boot-starter-tomcat'
compileOnly 'org.projectlombok:lombok'
annotationProcessor 'org.projectlombok:lombok'
testImplementation('org.springframework.boot:spring-boot-starter-test') {
exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
}
}
test {
useJUnitPlatform()
}
allprojects {
group = 'el.cam'
repositories {
jcenter()
}
}
subprojects {
version = '1.0'
}
settings.gradle:
rootProject.name = 'main-mm-build'
include 'contact-manager'
Microservice B (contact-manager) build.gradle:
plugins {
id 'org.springframework.boot'
id 'io.spring.dependency-management'
id 'java'
id 'application'
}
sourceCompatibility = '11'
mainClassName = 'el.cam.contacts.ContactManagerApplication'
task fatJar(type: Jar) {
manifest {
attributes (
'Main-Class': mainClassName
)
}
baseName = 'contact-manager' + '-all'
from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
with jar
}
dependencies {
implementation(platform("org.springframework.boot:spring-boot-dependencies:2.3.1.RELEASE"))
implementation( platform("org.apache.camel:camel-spring-boot-dependencies:3.0.0-RC3") )
implementation 'org.springframework.boot:spring-boot-starter'
implementation 'org.apache.camel:camel-spring-boot-starter'
implementation 'org.apache.camel:camel-rest-starter'
implementation 'org.apache.camel:camel-jetty-starter'
implementation 'org.apache.camel:camel-jackson-starter'
implementation 'org.apache.camel:camel-swagger-java-starter'// '3.0.0-RC3'
compileOnly 'org.projectlombok:lombok'
annotationProcessor 'org.projectlombok:lombok'
testImplementation('org.springframework.boot:spring-boot-starter-test') {
exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
}
}
test {
useJUnitPlatform()
}
ContactManagerApplication.java ( I wonder if I'm configuring Spring Camel incorrectly here. All the examples I found were based on Spring boot autoconfiguration, so I just figured it out as I went.)
import el.cam.contacts.configuration.ContactManagerConfiguration;
import org.apache.camel.spring.Main;
public class ContactManagerApplication {
private static final Logger LOG = LoggerFactory.getLogger(ContactManagerApplication.class);
public static void main(String[] args) throws Exception {
Main main = new Main();
main.setApplicationContext(createSpringApplicationContext());
// main.addRoutesBuilder(contactManagerController); // DI using Spring Autowiring
main.run();
}
private static AbstractApplicationContext createSpringApplicationContext() {
AnnotationConfigApplicationContext appContext = new AnnotationConfigApplicationContext();
appContext.register(ContactManagerConfiguration.class);
appContext.refresh();
return appContext;
}
}
Configuration class:
#Configuration
#ComponentScan(basePackages = "el.cam.contacts")
public class ContactManagerConfiguration {
#Autowired
ContactManagerController contactManagerController;
#Bean
public CamelContext camelContext() throws Exception {
SpringCamelContext camelContext = new SpringCamelContext();
camelContext.addRoutes(contactManagerController);
camelContext.setPropertiesComponent(properties());
camelContext.addComponent("rest", rest());
camelContext.addComponent("rest-api", restApi());
camelContext.addComponent("jetty", jetty());
return camelContext;
}
#Bean
public PropertiesComponent properties() throws Exception {
PropertiesComponent properties = new PropertiesComponent();
properties.setLocation("classpath:application.properties");
return properties;
}
#Bean
public RestComponent rest() {
RestComponent rest = new RestComponent();
return rest;
}
#Bean
public RestApiComponent restApi() {
RestApiComponent restApi = new RestApiComponent();
return restApi;
}
#Bean
public JettyHttpComponent jetty() {
JettyHttpComponent jettyHttpComponent = new JettyHttpComponent9();
return jettyHttpComponent;
}
Controller class:
#Component
public class ContactManagerController extends RouteBuilder {
#Autowired
ContactManagerService contactManagerService;
#Override
public void configure() throws Exception {
// before Camel-Spring, was using this to bind serviceBean in camel registry
// getContext().getRegistry().bind("contactManagerService", new ContactManagerService());
// TODO using default. camel property sources not picking up application.properties!
restConfiguration("jetty").port("{{port:8282}}").contextPath("api")
.bindingMode(RestBindingMode.json)
.dataFormatProperty("disableFeatures", "FAIL_ON_EMPTY_BEANS")
.apiContextPath("api-doc")
.enableCORS(true);
// define the rest service
rest("/contact-manager").consumes("application/json").produces("application/json")
.get().outType(ContactDto[].class)
.to("bean:contactManagerService?method=getContacts(${header.contactType})")
;
}
}