How to configure REST properties in Java-only Camel Main? - apache-camel

Question

I'm working on a simple "hello-world" Camel3 (Camel version 3.4.3) REST API example with the following setup:
REST API is described in OpenAPI specification (Swagger v2.0)
The API spec is converted to Java DSL with camel-restdsl-swagger-plugin
Using Camel Main
100% Java (i.e. no XML)
The example below works as expected but I fail to set jetty port. Therefore on every run the web server runs on a random port. How do I set the port (e.g. to 8081) in the Java code ? It also seems to be possible to set the port in application.properties file. Example of that option is also appreciated.
// https://camel.apache.org/components/latest/others/main.html
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.main.Main;
import org.apache.camel.main.RestConfigurationProperties;
import rest.dsl.generated.Api101;
public class App {
public static void main(String[] args) throws Exception {
Main main = new Main();
// How do I set the rest properties ?
// The code below doesn't seem to have effect.
RestConfigurationProperties p = main.configure().rest()
.withComponent("jetty")
.withHost("localhost")
.withPort(8081)
;
main.configure().addConfiguration(p);
// The route generated by camel-restdsl-swagger-plugin
main.configure().addRoutesBuilder(
new Api101()
);
// The actual route.
main.configure().addRoutesBuilder(
new RouteBuilder() {
public void configure() {
from("direct:rest1")
.routeId("Rest1Route")
.log("START:")
.setBody(constant("{hello: \"Hello, World!\"}"))
.log("END:")
;
}
}
);
main.run(args);
}
}
Generated Api101 code:
package rest.dsl.generated;
import javax.annotation.Generated;
import org.apache.camel.builder.RouteBuilder;
/**
* Generated from Swagger specification by Camel REST DSL generator.
*/
#Generated("org.apache.camel.generator.swagger.PathGenerator")
public final class Api101 extends RouteBuilder {
/**
* Defines Apache Camel routes using REST DSL fluent API.
*/
public void configure() {
rest("/api101")
.get("/hello")
.description("Basic Hello World")
.to("direct:rest1");
}
}
Compilation & run example:
/tmp/openapi$ mvn clean compile exec:java
[INFO] Scanning for projects...
[INFO]
[INFO] ----------------------< com.stackoverflow:openapi >----------------------
[INFO] Building openapi 1.0
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) # openapi ---
[INFO] Deleting /tmp/openapi/target
[INFO]
[INFO] --- camel-restdsl-swagger-plugin:3.4.3:generate-with-dto (default) # openapi ---
[INFO] reading from /tmp/openapi/swagger.yaml
[INFO] Generating Camel DSL source in directory: /tmp/openapi/target/generated-sources/restdsl-swagger
[INFO] Generating DTO classes using io.swagger:swagger-codegen-maven-plugin:2.4.12
[INFO] reading from /tmp/openapi/swagger.yaml
[WARNING] Output directory does not exist, or is inaccessible. No file (.swagger-codegen-ignore) will be evaluated.
[WARNING] 'host' not defined in the spec. Default to 'localhost'.
[INFO] writing file /tmp/openapi/target/generated-sources/swagger/src/main/java/io/swagger/client/model/InlineResponse200.java
[WARNING] 'host' not defined in the spec. Default to 'localhost'.
[INFO]
[INFO] --- build-helper-maven-plugin:3.2.0:add-source (default) # openapi ---
[INFO] Source directory: /tmp/openapi/target/generated-sources/restdsl-swagger added.
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) # openapi ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) # openapi ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 3 source files to /tmp/openapi/target/classes
[INFO]
[INFO] --- exec-maven-plugin:3.0.0:java (default-cli) # openapi ---
[ App.main()] BaseMainSupport INFO Using properties from: classpath:application.properties;optional=true
[ App.main()] DefaultRoutesCollector INFO No additional Camel XML routes discovered from: classpath:camel/*.xml
[ App.main()] DefaultRoutesCollector INFO No additional Camel XML rests discovered from: classpath:camel-rest/*.xml
[ App.main()] AbstractCamelContext INFO Apache Camel 3.4.3 (camel-1) is starting
[ App.main()] AbstractCamelContext INFO StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
[ App.main()] JettyHttpComponent WARN JMX disabled in CamelContext. Jetty JMX extensions will remain disabled.
[ App.main()] log INFO Logging initialized #8774ms to org.eclipse.jetty.util.log.Slf4jLog
[ App.main()] Server INFO jetty-9.4.29.v20200521; built: 2020-05-21T17:20:40.598Z; git: 77c232aed8a45c818fd27232278d9f95a021095e; jvm 11.0.8+10-post-Ubuntu-0ubuntu120.04
[ App.main()] ContextHandler INFO Started o.e.j.s.ServletContextHandler#4d9f9a55{/,null,AVAILABLE}
[ App.main()] AbstractConnector INFO Started ServerConnector#157aa401{HTTP/1.1, (http/1.1)}{0.0.0.0:44267}
[ App.main()] Server INFO Started #8938ms
[ App.main()] InternalRouteStartupManager INFO Route: route1 started and consuming from: jetty:http://0.0.0.0:0/api101/hello
[ App.main()] InternalRouteStartupManager INFO Route: Rest1Route started and consuming from: direct://rest1
[ App.main()] AbstractCamelContext INFO Total 2 routes, of which 2 are started
[ App.main()] AbstractCamelContext INFO Apache Camel 3.4.3 (camel-1) started in 0.225 seconds
[ qtp1580225589-17] Rest1Route INFO START:
[ qtp1580225589-17] Rest1Route INFO END:
^C[ad #0 - CamelHangupInterceptor] DefaultMainShutdownStrategy INFO Received hang up - stopping the main instance.
[ App.main()] AbstractCamelContext INFO Apache Camel 3.4.3 (camel-1) is shutting down
[ad #0 - CamelHangupInterceptor] DefaultMainShutdownStrategy INFO Waiting for CamelContext to graceful shutdown, elapsed: 0.000 seconds
[ App.main()] DefaultShutdownStrategy INFO Starting to graceful shutdown 2 routes (timeout 45 seconds)
[el-1) thread #1 - ShutdownTask] DefaultShutdownStrategy INFO Route: Rest1Route shutdown complete, was consuming from: direct://rest1
[el-1) thread #1 - ShutdownTask] AbstractConnector INFO Stopped ServerConnector#157aa401{HTTP/1.1, (http/1.1)}{0.0.0.0:0}
[el-1) thread #1 - ShutdownTask] ContextHandler INFO Stopped o.e.j.s.ServletContextHandler#4d9f9a55{/,null,UNAVAILABLE}
[el-1) thread #1 - ShutdownTask] DefaultShutdownStrategy INFO Route: route1 shutdown complete, was consuming from: rest://get:/api101:/hello
[ App.main()] DefaultShutdownStrategy INFO Graceful shutdown of 2 routes completed in 0 seconds
[ App.main()] MainLifecycleStrategy INFO CamelContext: camel-1 has been shutdown, triggering shutdown of the JVM.
[ App.main()] AbstractCamelContext INFO Apache Camel 3.4.3 (camel-1) uptime 44.386 seconds
[ App.main()] AbstractCamelContext INFO Apache Camel 3.4.3 (camel-1) is shutdown in 0.037 seconds
/tmp/openapi$
As you can see from the above the web server is available in port 44267:
Started ServerConnector#157aa401{HTTP/1.1, (http/1.1)}{0.0.0.0:44267}
And can be successfully accessed:
$ sudo netstat -tulpn | grep /java
tcp6 0 0 :::44267 :::* LISTEN 16926/java
$ curl http://0.0.0.0:44267/api101/hello
{hello: "Hello, World!"}
$

Answer 1

I found an answer to my secondary question: this is the way to define the port with the properties:
$ cat src/main/resources/application.properties
camel.rest.port=8081
$
This is also the method how to set all the other configuration options mention in the documentation. Might be obvious for Java veterans, but it was not obvious for me.