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spring-core-example

README.adoc

Spring Core Example for Nginx-Clojure

This example project is used to demo how to use spring dependency injection with Nginx-Clojure java rewrite handler.

Step 1. Add Nginx JVM Init Handler

In this example we use Nginx JVM initialization handler to start the spring application.

nginx.conf
jvm_handler_type 'java';

jvm_init_handler_name 'nginx.clojure.spring.core.example.NginxJvmInitHandler';
NginxJvmInitHandler
package nginx.clojure.spring.core.example;

import java.io.IOException;
import java.util.Map;

import nginx.clojure.java.NginxJavaRingHandler;

public class NginxJvmInitHandler implements NginxJavaRingHandler {

	public NginxJvmInitHandler() {
		SpringExampleApplication.main(new String[0]);
	}

	@Override
	public Object[] invoke(Map<String, Object> request) throws IOException {
		return null;
	}

}

The spring application java code need not be changed for Nginx-Clojure.

SpringExampleApplication
package nginx.clojure.spring.core.example;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class SpringExampleApplication {

	public SpringExampleApplication() {
	}

	public static void main(String[] args) {
		ApplicationContext context = new AnnotationConfigApplicationContext("nginx.clojure.spring.core.example");
	}

}

Step 2. Add Spring Application Context Aware

SpringApplicationContextAware is used to get spring application context gracefully without need to change existed code.

SpringApplicationContextAware
package nginx.clojure.spring.core.example;

import java.util.concurrent.CountDownLatch;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class SpringApplicationContextAware implements ApplicationContextAware {

	private static ApplicationContext applicationContext;

	private static CountDownLatch countDownLatch = new CountDownLatch(1);

	public static ApplicationContext getApplicationContext() {
		try {
			countDownLatch.await();
		} catch (InterruptedException e) {
			throw new RuntimeException("SpringApplicationContextAware countDownLatch interrupted error", e);
		}
		return applicationContext;
	}

	public SpringApplicationContextAware() {
	}

	@Override
	public void setApplicationContext(ApplicationContext ctx) throws BeansException {
		applicationContext = ctx;
		countDownLatch.countDown();
	}

}

Step 3. Use Wrapper to Access Spring-styled Handlers

nginx.conf
set $proxy_target "";

location /hello {
    rewrite_handler_type java;
    rewrite_handler_name 'nginx.clojure.spring.core.example.NginxSpringHandlerWrapper';
    rewrite_handler_property 'spring.realHandler' 'myRewriteHandler';
    rewrite_handler_property 'spring.prefetched.vars' 'remote_addr,remote_port';
    proxy_pass http://$proxy_target;
}
NginxSpringHandlerWrapper
package nginx.clojure.spring.core.example;

import java.io.IOException;
import java.util.Map;

import nginx.clojure.Configurable;
import nginx.clojure.java.NginxJavaRingHandler;

public class NginxSpringHandlerWrapper implements NginxJavaRingHandler, Configurable {

	private NginxJavaRingHandler realHandler;

	private String[] prefetchedVars;


	public NginxSpringHandlerWrapper() {

	}

	@Override
	public void config(Map<String, String> properties) {
		String name = properties.get("spring.realHandler");
		realHandler = (NginxJavaRingHandler)SpringApplicationContextAware.getApplicationContext().getBean(name);
		prefetchedVars = properties.get("spring.prefetched.vars").split(",");
	}

	@Override
	public Object[] invoke(Map<String, Object> request) throws IOException {
		return realHandler.invoke(request);
	}

	@Override
	public String[] variablesNeedPrefetch() {
		return prefetchedVars;
	}


}
NginxSpringRewriteHandler
package nginx.clojure.spring.core.example;

import java.io.IOException;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import nginx.clojure.MiniConstants;
import nginx.clojure.java.ArrayMap;
import nginx.clojure.java.Constants;
import nginx.clojure.java.NginxJavaRequest;
import nginx.clojure.java.NginxJavaRingHandler;


@Service("myRewriteHandler")
public class NginxSpringRewriteHandler implements NginxJavaRingHandler {

	@Autowired
	private ProxyTargetComputeService proxyTargetComputeService;

	public NginxSpringRewriteHandler() {

	}

	@Override
	public Object[] invoke(Map<String, Object> r) throws IOException {
		NginxJavaRequest req = (NginxJavaRequest)r;
		String target = proxyTargetComputeService.computeTarget(req.getVariable("remote_addr"), req.getVariable("remote_port"));
		req.setVariable("proxy_target", target);
		return Constants.PHASE_DONE;
	}

}
ProxyTargetComputeService
package nginx.clojure.spring.core.example;

import org.springframework.stereotype.Service;

@Service("proxyTargetComputeService")
public class ProxyTargetComputeService {

	public String computeTarget(String ip, String port) {
		int m = (ip + ":" + port).hashCode() % 2;
		return m == 0 ? "127.0.0.1:8081" : "127.0.0.1:8082";
	}
}

How to Run

git clone https://github.com/nginx-clojure/nginx-clojure
cd nginx-clojure/example-projects/spring-core-example

## use mvn pakage to get spring-core-example-0.0.1-jar-with-dependencies.jar
mvn package


cd nginx-spring-work-dir
mkdir logs temp
wget https://sourceforge.net/projects/nginx-clojure/files/nginx-clojure-0.5.1.tar.gz
tar -zxvf nginx-clojure-0.5.1.tar.gz nginx-clojure-0.5.1/nginx-linux-x64
mv nginx-clojure-0.5.1/nginx-linux-x64 nginx
./nginx
curl -v http://localhost:8080/hello
> GET /hello HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.64.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Mon, 25 Nov 2019 03:21:11 GMT
< Content-Type: text/html
< Content-Length: 20
< Connection: keep-alive
< Server: nginx-clojure/0.5.1
Hello! 2