Java application deployment with Docker and Kubernetes

README.MD

#Java application deployment with Docker and Kubernetes

Stop the service

POST http://localhost:8080/actuator/shutdown

Get environment details

GET http://localhost:8080/actuator/info curl http://localhost:80/actuator/info

Build the image

• cd [pom.xml folder]
• mvn clean package
• docker image build -t /k8s-demo:1.0 .

Run the image

Creates and run the container

docker container run -d --name k8s-demo -p 8080:8080 mrocabado/k8s-demo:1.0

Starts the container

docker container start k8s-demo

Clean up

docker container rm $(docker container ls -aq) -f

K8sDemoApplication.java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class K8sDemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(K8sDemoApplication.class, args);
	}
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.3.2.RELEASE</version>
		<relativePath/>
	</parent>
	<groupId>com.mindwaresrl</groupId>
	<artifactId>k8s-demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>k8s-demo</name>
	<description>K8s Demo project</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
		    <groupId>org.springframework.boot</groupId>
		    <artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
		<dependency>
		  <groupId>com.github.oshi</groupId>
		  <artifactId>oshi-core</artifactId>
		  <version>5.2.2</version>
		</dependency>				
		<dependency>
		    <groupId>org.springframework.boot</groupId>
		    <artifactId>spring-boot-devtools</artifactId>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<scope>provided</scope>
		</dependency>		
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

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

</project>

SystemInfoContributor.java

package com.example.demo.k8s;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.springframework.boot.actuate.info.Info.Builder;
import org.springframework.boot.actuate.info.InfoContributor;
import org.springframework.stereotype.Component;

import oshi.SystemInfo;
import oshi.hardware.HardwareAbstractionLayer;
import oshi.hardware.NetworkIF;
import oshi.software.os.OperatingSystem;

@Component
public class SystemInfoContributor implements InfoContributor {
	
	private static SystemInfo systemInfo = new SystemInfo();

	@Override
	public void contribute(Builder builder) {
		HardwareAbstractionLayer hal = systemInfo.getHardware();
		OperatingSystem os = systemInfo.getOperatingSystem();
		List<NetworkIF> networkInterfaces =  hal.getNetworkIFs();
		
		Map<String, Object> details = new HashMap<>();
		details.put("processor", String.format("Physical: %d, Logical: %d", hal.getProcessor().getPhysicalProcessorCount(), hal.getProcessor().getLogicalProcessorCount() ));
		details.put("memory", hal.getMemory().toString());
		details.put("network interfaces", buildReport(networkInterfaces));
		details.put("network parameters", os.getNetworkParams().toString());
				
        builder.withDetails(details);
	}

	private String buildReport(List<NetworkIF> networkInterfaces) {
		if (networkInterfaces.isEmpty()) {
			return "no network interfaces found";
		}
		
		return networkInterfaces.stream()
						 .filter(networkIF -> networkIF.getIPv4addr().length>0)
						 .map( this::buildReport)
						 .collect(Collectors.joining(" | "));
	}
	
	private String buildReport(NetworkIF networkIF) {
		String ips = Arrays.asList(networkIF.getIPv4addr()).stream().collect(Collectors.joining(" "));
		return String.format("%s: %s", networkIF.getName(), ips);
	}

}