Caused by: java.net.ConnectException: Connection refused: no further information: localhost/127.0.0.1:9300

I am developing a project from the link http://www.mkyong.com/spring-boot/spring-boot-spring-data-elasticsearch-example/ without any custom change yet.

My concerns is how we can run this project ? Do I need to install anything ?

org.elasticsearch.transport.ConnectTransportException: [][127.0.0.1:9300] connect_timeout[30s]
    at org.elasticsearch.transport.netty.NettyTransport.connectToChannelsLight(NettyTransport.java:967) ~[elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.transport.netty.NettyTransport.connectToNode(NettyTransport.java:933) ~[elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.transport.netty.NettyTransport.connectToNodeLight(NettyTransport.java:906) ~[elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.transport.TransportService.connectToNodeLight(TransportService.java:267) ~[elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.client.transport.TransportClientNodesService$SimpleNodeSampler.doSample(TransportClientNodesService.java:390) ~[elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.client.transport.TransportClientNodesService$NodeSampler.sample(TransportClientNodesService.java:336) [elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.client.transport.TransportClientNodesService.addTransportAddresses(TransportClientNodesService.java:187) [elasticsearch-2.4.4.jar:2.4.4]
    at org.elasticsearch.client.transport.TransportClient.addTransportAddress(TransportClient.java:243) [elasticsearch-2.4.4.jar:2.4.4]
    at com.mkyong.EsConfig.client(EsConfig.java:45) [classes/:na]
    at com.mkyong.EsConfig$$EnhancerBySpringCGLIB$$776c01dd.CGLIB$client$0(<generated>) [classes/:na]
    at com.mkyong.EsConfig$$EnhancerBySpringCGLIB$$776c01dd$$FastClassBySpringCGLIB$$c693023.invoke(<generated>) [classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) [spring-core-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:356) [spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at com.mkyong.EsConfig$$EnhancerBySpringCGLIB$$776c01dd.client(<generated>) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_131]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_131]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_131]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:467) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) [spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) [spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
    at com.mkyong.Application.main(Application.java:26) [classes/:na]
Caused by: java.net.ConnectException: Connection refused: no further information: localhost/127.0.0.1:9300

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>springboot-springdata-elasticsearch-example</artifactId>
    <packaging>jar</packaging>
    <url>https://www.mkyong.com</url>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.1.RELEASE</version>
    </parent>

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

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- Runtime, for Embedded Elasticsearch,
            comment this if connect to external elastic search server-->
        <dependency>
            <groupId>net.java.dev.jna</groupId>
            <artifactId>jna</artifactId>
            <scope>runtime</scope>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Answer

It is pretty clear that you have missed some or all of the steps in section 5.1 of the example that you are following. The last of them says that you must start the ElasticSearch instance. The evidence is that you haven’t done this (successfully). The instance would be listing for connections on port 9300, It isn’t, and that causes the OS to “refuse” the connection attempt by your client.

Prerequisite means that you must do them first.

Solution: follow the instructions.