Elasticsearch java client 사용시 java.lang.NoClassDefFoundError: org/elasticsearch/plugins/NetworkPlugin 발생하는 경우

아래와 같이 Elasticsearch java client 사용시 java.lang.NoClassDefFoundError: org/elasticsearch/plugins/NetworkPlugin 발생하거나 FiltersAggregator.KeyedFilter와 같은 API들을 찾을 수 없는 경우가 있다. 

java.lang.NoClassDefFoundError: org/elasticsearch/plugins/NetworkPlugin

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:763)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)

at java.net.URLClassLoader.access$100(URLClassLoader.java:73)

at java.net.URLClassLoader$1.run(URLClassLoader.java:368)

at java.net.URLClassLoader$1.run(URLClassLoader.java:362)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:361)

at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

at org.elasticsearch.transport.client.PreBuiltTransportClient.<clinit>(PreBuiltTransportClient.java:88)

at kr.bluewhale.elastic.broker.ElasticQueryThread.run(ElasticQueryThread.java:37)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)

at java.lang.Thread.run(Thread.java:745)

Caused by: java.lang.ClassNotFoundException: org.elasticsearch.plugins.NetworkPlugin

at java.net.URLClassLoader.findClass(URLClassLoader.java:381)

at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

... 16 more

그럴땐, org.elasticsearch.elasticsearch가 dependency에 정의되어있는지 확인해보자. 

<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>5.6.3</version>
</dependency>
<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>transport</artifactId>
    <version>5.6.3</version>
</dependency>