从发布/订阅到ElasticSearch的Apache光束流

Question

我正在编写一个ElasticSearch streaming管道，它从Google Cloud PubSub中读取消息，并将其写入java实例。目前，我使用的是direct runner，但计划在Google Cloud Dataflow上部署该解决方案。

首先，我编写了一个从PubSub读取和写入文本文件的管道，它可以正常工作。然后，我启动了ElasticSearch实例，这也可以正常工作。我用curl写了一些文档，很简单。

然后，当我尝试使用Beam的ElasticSearch连接器执行写操作时，我开始遇到一些错误。实际上，尽管我在pom.xml文件上添加了依赖项，但我还是得到了ava.lang.NoSuchMethodError: org.elasticsearch.client.RestClient.performRequest。

我所做的基本上是这样的：

messages.apply(
                        "TwoMinWindow",
                        Window.into(FixedWindows.of(new Duration(120*1000)))
                ).apply(
                        "ElasticWrite",
            ElasticsearchIO.write()
            .withConnectionConfiguration(
                             ElasticsearchIO.ConnectionConfiguration
                             .create(new String[]{"http://xxx.xxx.xxx.xxx:9200"}, "streaming_data", "string")
                             .withUsername("xxxx")
                             .withPassword("xxxxxxxx")
                             )
                );

使用DirectRunner，我可以连接到PubSub，但是当管道尝试连接ElasticSearch实例时，我得到了一个异常：

java.lang.NoSuchMethodError: org.elasticsearch.client.RestClient.performRequest(Ljava/lang/String;Ljava/lang/String;[Lorg/apache/http/Header;)Lorg/elasticsearch/client/Response;
    at org.apache.beam.sdk.util.UserCodeException.wrap (UserCodeException.java:34)
    at org.apache.beam.sdk.io.elasticsearch.ElasticsearchIO$Write$WriteFn$DoFnInvoker.invokeSetup (Unknown Source)
    at org.apache.beam.sdk.transforms.reflect.DoFnInvokers.tryInvokeSetupFor (DoFnInvokers.java:50)
    at org.apache.beam.runners.direct.DoFnLifecycleManager$DeserializingCacheLoader.load (DoFnLifecycleManager.java:104)
    at org.apache.beam.runners.direct.DoFnLifecycleManager$DeserializingCacheLoader.load (DoFnLifecycleManager.java:91)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache$LoadingValueReference.loadFuture (LocalCache.java:3528)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache$Segment.loadSync (LocalCache.java:2277)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache$Segment.lockedGetOrLoad (LocalCache.java:2154)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache$Segment.get (LocalCache.java:2044)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache.get (LocalCache.java:3952)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache.getOrLoad (LocalCache.java:3974)
    at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.cache.LocalCache$LocalLoadingCache.get (LocalCache.java:4958)
    at org.apache.beam.runners.direct.DoFnLifecycleManager.get (DoFnLifecycleManager.java:61)
    at org.apache.beam.runners.direct.ParDoEvaluatorFactory.createEvaluator (ParDoEvaluatorFactory.java:129)
    at org.apache.beam.runners.direct.ParDoEvaluatorFactory.forApplication (ParDoEvaluatorFactory.java:79)
    at org.apache.beam.runners.direct.TransformEvaluatorRegistry.forApplication (TransformEvaluatorRegistry.java:169)
    at org.apache.beam.runners.direct.DirectTransformExecutor.run (DirectTransformExecutor.java:117)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:511)
    at java.util.concurrent.FutureTask.run (FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:624)
    at java.lang.Thread.run (Thread.java:748)
Caused by: java.lang.NoSuchMethodError: org.elasticsearch.client.RestClient.performRequest(Ljava/lang/String;Ljava/lang/String;[Lorg/apache/http/Header;)Lorg/elasticsearch/client/Response;
    at org.apache.beam.sdk.io.elasticsearch.ElasticsearchIO.getBackendVersion (ElasticsearchIO.java:1348)
    at org.apache.beam.sdk.io.elasticsearch.ElasticsearchIO$Write$WriteFn.setup (ElasticsearchIO.java:1200)

我在pom.xml中添加的内容是：

    <dependency>
    <groupId>org.apache.beam</groupId>
    <artifactId>beam-sdks-java-io-google-cloud-platform</artifactId>
    <version>${beam.version}</version>
  </dependency>

    <!-- https://mvnrepository.com/artifact/org.elasticsearch.client/elasticsearch-rest-client -->
  <dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-client</artifactId>
    <version>${elastic.version}</version>
  </dependency>

我被这个问题困住了，我不知道如何解决它。如果我使用JestClient，我可以毫无问题地连接到ElasticSearch。

你有什么建议吗？

Answer 1

您正在使用没有performRequest(String, Header)方法的较新版本的RestClient。如果您查看the latest source code，您可以看到该方法现在采用Request，而在旧版本中采用there were methods that took Strings and Headers。这些方法被弃用，然后是removed from the code on September 1, 2018。

要么更改您的代码以使用更新的弹性搜索库，要么指定与您的代码兼容的旧版本的库(它需要在7.0.x之前，例如6.8.4)。