問題描述：
項目采用spring boot 2.1版本，elasticsearch 5.*版本剥哑，啟動之后報錯

java.lang.IllegalArgumentException: Cannot register setting [http.netty.max_composite_buffer_components] twice
    at org.elasticsearch.common.settings.SettingsModule.registerSetting(SettingsModule.java:168)
    at org.elasticsearch.common.settings.SettingsModule.<init>(SettingsModule.java:74)
    at org.elasticsearch.client.transport.TransportClient.buildTemplate(TransportClient.java:140)
    at org.elasticsearch.client.transport.TransportClient.<init>(TransportClient.java:268)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:127)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:113)
    at org.elasticsearch.transport.client.PreBuiltTransportClient.<init>(PreBuiltTransportClient.java:103)
    at com.datayes.falcon.biz.config.TransportClientAutoConfig.getElasticsearchClient(TransportClientAutoConfig.java:73)

定位到出錯的代碼：

 Setting<?> existingSetting = nodeSettings.get(setting.getKey());
                if (existingSetting != null && (setting.isShared() == false || existingSetting.isShared() == false)) {
                    throw new IllegalArgumentException("Cannot register setting [" + setting.getKey() + "] twice");
                }
                nodeSettings.put(setting.getKey(), setting);

debug 定位發(fā)現(xiàn)是netty3和netty4的插件參數(shù)http.netty.max_composite_buffer_components不一致導(dǎo)致

{
  "key" : "http.netty.max_composite_buffer_components",
  "properties" : [
    "Shared",
    "NodeScope"
  ],
  "is_group_setting" : false,
  "default" : "-1"
}

# 此處少了屬性Shared
{
  "key" : "http.netty.max_composite_buffer_components",
  "properties" : [
    "NodeScope"
  ],
  "is_group_setting" : false,
  "default" : "69905"
}

但是之前采用spring boot 1.5.6版本是一直正常攒至，懷疑是架包的版本出現(xiàn)問題裆站，查看項目依賴信柿，發(fā)現(xiàn)果然如此：

image.png

修改為5.4.3版本即可（當(dāng)然將netty3切換成6.4.3版本應(yīng)該可以）

對比不同版本但两，主要是Netty4Plugin的默認(rèn)參數(shù)變化，如下圖

image.png

image.png