參考
https://dzone.com/articles/elasticsearch5-how-to-build-a-plugin-and-add-a-lis https://github.com/chrisshayan/es-changes-feed-plugin https://blog.csdn.net/qq_16164711/article/details/87872383 https://blog.gaiaproject.club/es-develop-plugin/ https://blog.51cto.com/13755625/2117995
Es的插件主要有如下幾種類型，參考
https://github.com/elastic/elasticsearch/tree/master/server/src/main/java/org/elasticsearch/plugins
API Extension Plugins API拓展插件：API extension plugins add new functionality to Elasticsearch by adding new APIs or features, usually to do with search or mapping.
Analysis Plugins 解析器插件：Analysis plugins extend Elasticsearch by adding new analyzers, tokenizers, token filters, or character filters to Elasticsearch.
Alerting Plugins 告警插件：Alerting plugins allow Elasticsearch to monitor indices and to trigger alerts when thresholds are breached.
Discovery Plugins 發現插件：Discovery plugins extend Elasticsearch by adding new discovery mechanisms that can be used instead of Zen Discovery.
Ingest Plugins 攝取插件：The ingest plugins extend Elasticsearch by providing additional ingest node capabilities.
Management Plugins 管理插件：Management plugins offer UIs for managing and interacting with Elasticsearch.
Mapper Plugins Mapper插件：Mapper plugins allow new field datatypes to be added to Elasticsearch.
Security Plugins 安全插件：Security plugins add a security layer to Elasticsearch.
Snapshot/Restore Repository Plugins 快照插件：Repository plugins extend the Snapshot/Restore functionality in Elasticsearch by adding repositories backed by the cloud or by distributed file systems:
Store Plugins 存儲插件：Store plugins offer alternatives to default Lucene stores.
ActionPlugin：An additional extension point for {@link Plugin}s that extends Elasticsearch's scripting functionality
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/ActionPlugin.java
CircuitBreakerPlugin 斷路器插件：An extension point for {@link Plugin} implementations to add custom circuit breakers
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/CircuitBreakerPlugin.java
ClusterPlugin 集羣插件：An extension point for {@link Plugin} implementations to customer behavior of cluster management.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/ClusterPlugin.java
EnginePlugin 引擎插件：A plugin that provides alternative engine implementations.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/EnginePlugin.java
ExtensiblePlugin 拓展插件：This class provides a callback for extensible plugins to be informed of other plugins which extend them.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/ExtensiblePlugin.java
IndexStorePlugin 索引存儲插件：A plugin that provides alternative directory implementations.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/IndexStorePlugin.java
NetworkPlugin 網絡插件：Plugin for extending network and transport related classes
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/NetworkPlugin.java
PersistentTaskPlugin 持續任務插件：Plugin for registering persistent tasks executors.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/PersistentTaskPlugin.java
ReloadablePlugin Reload插件：An extension point for {@link Plugin}s that can be reloaded. There is no clear definition about what reloading a plugin actually means. When a plugin is reloaded it might rebuild any internal members. Plugins usually implement this interface in order to reread the values of {@code SecureSetting}s and then rebuild any dependent internal members.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/ReloadablePlugin.java
RestCompatibilityPlugin Rest兼容性插件：An extension point for Compatible API plugin implementation.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/RestCompatibilityPlugin.java
ScriptPlugin 腳本插件：An additional extension point for {@link Plugin}s that extends Elasticsearch's scripting functionality.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/ScriptPlugin.java
SearchPlugin 搜索插件：Plugin for extending search time behavior.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/SearchPlugin.java
SystemIndexPlugin 系統索引插件：Plugin for defining system indices. Extends {@link ActionPlugin} because system indices must be accessed via APIs added by the plugin that owns the system index, rather than standard APIs.
https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/plugins/SystemIndexPlugin.java