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Elasticsearch Ingest Pipelines

1. 前言

在将第三方数据源的数据导入到Elasticsearch中时,原始数据长什么样,索引后的文档就是什么样。文档数据结构不统一,导致后续数据分析时变得麻烦,以往需要额外写一个中间程序来读取原始数据,转换加工后再写入到Elasticsearch,比较麻烦,于是官方推出了Ingest pipeline。

Ingest pipeline 允许文档在被索引之前对数据进行预处理,将数据加工处理成我们需要的格式,例如删除或增加一些字段等。有了Ingest pipeline,就不需要我们再额外开发中间程序对数据进行加工转换等操作了,全权交给Elasticsearch即可。

2. 创建Ingest pipeline

Pipeline 由一系列处理器 Processor 组成,每个Processor按照顺序执行,对传入的文档进行加工处理,Elasticsearch再将加工后的文档添加到索引中。

默认情况下,每个节点都具备ingest能力,即文档预处理的能力。如果要预处理大量的文档,建议开启专门的ingest节点,配置如下:

node.roles: [ ingest ]

可以通过Elasticsearch提供的「_ingest/pipeline」端点来创建Ingest pipeline,如下示例,创建了一个名为“test-pipeline”的pipeline,它由三个Processor组成:lowercase负责将字段值改为小写、remove负责删除给定字段、rename负责重命名给定字段。

PUT _ingest/pipeline/test-pipeline
{
  "description": "测试pipeline",
  "processors": [
    {
      "lowercase": {
        "field": "title"
      },
      "remove": {
        "field": "extended_data"
      },
      "rename": {
        "field": "field_a",
        "target_field": "field_b"
      }
    }
  ]
}

然后,我们就可以通过Elasticsearch提供的模拟API,来测试我们的Pipelline,如下示例:

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "title": "我是TITLE",
        "extended_data": "我是扩展数据",
        "field_a": "我是要rename的field"
      }
    }
  ]
}

Pipeline返回的结果符合我们的预期,字段title的值英文部分改为了等效的小写、extended_data字段被删除了、field_a被重命名为field_b。

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "title": "我是title",
          "field_b": "我是要rename的field"
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:21:20.521194Z"
        }
      }
    }
  ]
}

3. 内置的Processor

截止Elasticsearch8.13版本,官方内置了40多个的Processor供我们使用,如下是部分Processor示例:

这里介绍几个常用的,其它参考官方文档即可。

append Processor:如果字段已经存在并且是一个数组,则向现有数组追加一个或多个值。

如下示例,如果文档存在tags字段并且是数组,则会自动追加给定的两个tag

PUT _ingest/pipeline/test-pipeline
{
  "processors": [
    {
      "append": {
        "field": "tags",
        "value": ["年度十佳","Top100"]
      }
    }
  ]
}

测试结果

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "tags":["热门"]
      }
    }
  ]
}

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "tags": [
            "热门",
            "年度十佳",
            "Top100"
          ]
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:31:23.089093Z"
        }
      }
    }
  ]
}

bytes Processor:将人类可读的字节值(例如1KB)转换为整型字节值(例如1024),如果是数组则转换所有成员。

如下示例,字段memory将会由人类可读的字符串转换为整型字节值

PUT _ingest/pipeline/test-pipeline
{
  "processors": [
    {
      "bytes": {
        "field": "memory"
      }
    }
  ]
}

测试结果

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "memory":"132MB"
      }
    }
  ]
}

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "memory": 138412032
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:35:07.233976Z"
        }
      }
    }
  ]
}

convert Processor:将文档中的某个字段转换为给定的数据类型,例如将字符串转换为布尔类型。数据类型转换不能随意配置,否则会报错,支持的类型有:integer、long、float、double、string、boolean、ip、auto。

如下示例,将字符串转换为布尔类型

PUT _ingest/pipeline/test-pipeline
{
  "processors": [
    {
      "convert": {
        "field": "deleted",
        "type": "boolean"
      }
    }
  ]
}

测试结果

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "deleted":"false"
      }
    }
  ]
}

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "deleted": false
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:40:42.066717Z"
        }
      }
    }
  ]
}

date Processor:从文档中的某个字段中解析时间,并将其作为文档的时间戳,默认时间戳的字段名为”@timestamp“。

如下示例,我们将publish_time作为文档的时间戳:

PUT _ingest/pipeline/test-pipeline
{
  "processors": [
    {
      "date": {
        "field": "publish_time",
        "formats": ["yyyy-MM-dd HH:mm:ss"]
      }
    }
  ]
}

测试结果:

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "publish_time":"2024-01-01 00:00:00"
      }
    }
  ]
}

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "publish_time": "2024-01-01 00:00:00",
          "@timestamp": "2024-01-01T00:00:00.000Z"
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:44:28.383089Z"
        }
      }
    }
  ]
}

最后介绍一个功能强大的Processor:script,通过内联的自定义脚本来操作文档,使用起来相当灵活。

如下示例,Processor将从content字段中提取品牌、商品标题和价格,并移除掉content字段。

PUT _ingest/pipeline/test-pipeline
{
  "processors": [
    {
      "script": {
        "lang": "painless",
        "source": """
        String[] splits = ctx['content'].splitOnToken(',');
        ctx['brand'] = splits[0];
        ctx['title'] = splits[1];
        ctx['price'] = Integer.parseInt(splits[2]);
        ctx.remove('content');
        """
      }
    }
  ]
}

测试结果

POST _ingest/pipeline/test-pipeline/_simulate
{
  "docs": [
    {
      "_source": {
        "content":"小米,小米汽车SU7,214900"
      }
    }
  ]
}

{
  "docs": [
    {
      "doc": {
        "_index": "_index",
        "_version": "-3",
        "_id": "_id",
        "_source": {
          "title": "小米汽车SU7",
          "brand": "小米",
          "price": 214900
        },
        "_ingest": {
          "timestamp": "2024-04-15T07:58:44.134495Z"
        }
      }
    }
  ]
}

4. 应用Ingest pipeline

Ingest pipeline创建好以后,主要有四类应用场景。

先创建一个名为”set-last-update-time-pipeline“的pipeline,它的目的是给文档设置一个最后修改的时间戳。

PUT _ingest/pipeline/set-last-update-time-pipeline
{
  "processors": [
    {
      "set": {
        "field": "last_update_time",
        "value": "{{{_ingest.timestamp}}}"
      }
    }
  ]
}

4.1 索引时指定pipeline

可以在索引文档时指定Pipeline,文档写入前会先经过管道的预处理。

下面是没指定Pipeline时写入文档和索引结果

POST test-index/_doc/1
{
  "title":"new doc"
}

{
  "_index": "test-index",
  "_id": "1",
  "_version": 1,
  "_seq_no": 0,
  "_primary_term": 1,
  "found": true,
  "_source": {
    "title": "new doc"
  }
}

下面是指定Pipeline时索引文档和索引结果,发现文档自动添加了last_update_time字段。

POST test-index/_doc/1?pipeline=set-last-update-time-pipeline
{
  "title":"new doc"
}

{
  "_index": "test-index",
  "_id": "1",
  "_version": 1,
  "_seq_no": 0,
  "_primary_term": 1,
  "found": true,
  "_source": {
    "title": "new doc",
    "last_update_time": "2024-04-15T08:11:50.448923Z"
  }
}

4.2 更新时指定pipeline

在更新文档时,也可以指定Pipeline对要更新的文档执行预处理操作。

如下示例,先索引两个文档

POST test-index/_doc/1
{
  "title":"new doc1"
}
POST test-index/_doc/2
{
  "title":"new doc2"
}

然后利用”_update_by_query“端点来批量更新文档,同时指定pipeline,即可给所有文档添加last_update_time

POST test-index/_update_by_query?pipeline=set-last-update-time-pipeline
{
  "query": {
    "match_all": {}
  }
}

下面是更新后的文档结果

{
  "took": 0,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 2,
      "relation": "eq"
    },
    "max_score": 1,
    "hits": [
      {
        "_index": "test-index",
        "_id": "1",
        "_score": 1,
        "_source": {
          "title": "new doc1",
          "last_update_time": "2024-04-15T08:17:24.527237Z"
        }
      },
      {
        "_index": "test-index",
        "_id": "2",
        "_score": 1,
        "_source": {
          "title": "new doc2",
          "last_update_time": "2024-04-15T08:17:24.528187Z"
        }
      }
    ]
  }
}

4.3 索引映射指定pipeline

如果不想每次写入和更新时都指定Pipeline,也可以在创建索引时指定Pipeline,如下示例:

PUT test-index
{
  "settings": {
    "index":{
      "default_pipeline":"set-last-update-time-pipeline"
    }
  }, 
  "mappings": {
    "properties": {
      "title":{
        "type": "keyword"
      }
    }
  }
}

索引文档或更新文档时,会自动触发对应的Pipeline对文档进行预处理。如下示例,写入两篇文档不指定Pipeline

POST test-index/_doc/1
{
  "title":"new doc1"
}
POST test-index/_doc/2
{
  "title":"new doc2"
}

检索文档发现均已添加last_update_time字段

[
  {
    "_index": "test-index",
    "_id": "1",
    "_score": 1,
    "_source": {
      "title": "new doc1",
      "last_update_time": "2024-04-15T08:21:49.591599Z"
    }
  },
  {
    "_index": "test-index",
    "_id": "2",
    "_score": 1,
    "_source": {
      "title": "new doc2",
      "last_update_time": "2024-04-15T08:21:49.592733Z"
    }
  }
]

4.4 reindex指定pipeline

Elasticsearch提供了reindex API用于将一个索引的文档复制到另一个索引,reindex过程也可以指定Pipeline在写入目标索引前进行预处理。

如下示例,先定义源索引以及写入两篇文档

PUT source-index
{
  "mappings": {
    "properties": {
      "title":{
        "type": "keyword"
      }
    }
  }
}

POST source-index/_doc
{
  "title":"doc1"
}
POST source-index/_doc
{
  "title":"doc2"
}

接着定义目标索引,映射新增last_update_time字段

PUT dest-index
{
  "mappings": {
    "properties": {
      "title":{
        "type": "keyword"
      },
      "last_update_time":{
        "type": "date"
      }
    }
  }
}

然后调用reindex API完成文档迁移

POST _reindex
{
  "source": {
    "index": "source-index"
  },
  "dest": {
    "index": "dest-index",
    "pipeline": "set-last-update-time-pipeline"
  }
}

最后查看dest-index文档数据,发现均添加last_update_time字段

[
  {
    "_index": "dest-index",
    "_id": "glfh4I4BXAgLe9UUkOwp",
    "_score": 1,
    "_source": {
      "title": "doc1",
      "last_update_time": "2024-04-15T08:43:18.905182Z"
    }
  },
  {
    "_index": "dest-index",
    "_id": "g1fh4I4BXAgLe9UUkuy1",
    "_score": 1,
    "_source": {
      "title": "doc2",
      "last_update_time": "2024-04-15T08:43:18.906068Z"
    }
  }
]

5. 尾巴

Ingest Pipelines 是Elasticsearch一个非常实用的功能,它类似于大数据中的ETL,在真正索引数据前,先经过Pipeline完成数据的清洗和加工,把原始数据转换成我们想要的格式再索引,利于后续的数据分析。默认情况下,所有节点都具备Ingest能力,如果要预处理大量文档,建议部署专门的ingest节点,避免影响到主数据节点。


原文地址:https://blog.csdn.net/qq_32099833/article/details/142958068

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