elasticsearch - kafka-connect接收器中的ExtractField和Parse JSON

Question

我有mongodb-> kafka connect-> elasticsearch的kafka-connect流，可以从头到尾发送数据，但是有效负载文档是JSON编码的。这是我的原始mongodb文件。

{
  "_id": "1541527535911",
  "enabled": true,
  "price": 15.99,
  "style": {
    "color": "blue"
  },
  "tags": [
    "shirt",
    "summer"
  ]
}

这是我的mongodb源连接器配置:

{
  "name": "redacted",
  "config": {
    "connector.class": "com.teambition.kafka.connect.mongo.source.MongoSourceConnector",
    "databases": "redacted.redacted",
    "initial.import": "true",
    "topic.prefix": "redacted",
    "tasks.max": "8",
    "batch.size": "1",
    "key.serializer": "org.apache.kafka.common.serialization.StringSerializer",
    "value.serializer": "org.apache.kafka.common.serialization.JSONSerializer",
    "key.serializer.schemas.enable": false,
    "value.serializer.schemas.enable": false,
    "compression.type": "none",
    "mongo.uri": "mongodb://redacted:27017/redacted",
    "analyze.schema": false,
    "schema.name": "__unused__",
    "transforms": "RenameTopic",
    "transforms.RenameTopic.type":
      "org.apache.kafka.connect.transforms.RegexRouter",
    "transforms.RenameTopic.regex": "redacted.redacted_Redacted",
    "transforms.RenameTopic.replacement": "redacted"
  }
}

在elasticsearch中，最终看起来像这样:

{
  "_index" : "redacted",
  "_type" : "kafka-connect",
  "_id" : "{\"schema\":{\"type\":\"string\",\"optional\":true},\"payload\":\"1541527535911\"}",
  "_score" : 1.0,
  "_source" : {
    "ts" : 1541527536,
    "inc" : 2,
    "id" : "1541527535911",
    "database" : "redacted",
    "op" : "i",
    "object" : "{ \"_id\" : \"1541527535911\", \"price\" : 15.99,
      \"enabled\" : true, \"tags\" : [\"shirt\", \"summer\"],
      \"style\" : { \"color\" : \"blue\" } }"
  }
}

我想使用2个单一消息转换:

ExtractField抓取object，它是JSON的字符串

一种东西，可以将JSON解析为一个对象，或者让普通的JSONConverter处理它，只要它在Elasticsearch中结构正确即可。

我已经尝试在接收器配置中仅使用 ExtractField来执行此操作，但是我看到kafka记录了此错误

kafka-connect_1       | org.apache.kafka.connect.errors.ConnectException:
Bulk request failed: [{"type":"mapper_parsing_exception",
"reason":"failed to parse", 
"caused_by":{"type":"not_x_content_exception",
"reason":"Compressor detection can only be called on some xcontent bytes or
compressed xcontent bytes"}}]

这是我的elasticsearch接收器连接器配置。在此版本中，我可以正常工作，但必须编写自定义的ParseJson SMT。它运行良好，但是如果有更好的方法或某种方式将内置的东西(转换器，SMT或其他可行的东西)组合在一起使用，我很乐意看到这一点。

{
  "name": "redacted",
  "config": {
    "connector.class":
      "io.confluent.connect.elasticsearch.ElasticsearchSinkConnector",
    "batch.size": 1,
    "connection.url": "http://redacted:9200",
    "key.converter.schemas.enable": true,
    "key.converter": "org.apache.kafka.connect.storage.StringConverter",
    "schema.ignore": true,
    "tasks.max": "1",
    "topics": "redacted",
    "transforms": "ExtractFieldPayload,ExtractFieldObject,ParseJson,ReplaceId",
    "transforms.ExtractFieldPayload.type": "org.apache.kafka.connect.transforms.ExtractField$Value",
    "transforms.ExtractFieldPayload.field": "payload",
    "transforms.ExtractFieldObject.type": "org.apache.kafka.connect.transforms.ExtractField$Value",
    "transforms.ExtractFieldObject.field": "object",
    "transforms.ParseJson.type": "reaction.kafka.connect.transforms.ParseJson",
    "transforms.ReplaceId.type": "org.apache.kafka.connect.transforms.ReplaceField$Value",
    "transforms.ReplaceId.renames": "_id:id",
    "type.name": "kafka-connect",
    "value.converter": "org.apache.kafka.connect.json.JsonConverter",
    "value.converter.schemas.enable": false
  }
}

Answer 1

我不确定您的Mongo连接器。我无法识别类(class)或配置...大多数人可能都使用Debezium Mongo connector

我会这样设置

"connector.class": "com.teambition.kafka.connect.mongo.source.MongoSourceConnector",

"key.serializer": "org.apache.kafka.common.serialization.StringSerializer",
"value.serializer": "org.apache.kafka.common.serialization.JSONSerializer",
"key.serializer.schemas.enable": false,
"value.serializer.schemas.enable": true,

schemas.enable很重要，因此内部Connect数据类可以知道如何与其他格式进行转换。

然后，在接收器中，您再次需要使用JSON De 序列化器(通过转换器)，以便它创建完整的对象而不是纯文本字符串，如在Elasticsearch( {\"schema\":{\"type\":\"string\")中看到的那样。

"connector.class":
  "io.confluent.connect.elasticsearch.ElasticsearchSinkConnector",

"key.converter": "org.apache.kafka.connect.storage.StringConverter",
"key.converter.schemas.enable": false,
"value.converter": "org.apache.kafka.connect.json.JsonConverter",
"value.converter.schemas.enable": true

如果这不起作用，那么您可能必须提前在Elasticsearch中手动创建索引映射，以便它知道如何实际解析要发送的字符串