假设我们有一个已经存在的文档服务，开发语言Node.js，数据储存于Mongodb。现在我们要利用Elasticsearch，为文档增加全文检索功能。

1 为Logstash安装插件

./bin/logstash-plugin.bat install logstash-input-mongodb
./bin/logstash-plugin.bat install logstash-filter-prune

2 将Mongodb中数据导入Elasticsearch

创建logstash.conf文件如下：

input {
    mongodb {
        uri => 'mongodb://localhost:27017/teamup'
        placeholder_db_dir => 'D:/MongoDB/db/'
        placeholder_db_name =>'teamup.db'
        collection => 'documents'
    }
}

filter {
    prune {
        whitelist_names => [ "^_id$", "^markdown$", "^title$" ]
    }
    mutate { 
        rename => ["_id", "id"]
    }
}

output {
    stdout {
       codec => json_lines
    }

    elasticsearch {
        hosts => ["127.0.0.1:9200"]
        index => "teamup"
        manage_template=>true
        document_type => "documents"
    }
}

命令启动logstash：./bin/logstash.bat -f ./logstash.conf，进行数据导入

3 查询

  ret = await esclient.search({
    index: 'documents',
    body: {
      query: {
        match: {
          text: '关键词'
        }
      }
    }
  });