使用logstash的logstash-input-kafka插件读取kafka中的数据

logstash版本为5.5.3，kafka版本为2.11，此版本默认内置了kafka插件，可直接配置使用，不需要重新安装插件；注意logstash5.x版本前后配置不太一样，注意甄别，必要时可去elasticsearch官网查看最新版配置参数的变化，例如logstash5.x版本以前kafka插件配置的是zookeeper地址，5.x以后配置的是kafka实例地址。

input{
      kafka{
        bootstrap_servers => ["192.168.110.31:9092,192.168.110.31:9093,192.168.110.31:9094"]
        client_id => "test"
        group_id => "test"
        auto_offset_reset => "latest" //从最新的偏移量开始消费
        consumer_threads => 5
        decorate_events => true //此属性会将当前topic、offset、group、partition等信息也带到message中
        topics => ["logq","loge"] //数组类型，可配置多个topic
        type => "bhy" //所有插件通用属性,尤其在input里面配置多个数据源时很有用
      }
}

 使用了decorate_events属性，注意看logstash控制台打印的信息，会输出如下

"kafka":{"consumer_group":"test","partition":0,"offset":10430232,"topic":"logq","key":null}

 另外一个input里面可设置多个kafka，

input{
      kafka{
        bootstrap_servers => ["192.168.110.31:9092,192.168.110.31:9093,192.168.110.31:9094"]
        client_id => "test1"
        group_id => "test1"
        auto_offset_reset => "latest"
        consumer_threads => 5
        decorate_events => true
        topics => ["loge"]
        type => "classroom"
      }
      kafka{
        bootstrap_servers => ["192.168.110.31:9092,192.168.110.31:9093,192.168.110.31:9094"]
        client_id => "test2"
        group_id => "test2"
        auto_offset_reset => "latest"
        consumer_threads => 5
        decorate_events => true
        topics => ["logq"]
        type => "student"
      }
}

 假如你在filter模块中还要做其他过滤操作，并且针对input里面的每个数据源做得操作不一样，那你就可以根据各自定义的type来匹配

filter{
        if[type] == "classroom"{
            grok{
               ........
            }
        }
        if[type] == "student"{
            mutate{
               ........
            }
        }
}

 不只filter中可以这样，output里面也可以这样；并且当output为elasticsearch的时候，input里面的定义的type将会成为elasticsearch的你定义的index下的type

output {
        if[type] == "classroom"{
          elasticsearch{
               hosts => ["192.168.110.31:9200"]
               index => "school"
               timeout => 300
               user => "elastic"
               password => "changeme"
          }

        }
        if[type] == "student"{
            ........
        }
 }

 对于第一个存储到elasticsearch的路径为localhost:9200/school/classroom；第二个存储到elasticsearch的路径为localhost:9200/school/student。假如从来没有定义过type，默认的type为logs，访问路径为第一个存储到elasticsearch的路径为localhost:9200/school/logs，默认的type也可不加。