由于我们的埋点日志是嵌套json类型，要想最终所有字段展开来统计分析就必须把嵌套json展开。

1. 日志格式如下：

2019-01-22 19:25:58 172.17.12.177  /statistics/EventAgent appkey=yiche&enc=0&ltype=view&yc_log={"uuid":"73B333EB-EC87-4F9F-867B-A9BF38CBEBB2","mac":"02:00:00:00:00:00","uid":-1,"idfa":"2BFD67CF-ED60-4CF6-BA6E-FC0B18FDDDF8","osv":"iOS11.4.1","fac":"apple","mdl":"iPhone SE","req_id":"360C8C43-73AC-4429-9E43-2C08F4C1C425","itime":1548156351820,"os":"2","sn_id":"6B937D83-BFB2-4C22-85A8-5B3E82D9D0F1","dvid":"3676b52dc155e1eec3ca514f38736fd6","aptkn":"4fb9b2bffb808515aa0e9a5f5b17d826769e432f63d5cf87f7fb5ce4d67ef9f1","cha":"App Store","idfv":"B1EAD56F-E456-4FF2-A3C2-9A8FA0693C22","nt":4,"lg_vl":{"pfrom":"shouye","ptitle":"shouye"},"av":"10.3.3"}   218.15.255.124  200

2. 最开始Logstash的配置文件如下：

input {
  file {
    path => ["/data/test_logstash.log"]
    type => ["nginx_log"]
    start_position => "beginning"
  }
}
filter {
  if [type] =~ "nginx_log" {
    grok {
      match => { "message" => "%{TIMESTAMP_ISO8601:create_time} %{IP:server_ip}  %{URIPATH:uri} %{GREEDYDATA:args}   %{IP:client_ip}  %{NUMBER:status}" }
    }
    urldecode{
    field =>args
    }
    kv {
    source =>"args"
    field_split =>"&"
    remove_field => [ "args","@timestamp","message","path","@version","path","host" ]
    }
    json {
        source => "yc_log"
        remove_field => [ "yc_log" ]
    }
  }
}
output {
  stdout { codec => rubydebug }
}

按照以上配置文件运行Logstash得到的结果如下：

{
      "server_ip" => "172.17.12.177",
            "cha" => "App Store",
            "mdl" => "iPhone SE",
           "type" => "nginx_log",
            "mac" => "02:00:00:00:00:00",
         "ptitle" => "shouye",
         "appkey" => "yiche",
           "idfv" => "B1EAD56F-E456-4FF2-A3C2-9A8FA0693C22",
          "sn_id" => "6B937D83-BFB2-4C22-85A8-5B3E82D9D0F1",
          "aptkn" => "4fb9b2bffb808515aa0e9a5f5b17d826769e432f63d5cf87f7fb5ce4d67ef9f1",
             "av" => "10.3.3",
             "os" => "2",
           "idfa" => "2BFD67CF-ED60-4CF6-BA6E-FC0B18FDDDF8",
            "uid" => -1,
           "uuid" => "73B333EB-EC87-4F9F-867B-A9BF38CBEBB2",
         "req_id" => "360C8C43-73AC-4429-9E43-2C08F4C1C425",
         "status" => "200",
            "uri" => "/statistics/EventAgent",
            "enc" => "0",
          "ltype" => "view",
          "lg_vl" => {
        "ptitle" => "shouye",
         "pfrom" => "shouye"
    },
             "nt" => 4,
          "pfrom" => "shouye",
          "itime" => 1548156351820,
      "client_ip" => "218.15.255.124",
    "create_time" => "2019-01-22 19:25:58",
           "dvid" => "3676b52dc155e1eec3ca514f38736fd6",
            "fac" => "apple",
       "lg_value" => "{\"pfrom\":\"shouye\",\"ptitle\":\"shouye\"}",
            "osv" => "iOS11.4.1"
}

可以看到lg_vl字段仍然是json格式，没有解析出来。如果直接在配置文件中添加

json { source => "lg_vl" }

会报jsonParseException错。

3. 正确做法

input {
  file {
    path => ["/data/test_logstash.log"]
    type => ["nginx_log"]
    start_position => "beginning"
  }
}
filter {
  if [type] =~ "nginx_log" {
    grok {
      match => { "message" => "%{TIMESTAMP_ISO8601:create_time} %{IP:server_ip}  %{URIPATH:uri} %{GREEDYDATA:args}   %{IP:client_ip}  %{NUMBER:status}" }
    }
    urldecode{
    field =>args
    }
    kv {
    source =>"args"
    field_split =>"&"
    remove_field => [ "args","@timestamp","message","path","@version","path","host" ]
    }
    json {
        source => "yc_log"
        remove_field => [ "yc_log" ]
    }
    mutate {
      add_field => { "lg_value" => "%{lg_vl}" }
    }
    json {
        source => "lg_value"
        remove_field => [ "lg_vl","lg_value" ]
    }
  }
}

output {
  stdout { codec => rubydebug }
}

在解析完上一层json之后添加一个字段lg_value，再将lg_vl的内容赋值给lg_value；之后单独对lg_value进行json解析就可以了。解析完结果如下：

{
           "type" => "nginx_log",
             "nt" => 4,
           "dvid" => "3676b52dc155e1eec3ca514f38736fd6",
             "os" => "2",
            "fac" => "apple",
          "ltype" => "view",
      "client_ip" => "218.15.255.124",
          "itime" => 1548156351820,
            "mac" => "02:00:00:00:00:00",
           "idfa" => "2BFD67CF-ED60-4CF6-BA6E-FC0B18FDDDF8",
            "uri" => "/statistics/EventAgent",
          "aptkn" => "4fb9b2bffb808515aa0e9a5f5b17d826769e432f63d5cf87f7fb5ce4d67ef9f1",
          "sn_id" => "6B937D83-BFB2-4C22-85A8-5B3E82D9D0F1",
    "create_time" => "2019-01-22 19:25:58",
            "osv" => "iOS11.4.1",
         "req_id" => "360C8C43-73AC-4429-9E43-2C08F4C1C425",
         "ptitle" => "shouye",
             "av" => "10.3.3",
      "server_ip" => "172.17.12.177",
          "pfrom" => "shouye",
            "enc" => "0",
            "mdl" => "iPhone SE",
            "cha" => "App Store",
           "idfv" => "B1EAD56F-E456-4FF2-A3C2-9A8FA0693C22",
            "uid" => -1,
           "uuid" => "73B333EB-EC87-4F9F-867B-A9BF38CBEBB2",
         "appkey" => "yiche",
         "status" => "200"
}

完美，棒棒哒！！！