使用 log4j2 编写自定义 json 消息的最佳方法

Question

我一直在将 log4j 用于不同类型的项目，并且对 log4j2 有一些经验。所有实现都使用默认的附加程序和布局。目前我需要编写一个以 json 格式写入的应用程序。所以我通过设置一个非常简单的 log4j2 记录器尝试了 log4j2 JSONLayout 布局。

public class JSONLogger {

    private static final Logger LOGGER = LogManager.getLogger();

    public static void main(String[] args) {
        JSONLogger jsonlogger = new JSONLogger() ;
    }

    public JSONLogger() {
        LOGGER.log(Level.FATAL, "hi mum!") ;

         int val1 = 10, val2 = 11, val3 = 12;

         LOGGER.log(Level.FATAL,"val1={}, val2={}, val3={}", val1, val2, val3);
    }

}

jsonLoggerProperties.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG">
    <Properties>
        <Property name="log-path">/Users/petervannes/NetBeansProjects/JSONLogger/logfiles</Property>
    </Properties>

    <Appenders>
        <RollingFile name="json_file_appender" fileName="${log-path}/jsonlogger.json"
                     filePattern="${log-path}/%d{yyyyMMdd}_jsonlogger-%i.json" >
            <JSONLayout complete="true" compact="false"/>
            <Policies>
                <SizeBasedTriggeringPolicy size="1 KB" />
            </Policies>
            <DefaultRolloverStrategy max="4"/>
        </RollingFile>

    </Appenders>


    <Loggers>
        <root level="debug" additivity="false">
            <AppenderRef ref="json_file_appender"/>
        </root>
    </Loggers>
</Configuration>

导致类似的日志条目；

, {
  "timeMillis" : 1474573600359,
  "thread" : "main",
  "level" : "FATAL",
  "loggerName" : "JSONLogger",
  "message" : "val1=10, val2=11, val3=12",
  "contextStack" : [ "fieldName2" ],
  "endOfBatch" : false,
  "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",
  "threadId" : 1,
  "threadPriority" : 5
}

我需要的是记录成这样的 JSON 格式；

, {
  "DateTime" : "08/01/2016 21:33:22.334",
  "level" : "FATAL",
  "Summary" : "Something has gone wrong",
  "ChainManager" : "Manager A",
  "Optionals" : { "Key_1": "Value1",
                  "Key_2": "Value2" }
}

这可能与 log4j2 JSONLayout 或是否有任何其他布局我可以使用来获得这种格式？

Answer 1

问题是关于使用 log4j2 编写自定义 json 消息。

从 log4j2 版本的 2.11 版本开始这是可能的：

https://issues.apache.org/jira/browse/LOG4J2-2190

JSONLayout的新参数被调用

objectMessageAsJsonObject

。 示例项目文件；

log4j2.properties

status = error


appender.ana_whitespace.type = RollingFile
appender.ana_whitespace.name = ana_whitespace
appender.ana_whitespace.fileName = ${sys:es.logs.base_path:-target}${sys:file.separator}ana_whitespace.log
appender.ana_whitespace.layout.type = JsonLayout
appender.ana_whitespace.layout.propertiesAsList = false
appender.ana_whitespace.layout.compact = false
appender.ana_whitespace.layout.eventEol = true
appender.ana_whitespace.layout.objectMessageAsJsonObject = true
appender.ana_whitespace.layout.complete= true
appender.ana_whitespace.layout.properties= true
appender.ana_whitespace.filePattern = ${sys:es.logs.base_path:-target}${sys:file.separator}ana_whitespace-%d{yyyy-MM-dd}.log
appender.ana_whitespace.filter.1.type = MarkerFilter
appender.ana_whitespace.filter.1.onMismatch=DENY
appender.ana_whitespace.filter.1.onMatch=ACCEPT
appender.ana_whitespace.filter.1.marker=ANA_WHITESPACE
appender.ana_whitespace.policies.type = Policies
appender.ana_whitespace.policies.time.type = TimeBasedTriggeringPolicy
appender.ana_whitespace.policies.time.interval = 1
appender.ana_whitespace.policies.time.modulate = true
appender.ana_whitespace.policies.size.type = SizeBasedTriggeringPolicy
appender.ana_whitespace.policies.size.size = 10 MB

rootLogger.level = info
rootLogger.appenderRef.ana_whitespace.ref = ana_whitespace

Java 代码示例

package de.es.stemmer;

import java.io.IOException;
import java.util.Map;
import java.util.TreeMap;

import org.apache.http.client.ClientProtocolException;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.MarkerManager;
import org.apache.logging.log4j.ThreadContext;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.message.ObjectMessage;

public class JsonLoggerTest {
    final static Logger log = LogManager.getLogger(JsonLoggerTest.class);
    final static Marker MARKER_WHITESPACE = MarkerManager.getMarker("ANA_WHITESPACE");

    public static void main(String[] args) throws ClientProtocolException, IOException {
        System.setProperty("es.logs.base_path", "target");
        System.setProperty("es.logs.cluster_name", "_cluster");
        LoggerContext.getContext().reconfigure();
        ThreadContext.put("orig", "MDC_origValue");
        ThreadContext.put("source", "MDC_sourceSnippet");
        Map<String, String> map = new TreeMap<>();
        map.put("orig", "msg_origValue");
        map.put("source", "msg_sourceSnippet");
        ObjectMessage msg = new ObjectMessage(map);
        log.info(MARKER_WHITESPACE, msg);
        ThreadContext.remove("orig");
        ThreadContext.remove("source");
    }

}

JSON 日志条目

[
{
  "thread" : "main",
  "level" : "INFO",
  "loggerName" : "de.es.stemmer.JsonLoggerTest",
  "marker" : {
    "name" : "ANA_WHITESPACE"
  },
  "message" : {
    "orig" : "msg_origValue",
    "source" : "msg_sourceSnippet"
  },
  "endOfBatch" : false,
  "loggerFqcn" : "org.apache.logging.log4j.spi.AbstractLogger",
  "instant" : {
    "epochSecond" : 1526576578,
    "nanoOfSecond" : 184000000
  },
  "contextMap" : {
    "orig" : "MDC_origValue",
    "source" : "MDC_sourceSnippet"
  },
  "threadId" : 1,
  "threadPriority" : 5
}

]

Answer 2

如果您正在寻找一种方法来生成自定义 JSON 日志消息，而不会添加任何由 log4j2 添加的“噪音”，您可以创建Message 接口的实现并使用不同的布局 - 例如PatternLayout。下面是这种方法的一个例子：

首先一个类来实现Message inferface

import java.util.HashMap;
import java.util.Map;

import org.apache.logging.log4j.message.Message;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class JSONMessage implements Message {

    private static final long serialVersionUID = 538439258494853324L;
    private String messageString;
    private static final Gson GSON = new GsonBuilder()
            .setPrettyPrinting()
            .create();

    public JSONMessage(){
        this(null);
    }

    public JSONMessage(Object msgObj){
        parseMessageAsJson(msgObj);
    }

    public JSONMessage(String msgStr){
        Map<String,String> msgObj = new HashMap<>();
        msgObj.put("message", msgStr);
        parseMessageAsJson(msgObj);
    }

    private void parseMessageAsJson(Object msgObj){
        messageString = GSON.toJson(msgObj);
    }

    @Override
    public String getFormattedMessage() {
        return messageString;
    }

    @Override
    public String getFormat() {
        return messageString;
    }

    @Override
    public Object[] getParameters() {
        return null;
    }

    @Override
    public Throwable getThrowable() {
        return null;
    }

}

接下来是log4j2.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" name="App">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
                <PatternLayout pattern="%m%n" />
        </Console>
    </Appenders>

    <Loggers>
        <Root level="trace">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

现在是一个简单的应用程序类来生成日志事件

import java.util.HashMap;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;


public class App {

    private static final Logger logger = LogManager.getLogger();

    public static void main( String[] args )
    {
        HashMap<String,Object> msgMap = new HashMap<>();
        msgMap.put("someInt", 123);
        msgMap.put("note", "Maybe you put a message here");

        HashMap<String,Object> anotherMap = new HashMap<>();
        anotherMap.put("key1", "value1");
        anotherMap.put("key2", "value2");
        msgMap.put("map", anotherMap);
        logger.info(new JSONMessage(msgMap));
    }
}

这是一些示例输出：

{
  "note": "Maybe you put a message here",
  "map": {
    "key1": "value1",
    "key2": "value2"
  },
  "someInt": 123
}

请注意，我使用Gson 创建 JSON 输出，但您可以使用任何您想要的库。另请注意，此代码不会生成“完整” JSON，因为它不会在日志的开头和结尾添加方括号或消息对象之间的逗号。

Answer 3

我找到了适合我的解决方案； slf4j-json-logger。 它是一个 slf4j 框架，所以应该包含在 pom.xml 中。 示例项目文件；

pom.xml

  <?xml version="1.0" encoding="UTF-8"?>
  <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.reddipped</groupId>
     <artifactId>JSONLogger_2</artifactId>
     <version>1.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.6</maven.compiler.source>
        <maven.compiler.target>1.6</maven.compiler.target>

        <mainClass>com.reddipped.jsonlogger_2.Test</mainClass>

        <slf4j.version>1.7.21</slf4j.version>
        <!-- current log4j 2 release -->
        <log4j.version>2.6.2</log4j.version> 

     </properties>

     <dependencies>
        <dependency>
           <groupId>org.slf4j</groupId>
           <artifactId>slf4j-api</artifactId>
           <version>${slf4j.version}</version>
        </dependency>
        <!-- Binding for Log4J -->
        <dependency>
           <groupId>org.apache.logging.log4j</groupId>
           <artifactId>log4j-slf4j-impl</artifactId>
           <version>${log4j.version}</version>
        </dependency>
        <!-- Log4j API and Core implementation required for binding -->
        <dependency>
           <groupId>org.apache.logging.log4j</groupId>
           <artifactId>log4j-api</artifactId>
           <version>${log4j.version}</version>
        </dependency>
        <dependency>
           <groupId>org.apache.logging.log4j</groupId>
           <artifactId>log4j-core</artifactId>
           <version>${log4j.version}</version>
        </dependency>
        <!-- Logger slf4j-json-logger -->
        <dependency>
           <groupId>com.savoirtech.logging</groupId>
           <artifactId>slf4j-json-logger</artifactId>
           <version>2.0.2</version>
        </dependency>
     </dependencies> 
  </project>

log4j2.xml

  <?xml version="1.0" encoding="UTF-8"?>

  <!--

  Use java property log4j.configurationFile to specify log4j2.xml location
  if not available in classpath

  -    Dlog4j.configurationFile="/Users/petervannes/NetBeansProjects/JSONLogger_2/src/mann/java/resources/log4j2.xml"

  -->
  <configuration status="trace">
     <Properties>
        <Property name="log-path">/Users/petervannes/NetBeansProjects/JSONLogger_2/logfiles</Property>
     </Properties>
     <appenders>
        <RollingFile name="RollingFile" fileName="${log-path}/jsonlogger.json"
                  filePattern="${log-path}/%d{yyyyMMdd}_jsonlogger-%i.json" >
           <PatternLayout>
              <pattern>%m%n</pattern>
           </PatternLayout> 
           <Policies>
              <TimeBasedTriggeringPolicy />
              <SizeBasedTriggeringPolicy size="1 KB" />
           </Policies>
           <DefaultRolloverStrategy max="4"/>
        </RollingFile>
     </appenders>
     <Loggers>
        <Logger name="JSONLogger" level="debug" additivity="false">
           <AppenderRef ref="RollingFile" />
        </Logger>
        <Root level="debug">
           <AppenderRef ref="RollingFile" />
        </Root>
     </Loggers>
  </configuration>

Java 代码示例

  package com.reddipped.jsonlogger_2;

  import com.savoirtech.logging.slf4j.json.LoggerFactory;
  import java.util.HashMap;
  import java.util.Map;

  /**
   *
   * @author petervannes
   */
  public class Test {
      public static void main(String[] args) {   
        Test t = new Test() ;
     }


     public Test() {

        LoggerFactory.setIncludeLoggerName(false);
        LoggerFactory.setDateFormatString("yyyy-MM-dd HH:mm:ss.SSS");

         com.savoirtech.logging.slf4j.json.logger.Logger LOGGER =  LoggerFactory.getLogger("JSONLogger");

     Map<String, String> optionalFields = new HashMap();
     optionalFields.put("CaseNumber", "C12.12343");
     optionalFields.put("Step","Assignment") ;
     optionalFields.put("Department","BPM") ;

     String LOB = "Business Administration" ;
     String Service = "DocumentService" ;
     String Process = "AddAttachements" ;
     String Reason = "Technical" ; 

     LOGGER.error().message("Conversion error 'incompatible PDF document'")
           .field("LOB",LOB)
           .field("Service", Service)
           .field("Process",Process)
           .field("Reason", Reason)
           .map("OptionalFields", optionalFields).log() ;
     }

  }

JSON 日志条目

  {
    "message": "Conversion error  'incompatible PDF document'",
    "LOB": "Business Administration",
    "Service": "DocumentService",
    "Process": "AddAttachements",
    "Reason": "Technical",
    "OptionalFields": {
     "Step": "Assignment",
     "Department": "BPM",
     "CaseNumber": "C12.12343"
    },
    "level": "ERROR",
    "thread_name": "main",
    "class": "com.reddipped.jsonlogger_2.Test",
    "@timestamp": "2016-09-23 10:18:06.623"
  }

Answer 4

我知道这是一个老问题，但我认为有更好的方法。

您应该使用JSON Template Layout。

然后您就可以使用这样的模板来配置您的 JsonLayout：

{
  "mdc": {
    "$resolver": "mdc"
  },
  "exception": {
    "exception_class": {
      "$resolver": "exception",
      "field": "className"
    },
    "exception_message": {
      "$resolver": "exception",
      "field": "message"
    },
    "stacktrace": {
      "$resolver": "exception",
      "field": "stackTrace",
      "stackTrace": {
        "stringified": true
      }
    }
  },
  "line_number": {
    "$resolver": "source",
    "field": "lineNumber"
  },
  "class": {
    "$resolver": "source",
    "field": "className"
  },
  "@version": 1,
  "source_host": "${hostName}",
  "message": {
    "$resolver": "message",
    "stringified": true
  },
  "thread_name": {
    "$resolver": "thread",
    "field": "name"
  },
  "@timestamp": {
    "$resolver": "timestamp"
  },
  "level": {
    "$resolver": "level",
    "field": "name"
  },
  "file": {
    "$resolver": "source",
    "field": "fileName"
  },
  "method": {
    "$resolver": "source",
    "field": "methodName"
  },
  "logger_name": {
    "$resolver": "logger",
    "field": "name"
  }
}

有许多使用模板可用的配置。

在此处查看更多信息：

https://logging.apache.org/log4j/2.x/manual/json-template-layout.html