Skip to main content

One post tagged with "log"

View All Tags

iioter

NLog是.Net中最流行的日志记录开源项目(之一),它灵活免费开源

官方支持文件网络(Tcp、Udp)、数据库控制台等输出

社区支持ElasticSeq等日志平台输出

实时日志需求

在工业物联网等特定场景下需要实时获取日志信息

工业物联网领域常用的是mqtt协议

那我们就使用NLog 自定义一个Target,将日志输出到MqttServer

Web通过Mqtt(websocket)实时获取日志,而不是传统的通过WebApi轮询日志

Web-Log

NLog自定义Target

  1. 官方文档介绍了如何自定义Target,可以获取到一串日志消息,无法获取结构化消息
  2. 需要时用使用自定义Field来完成这部分工作
Field.cs
/// <summary>
/// Additional field details
/// </summary>
[NLogConfigurationItem]
public class Field
{
/// <summary>
/// Name of additional field
/// </summary>
[RequiredParameter]
public string Name { get; set; }

/// <summary>
/// Value with NLog <see cref="NLog.Layouts.Layout"/> rendering support
/// </summary>
[RequiredParameter]
public Layout Layout { get; set; }

/// <summary>
/// Custom type conversion from default string to other type
/// </summary>
/// <remarks>
/// <see cref="System.Object"/> can be used if the <see cref="Layout"/> renders JSON
/// </remarks>
public Type LayoutType { get; set; } = typeof(string);

/// <inheritdoc />
public override string ToString()
{
return $"Name: {Name}, LayoutType: {LayoutType}, Layout: {Layout}";
}
}
  1. 重写Write方法
MqttTarget.cs
protected override void Write(LogEventInfo logEvent)
{
//default fields
Dictionary<string, object> logDictionary = new()
{
{ "timestamp", logEvent.TimeStamp },
{ "level", logEvent.Level.Name },
{ "message", RenderLogEvent(Layout, logEvent) }
};

//customer fields
//这里都处理为字符串了,有优化空间
foreach (var field in Fields)
{
var renderedField = RenderLogEvent(field.Layout, logEvent);

if (string.IsNullOrWhiteSpace(renderedField))
continue;

logDictionary[field.Name] = renderedField;
}

SendTheMessage2MqttBroker(JsonConvert.SerializeObject(logDictionary));
}

使用

下面将使用Nlog.Target.MQTT,演示通过web实时查看应用程序的日志

  1. 创建WebApi项目
  2. 引用NLog.Target.MQTT

nuget

  1. 配置文件
nlog.config
<extensions>
<add assembly="NLog.Web.AspNetCore"/>
<!--<add assembly="NLog.Targets.MQTT"/>-->
<add assembly="NLog.Targets.MQTT"/>
</extensions>

<!-- the targets to write to -->
<targets>
<!-- MQTT Target -->
<target xsi:type="MQTT" name="mqtt" host="localhost" port="1883" username="UserName" password="Password" topic="log"
layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${level:uppercase=true}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}|${callsite}" >
<field name="machine" layout="${machinename}" />
<field name="processid" layout="${processid}" />
<field name="threadname" layout="${threadname}" />
<field name="logger" layout="${logger}" />
<field name="callsite" layout="${callsite-linenumber}" />
<field name="url" layout="${aspnet-request-url}" />
<field name="action" layout="${aspnet-mvc-action}" />
<field name="level" layout="${level:uppercase=true}" />
<field name="message" layout="${message}" />
<field name="exception" layout="${exception:format=toString}" />
</target>
</targets>

<!-- rules to map from logger name to target -->
<rules>
<logger name="*" minlevel="Trace" writeTo="mqtt" />
</rules>
  1. 配置MQTTServer和NLog
Program.cs
// ...
// NLog: Setup NLog for Dependency injection
builder.Logging.ClearProviders();
builder.Logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
builder.Host.UseNLog();

//AddHostedMqttServer
builder.Services.AddHostedMqttServer(mqttServer =>
{
mqttServer.WithoutDefaultEndpoint();
})
.AddMqttConnectionHandler()
.AddConnections();

//Config Port
builder.WebHost.UseKestrel(option =>
{
option.ListenAnyIP(1883, l => l.UseMqtt());
option.ListenAnyIP(80);
});
var app = builder.Build();

// ...
//UseStaticFiles html js etc.
app.UseStaticFiles();
app.UseRouting();

//Websocket Mqtt
app.UseEndpoints(endpoints =>
{
//MqttServerWebSocket
endpoints.MapConnectionHandler<MqttConnectionHandler>("/mqtt", options =>
{
options.WebSockets.SubProtocolSelector = MqttSubProtocolSelector.SelectSubProtocol;
});
});
// ...
  1. Web连接MqttServer
index.html
// ...    
<script src="./jquery.min.js"></script>
<script src="./mqtt.min.js"></script>
<script src="./vue.js"></script>
// ...

var client = mqtt.connect('ws://' + window.location.host + '/mqtt', options);
client.on('connect',
function() {
client.subscribe('log',
function(err) {
if (!err) {
console.log("subed!");
} else {
alert("subed error!");
}
});
});
client.on('message',
function(topic, message) {
if (topic === 'log') {
if (app.logs.length > 50)
app.logs.length = 0;
app.logs.unshift($.parseJSON(message.toString()));
}
});
// ...
  1. 输出日志
WeatherForecastController.cs
// ...  
_logger.LogDebug("LogDebug!");
_logger.LogError(new Exception("Exception Message!"), "LogError!");

//new thread output log after 500ms
Thread thread = new Thread(ThreadProc);
thread.Name = "My Thread";
thread.Start();
// ...
  1. 实时查看日志 访问index.html

  2. 通过Mqtt客户端订阅日志 sublog

源码

在这里NLog.Targets.MQTT:https://github.com/iioter/NLog.Targets.MQTT

相关链接

[1] NLog.Targets.MQTT:https://github.com/iioter/NLog.Targets.MQTT

[2] IoTGateway-Doc:http://iotgateway.net/blog/NLog

[3] NLog自定义Target:https://github.com/NLog/NLog/wiki/How-to-write-a-custom-target

交流

公众号:工业物联网网关QQ群:895199932
wxqq