Ian Chen

環境

• ASP.NET Core 3.1
• NLog.Web.AspNetCore 4.9.3
• ElasticSearch 7.8

Nuget

安裝Nuget套件

dotnet add package NLog.Web.AspNetCore
dotnet add package NLog.Targets.ElasticSearch

NLog.config

加上 ElasticSearch 的 target，相關參數說明可參考 NLog.Targets.ElasticSearch 的 GitHub Wiki

<target name="ElasticSearch"
        xsi:type="ElasticSearch"
        index="nlog-elk-${date:format=yyyy.MM.dd}"
        documentType="logevent"
        includeAllProperties="true"
        layout="[${date:format=yyyy-MM-dd HH\:mm\:ss}][${level}] ${logger} ${message} ${exception:format=toString}">
    <field name="MachineName" layout="${machinename}" />
    <field name="ClientIp" layout="${aspnet-request-ip}" />
    <field name="TraceId" layout="${aspnet-TraceIdentifier}" />
    <field name="Time" layout="${longdate}" />
    <field name="level" layout="${level:uppercase=true}" />
    <field name="logger" layout=" ${logger}" />
    <field name="message" layout=" ${message}" />
    <field name="exception" layout=" ${exception:format=toString}" />
    <field name="processid" layout=" ${processid}" />
    <field name="threadname" layout=" ${threadname}" />
    <field name="stacktrace" layout=" ${stacktrace}" />
    <field name="Properties"
           layout="${machinename} ${longdate} ${level:uppercase=true} ${logger} ${message} ${exception}|${processid}|${stacktrace}|${threadname}" />
</target>

記得加上 roles

<rules>
    <logger name="*" minlevel="Info" writeTo="ElasticSearch" />
</rules>

ElasticSearch Url

查閱到 ElasticSearch 的 Url 設定，目前有看到有幾種方式

1. 在 target 指定 ConnectionStringName，並且在 appsetting.json 指定對應的連線位置

2. 在 target 指定 url，值則是透過 Layout Renderer 取得，需要安裝 nuget package

NLog.Extensions.Logging

<target name="ElasticSearch"
        xsi:type="ElasticSearch"
        url="${configsetting:item=ConnectionStrings.ElasticUrl}"
>
...
</target>

3. 直接在Nlog.config指定實際位址

<target name="ElasticSearch"
        xsi:type="ElasticSearch"
        url="http://127.0.0.1:9200/"
>
...
</target>

4. 從 Startup 直接指定 url 的值

public void Configure(IApplicationBuilder app, ILogger<Startup> logger)
{
    var logFactory = LogManager.LoadConfiguration("NLog.config");
    var target = (ElasticSearchTarget)logFactory.Configuration.FindTargetByName("ElasticSearch");
    target.Uri = Configuration["Elastic:Url"];
}

// appsetting.json
"Elastic": {
    "Url":"http://127.0.0.1:9200/"
}

個人測試只有3跟3可以正常運作，考慮不同環境會有需要不同的ElasticSearch Url，故最後採用第4種做法

NLog.Targets.ElasticSearch GitHub