ASP.NET Core – Logging & Serilog
前言
以前就写过了 , 只是有点乱, 这篇作为整理版.
参考:
docs – Logging in .NET Core and ASP.NET Core
Github – Serilog.AspNetCore
Setting up Serilog in .NET 6
ASP.NET Core Build-in Logging
ASP.NET Core 提供了 Logging 的抽象接口, third party 都会依据抽象来做实现. ASP.NET Core 自己也实现了一套简单的 log, 它只能 log to console. 不能 log to file.
所以绝大部分项目都会搭配一个 third party library, 比如 Serilog.
我们先看看 ASP.NET Core build-in 的 log.
Quick Example
dotnet new webapp -o TestLog
自带的模板首页就有 inject logger 了, 在 OnGet 使用它就可以了.
打开 Visual Studio > View > Output, F5 run 就可以看见了
VS Code
Log Category
每个 log 都有 category 的概念, 在 appsetting.json 可以为每个 category 设置 min level
比如某 category 在 production 的时候 min level 是 warning, 在 dev 的时候是 info.
像上面的注入方式, 它的 category name 是 namespace + class "TestLog.Pages.IndexModel"
如果想自定义的话可以用 factory 来创建 logger
在 appsetting.json 声明 min level
level 的顺序是 Trace
= 0, Debug
= 1, Information
= 2, Warning
= 3, Error
= 4, Critical
= 5, and None
= 6.
None 就是不要 log. Trace 就类似 track 追踪的意思
Serilog
安装
dotnet add package Serilog.AspNetCore
program.cs
var builder = WebApplication.CreateBuilder(args); builder.Host.UseSerilog(); Log.Logger = new LoggerConfiguration() .MinimumLevel.Override("Microsoft", LogEventLevel.Information) .Enrich.FromLogContext() .WriteTo.Console() .CreateLogger(); try { Log.Information("Starting web host"); app.Run(); // 把 app.Run(); 放进来 return 0; } catch (Exception ex) { Log.Fatal(ex, "Host terminated unexpectedly"); return 1; } finally { Log.CloseAndFlush(); }
Serilog 的 config 不是通过 appsetting 设置的, 如果想用 appsetting 来管理可以另外安装一个 DLL, 下面会介绍.
appsetting 里的 log config 是给 ASP.NET Core build-in log 的哦, Serilog 不会读取它来用.
Request Log
Serilog 有一个 build-in 的 request log 取代 ASP.NET Core build-in 的, 因为 ASP.NET Core log 太多了.
先关掉 ASP.NET Core 的
Log.Logger = new LoggerConfiguration() .MinimumLevel.Override("Microsoft", LogEventLevel.Warning) .MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Warning)
然后
app.UseSerilogRequestLogging(options => { options.MessageTemplate = "HTTP {RequestMethod} {RequestPath} responded {StatusCode} in {Elapsed:0} ms"; options.GetLevel = (httpContext, elapsed, ex) => LogEventLevel.Information; options.EnrichDiagnosticContext = (diagnosticContext, httpContext) => { // 这里可以加一点料, 加了 template 就可以用 {RequestHost} 这样 // diagnosticContext.Set("RequestHost", httpContext.Request.Host.Value); // diagnosticContext.Set("RequestScheme", httpContext.Request.Scheme); }; });
通过这个 middleware 每个请求都会被记入下来. middleware 放在 static file middleware 下面, 不然 static file 也会被 log 就不好了.
想更 customize 一下可以参考这个 Adding Useful Information to ASP.NET Core Web API Serilog Logs
Write to File
安装
dotnet add package Serilog.Sinks.File
设置
Log.Logger = new LoggerConfiguration() .WriteTo.File("log.txt", rollingInterval: RollingInterval.Day)
write to file 是马上执行的, 这对 IO 性能不太好.
Async Write to File
所以 Serilog 推出了一个 async 版本. 它会先写入 ram, 等一定量之后才写入 file.
dotnet add package Serilog.Sinks.Async
设置
Log.Logger = new LoggerConfiguration() .WriteTo.Async(a => a.File("log.txt", rollingInterval: RollingInterval.Day, buffered: true), bufferSize: 500)
wrap 起来就可以了, buffered = true, buffer size 默认是 10,000 items 那是多少我也不清楚.
然后在 app 结束前一定要释放哦
try { CreateHostBuilder(args).Build().Run(); } catch (Exception ex) { Log.Fatal(ex, "Host terminated unexpectedly"); } finally { Log.CloseAndFlush(); // 重要 }
Use appsetting.json as Config
安装
dotnet add package Serilog.Settings.Configuration
设置
Log.Logger = new LoggerConfiguration() .ReadFrom.Configuration(builder.Configuration)
appsetting.json
"Serilog": { "Using": [ "Serilog.Sinks.File" ], // 这个在 dotnet core project 下是多余的,可以拿掉哦 "MinimumLevel": { "Default": "Information", "Override": { "Microsoft": "Warning", "Microsoft.AspNetCore": "Warning", "System": "Warning" } }, "WriteTo": [ { "Name": "File", "Args": { "path": "log.txt", "rollingInterval": "Day", "outputTemplate": "[{Timestamp:hh:mm:ss tt} {Level:u3}] {Message:lj} {Properties:j}{NewLine}{Exception}" } }, { "Name": "Async", "Args": { "configure": [ { "Name": "File", "Args": { "path": "log-async.txt", "rollingInterval": "Day", "outputTemplate": "[{Timestamp:hh:mm:ss tt} {Level:u3}] {Message:lj} {Properties:j}{NewLine}{Exception}", "buffered": true } } ] } } ], "Enrich": [ "FromLogContext" ] }