Simple and efficient file logger provider for .NET Core (any version) without additional dependencies.
- very similar to standard ConsoleLogger but writes to a file
- can append to a file
- supports rolling file behaviour and can control total log size
- suitable for intensive concurrent usage: has internal message queue to avoid threads blocking
Add NReco.Logging.File package reference and initialize file logging provider:
| .NET Core 2.x/3.x | .NET Core 1.x |
|---|---|
| In services.AddLogging | In Startup.cs Configure method |
loggingBuilder.AddFile("app.log", append:true);or var loggingSection = Configuration.GetSection("Logging");loggingBuilder.AddFile(loggingSection); |
loggerFactory.AddFile("app.log", append:true);or var loggingSection = Configuration.GetSection("Logging");loggerFactory.AddFile(loggingSection); |
Example of configuration section from appsettings.json:
"Logging": {
"LogLevel": {
"Default": "Debug",
"System": "Information",
"Microsoft": "Error"
},
"File": {
"Path": "app.log",
"Append": "True",
"FileSizeLimitBytes": 0, // use to activate rolling file behaviour
"MaxRollingFiles": 0 // use to specify max number of log files
}
}
This feature is activated with FileLoggerOptions properties: FileSizeLimitBytes and MaxRollingFiles. Lets assume that file logger is configured for "test.log":
- if only
FileSizeLimitBytesis specified file logger will create "test.log", "test1.log", "test2.log" etc - use
MaxRollingFilesin addition toFileSizeLimitBytesto limit number of log files; for example, for value "3" file logger will create "test.log", "test1.log", "test2.log" and again "test.log", "test1.log" (old files will be overwritten).
You can specify FileLoggerProvider.FormatLogEntry handler to customize log entry content. For example, it is possible to write log entry as JSON array:
loggerFactory.AddProvider(new NReco.Logging.File.FileLoggerProvider("logs/app.js", true) {
FormatLogEntry = (msg) => {
var sb = new System.Text.StringBuilder();
StringWriter sw = new StringWriter(sb);
var jsonWriter = new Newtonsoft.Json.JsonTextWriter(sw);
jsonWriter.WriteStartArray();
jsonWriter.WriteValue(DateTime.Now.ToString("o"));
jsonWriter.WriteValue(msg.LogLevel.ToString());
jsonWriter.WriteValue(msg.EventId.Id);
jsonWriter.WriteValue(msg.Message);
jsonWriter.WriteValue(msg.Exception?.ToString());
jsonWriter.WriteEndArray();
return sb.ToString();
}
});
(in case of .NET Core 2 use loggingBuilder.AddProvider instead of loggerFactory.AddProvider).
Copyright 2017-2020 Vitaliy Fedorchenko and contributors
Distributed under the MIT license