Overview

Meziantou.Extensions.Logging.FileLogger provides FileLoggerProvider, an ILoggerProvider that writes the log entries to files. The entries are formatted on the thread that logs them, queued, and written by a background thread, so logging does not wait for the disk.

var logsDirectory = Directory.CreateTempSubdirectory("logs").FullName;
await using var provider = new FileLoggerProvider(logsDirectory);

using var loggerFactory = LoggerFactory.Create(builder => builder.AddProvider(provider));
var logger = loggerFactory.CreateLogger("Sample");

logger.LogInformation("Hello from file logger");

// Wait for the background thread to write the pending messages
await provider.FlushAsync();

var logFilePath = provider.LogFilePath;
Assert.NotNull(logFilePath);
Assert.StartsWith(logsDirectory, logFilePath);

• new FileLoggerProvider(directory) creates the provider directly. In an application with a host, register it with AddFile instead: see Configuration.
• FlushAsync waits for the background thread to write the pending messages. Disposing the provider writes them too, then closes the file.
• LogFilePath is the path of the file the messages are written to. It changes when the file is rolled.

Pages

• Configuration: register the provider, and set the options in code or in the configuration.
• Files, rolling and retention: file names, a new file per period or per size, the number of files to keep, and appending to an existing file.
• Compression: compress the files with gzip, Brotli or Zstandard, while they are written or once they are rolled.
• Message format: the content of an entry, the JSON format, and custom formatters.
• Queue and flushing: what happens when the disk is slow, when the messages reach the disk, and how errors are handled.
• Security: the permissions of the files, and messages that contain untrusted data.