Can you provide custom log level string to SimpleConsoleFormatter

[dearoneesama]

Background and Motivation

I like to use the built-in console logging in production because it is easy and it looks good. The thing that frustrates me when using it is its log level string behaviour. Namely we take the source code as example:

runtime/src/libraries/Microsoft.Extensions.Logging.Console/src/SimpleConsoleFormatter.cs

Line 134 in 3c801a8

private static string GetLogLevelString(LogLevel logLevel)

            return logLevel switch
            {
                LogLevel.Trace => "trce",
                LogLevel.Debug => "dbug",
                LogLevel.Information => "info",
                LogLevel.Warning => "warn",
                LogLevel.Error => "fail",
                LogLevel.Critical => "crit",
                _ => throw new ArgumentOutOfRangeException(nameof(logLevel))
            };

This is hardcoded and, somehow, not as common as things like "DEBUG", "ERROR", etc. For example, when I was using LogDNA, which should automatically parse log and log levels, cannot infer "fail" because it thinks this pattern is not common.

It would be very helpful to make this customisable.

Proposed API

I don't know, probably adding a configuration to SimpleConsoleFormatterOptions is simple enough:

namespace Microsoft.Extensions.Logging.Console
{
    public class SimpleConsoleFormatterOptions : ConsoleFormatterOptions
    {
        public SimpleConsoleFormatterOptions() { }

        public LoggerColorBehavior ColorBehavior { get; set; }

        public bool SingleLine { get; set; }

+        public Func<LogLevel, string> LogLevelStringFormatter { get; set; } 
    }
}

If the user does not set this, we can use the default strings as they are now.

Usage Examples

Like this:

  // builder is ILoggingBuilder
  builder.AddSimpleConsole(options =>
  {
    options.LogLevelStringFormatter = logLevel => logLevel switch
      {
        LogLevel.Trace => "trce",
        LogLevel.Debug => "dbug",
        LogLevel.Information => "info",
        LogLevel.Warning => "warn",
        LogLevel.Error => "fail",
        LogLevel.Critical => "crit",
        _ => "unknown"
      }
  });

Alternative Designs

We can probably use a Dictionary<LogLevel, string>, but we cannot guarantee all types are covered?

Risks

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Issue Details

---

Background and Motivation

I like to use the built-in console logging in production because it is easy and it looks good. The thing that frustrates me when using it is its log level string behaviour. Namely we take the source code as example:

runtime/src/libraries/Microsoft.Extensions.Logging.Console/src/SimpleConsoleFormatter.cs

Line 134 in 3c801a8

private static string GetLogLevelString(LogLevel logLevel)

            return logLevel switch
            {
                LogLevel.Trace => "trce",
                LogLevel.Debug => "dbug",
                LogLevel.Information => "info",
                LogLevel.Warning => "warn",
                LogLevel.Error => "fail",
                LogLevel.Critical => "crit",
                _ => throw new ArgumentOutOfRangeException(nameof(logLevel))
            };

This is hardcoded and, somehow, not as common as things like "DEBUG", "ERROR", etc. For example, when I was using LogDNA, which should automatically parse log and log levels, cannot infer "fail" because it thinks this pattern is not common.

It would be very helpful to make this customisable.

Proposed API

I don't know, probably adding a configuration to SimpleConsoleFormatterOptions is simple enough:

namespace Microsoft.Extensions.Logging.Console
{
    public class SimpleConsoleFormatterOptions : ConsoleFormatterOptions
    {
        public SimpleConsoleFormatterOptions() { }

        public LoggerColorBehavior ColorBehavior { get; set; }

        public bool SingleLine { get; set; }

+        public Func<LogLevel, string> LogLevelStringFormatter { get; set; } 
    }
}

If the user does not set this, we can use the default strings as they are now.

Usage Examples

Like this:

  // builder is ILoggingBuilder
  builder.AddSimpleConsole(options =>
  {
    options.LogLevelStringFormatter = logLevel => logLevel switch
      {
        LogLevel.Trace => "trce",
        LogLevel.Debug => "dbug",
        LogLevel.Information => "info",
        LogLevel.Warning => "warn",
        LogLevel.Error => "fail",
        LogLevel.Critical => "crit",
        _ => "unknown"
      }
  });

Alternative Designs

We can probably use a Dictionary<LogLevel, string>, but we cannot guarantee all types are covered?

Risks

Author:	dearoneesama
Assignees:	-
Labels:	api-suggestion, area-Extensions-Logging, untriaged
Milestone:	-