SLF4J TTY

A colourful logger provider for SLF4J for making your console log output pretty.

Note this is not intended for logging to a file, although there are options to do so. This provider is focused on console log output'

Requires any modern terminal that has ANSI color and emoticon support.

Who Is This For?

• You have a console application that uses SL4F4J and you want pretty output
• You have a console application that pipes logged output to another application and you want to capture simple log output in a consistent manner.

Features

• Flexible configuration based on INI files.
• Live configuration changes.
• Style a log event according to log priority level.
• Style and decorate any field with color, styles and emoticons.
• Highlight parameters in parameterized log events.
• Output resizes automatically with terminal
• JSON output option

Usage

SLF4J-TTY is in Maven central, so simply add the dependency to your project.

<dependency>
    <groupId>com.sshtools</groupId>
    <artifactId>slf4j-tty</artifactId>
    <version>0.0.3</version>
</dependency>

See badge above for version available on Maven Central. Snapshot versions are in the Sonatype OSS Snapshot Repository.

Design

SLF4J-TTY kind of steps outside of SLF4Js intended design a bit. Usually, any particular provider would actually be an adapter to a separate (existing) logging framework, for example Log4J.

However, given SLF4J has become the de-facto standard, and all the projects I intend to use SLF4J-TTY with use it, I saw little point right now in implementing an entirely new logging framework.

So instead, SLF4J-TTY is more basically more like slf4j-simple, which is the simple provider that implements the SLF4J API directly. The code in fact was based on this provider.

TODO

This is the very first alpha release. There are a few bugs, and incompete areas.

• No way to load defaults from classpath resource.
• Live configuration reloading not implemented.

Configuration

Configuration is achieved using INI format files. The library comes with a pre-defined default, which you can override any and all properties using a resource in your project.

Further configuration may be achieved by the user by creating either a system-wide or user specific file in the usual location for configuration the operating system in use.

Defaults

The defaults used are as follows.

;
; Log
;

[log]
	enabled = TRUE
	default-level = INFO
	output = SYS_ERR
	log-file = 
	
[output]
	style-as-level = TRUE
	gap  = 1
	ellipsis = …
	width = 0
	fallback-width = 132
	parameter-style = @{bold ${parameter}}
	layout = level, short-name, message, thread-name, date-time 
		
[fields]
	[fields.date-time]
		alignment = RIGHT
		type = DATE_TIME
		format = SHORT
		width = 23
		style = @{faint ${date-time}}
	
	[fields.level]
		alignment = LEFT
		width = 9
		style = [${level}]
	
	[fields.thread-id]
		alignment = LEFT
		width = 10
		style = ${thread-id}
	
	[fields.thread-name]
		alignment = LEFT
		width = 15
		style = [${thread-name}]
	
	[fields.message]
		alignment = LEFT
		width = 0
		style =${message}
	
	[fields.markers]
		alignment = LEFT
		width = 0
		style = ${markers}
	
	[fields.name]
		alignment = LEFT
		width = 0
		style = ${name}
	
	[fields.short-name]
		alignment = LEFT
		width = 15
		style = @{bold ${short-name}}
		

[levels]
	name = Levels
	description = Configuration for each of the levels
	
	[levels.TRACE]
		text = 🔍 TRACE
		style = @{faint ${text}}
		
	[levels.DEBUG]
		text = 🐛 DEBUG
		style = @{italic,fg:cyan ${text}}
		
	[levels.INFO]
		text = ℹ️ INFO
		style = @{fg:blue ${text}}
			
	[levels.WARN]
		text = ⚠️ WARN
		style = @{fg:yellow ${text}}
		
	[levels.ERROR] 
		text = ⛔ ERROR
		style = @{bold,fg:red ${text}}
		

Styles Expressions

SLF4J-TTY uses Jline3's StyleExpression for it's style configuration items. With these, you can style the text for the item using any common support ANSI terminal sequence.

Selection Of Styles

• fg
• bg
• blink
• bold
• conceal
• crossed-out
• crossedout
• faint
• hidden
• inverse
• inverse-neg
• inverseneg
• italic
• underline