README
¶
🌈 slogcolor
slogcolor is a little, customizable color handler for log/slog. It enhances log readability by color-coding log levels and supports flexible formatting options.
Its output is inspired by XMRig and zerolog.
Installation
Run:
go get -u github.com/otheroffram/slogcolor
Basic Usage
package main
import (
"os"
"time"
"errors"
"log/slog"
"github.com/otheroffram/slogcolor"
)
func main() {
// Configure slog to use slogcolor by default for colored output
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, slogcolor.DefaultOptions)))
slog.Info("Initializing")
slog.Debug("Init done", "duration", 500*time.Millisecond)
slog.Warn("Slow request!", "method", "GET", "path", "/api/users", "duration", 750*time.Millisecond)
slog.Error("DB connection lost!", "err", errors.New("connection reset"), "db", "horalky")
}
Default options
slogcolor provides a set of predefined options to simplify configuration. You can use these default options via DefaultOptions, or simply pass nil for the same effect.
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, slogcolor.DefaultOptions)))
// or
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, nil)))
The behavior is identical in both cases, so you can choose based on your coding style or preference.
Customized output format
The output format can also be customized using the Options like this:
opts := &slogcolor.Options{
Level: slog.LevelDebug,
TimeFormat: time.RFC3339,
SrcFileMode: slog.Nop,
}
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, opts)))
or like this:
opts := slogcolor.DefaultOptions
opts.Level = slog.LevelDebug
opts.TimeFormat = time.RFC3339
opts.SrcFileMode = slog.Nop
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, opts)))
Prefixes
Prefixes can be useful for adding context to log messages, such as identifying different subsystems or components (e.g., DB, SceneController, Network) that generated the log.
Messages can be prefixed with Prefix like this:
slog.Info(slogcolor.Prefix("MyPrefix", "kajšmentke"))
slog.Info(slogcolor.Prefix("SceneController", "switching scene"), "scene", "MainMenuScene")
// or
slog.Info(slogcolor.Prefix("MyPrefix")+"kajšmentke")
slog.Info(slogcolor.Prefix("SceneController")+"switching scene", "scene", "MainMenuScene")
It can also be used as an alias for ease of use, especially when you frequently use prefixes, like this:
var P = slogcolor.Prefix
slog.Info(P("MyPrefix", "kajšmentke"))
// or
slog.Info(P("MyPrefix")+"kajšmentke")
Disable colors
Colors are enabled by default but can be disabled using Options.NoColor. Particularly useful for automatically enabling colors based on the terminal capabilities using e.g. the go-isatty package.
w := os.Stderr
opts := slogcolor.DefaultOptions
opts.NoColor = !isatty.IsTerminal(w.Fd())
slog.SetDefault(slog.New(slogcolor.NewHandler(w, opts)))
License
Licensed under the MIT License (see LICENSE)
Documentation
¶
Overview ¶
slogcolor implements a color handler for log/slog.
Example ¶
package main
import (
"errors"
"log/slog"
"os"
"time"
"github.com/fatih/color"
"github.com/otheroffram/slogcolor"
)
func main() {
opts := slogcolor.DefaultOptions
opts.Level = slog.LevelDebug
opts.LevelTags = map[slog.Level]string{
slog.LevelInfo: color.New(color.BgCyan, color.FgBlack).Sprint("Info"),
}
slog.SetDefault(slog.New(slogcolor.NewHandler(os.Stderr, opts)))
slog.Info("Initializing")
slog.Debug("Init done", "duration", 500*time.Millisecond)
slog.Warn("Slow request!", "method", "GET", "path", "/api/users", "duration", 750*time.Millisecond)
slog.Error("DB connection lost!", "err", errors.New("connection reset"), "db", "horalky")
}
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var DefaultLevelTags = map[slog.Level]string{ slog.LevelDebug: color.New(color.BgCyan, color.FgHiWhite).Sprint("DEBUG"), slog.LevelInfo: color.New(color.BgGreen, color.FgHiWhite).Sprint("INFO "), slog.LevelWarn: color.New(color.BgYellow, color.FgHiWhite).Sprint("WARN "), slog.LevelError: color.New(color.BgRed, color.FgHiWhite).Sprint("ERROR"), }
DefaultLevelTags are the default level tags.
Functions ¶
Types ¶
type Handler ¶
type Handler struct {
// contains filtered or unexported fields
}
Handler is a colored slog handler.
func NewHandler ¶
NewHandler creates a new Handler with the specified options. If opts is nil, uses DefaultOptions.
type Options ¶
type Options struct {
// Level reports the minimum level to log.
// Levels with lower levels are discarded.
// If nil, the Handler uses [slog.LevelInfo].
Level slog.Leveler
// TimeFormat is the time format.
TimeFormat string
// SrcFileMode is the source file mode.
SrcFileMode SourceFileMode
// SrcFileLength to show fixed length filename to line up the log output, default 0 shows complete filename.
SrcFileLength int
// MsgPrefix to show prefix before message, default: white colored "| ".
MsgPrefix string
// MsgColor is the color of the message, default to empty.
MsgColor *color.Color
// MsgLength to show fixed length message to line up the log output, default 0 shows complete message.
MsgLength int
// NoColor disables color, default: false.
NoColor bool
// LevelTags is level tag for message, default: DefaultLevelStyles
LevelTags map[slog.Level]string
}
Options represents the options passed into NewHandler.
type SourceFileMode ¶
type SourceFileMode int
const ( // Nop does nothing. Nop SourceFileMode = iota // ShortFile produces only the filename (for example main.go:69). ShortFile // LongFile produces the full file path (for example /home/user/go/src/myapp/main.go:69). LongFile )
Source Files
Directories