SLOG Handler with more knobs

As great as log/slog is, the provided handlers don't have enough customization knobs. This tries to provide more flexibility to the user.

Installation

go get disorder.dev/shandler

Features

WithJSON

Enables JSON output for the log message. This is useful for structured logging.

WithLogLevel

Controls the log level for the message. This is useful for filtering messages.

WithTimeFormat

Controls the time format for the messages.

WithTextOutputFormat

This is a format string that gets used in text based logs. It takes 3 strings: time, level, and message (in that order). Include a newline at the end of your string.

WithStdOut

Controls which io.Writer is used for non-error log messages.

WithStdErr

Controls which io.Writer is used for error messages.

WithColor

Adds color to the log levels in text mode

With{Debug|Info|Warn|Error}Color

Overrides the default color for the log level.

WithShortLevels

Prints 3 character log levels instead of the full name. In text mode, this helps keep the log lines visually straight.

WithPid

Adds the process ID to the log message.

WithGroupRightJustify

Right justifies the log group name. This is useful for visually grouping log messages. Will attempt to calculate terminal width; if an error occurs, it will default to 80 characters. Overrides WithGroupTextOutputFormat

Examples

logger = slog.New(shandler.NewHandler(
 shandler.WithLogLevel(slog.LevelDebug),
 shandler.WithTimeFormat(time.RFC822),
 shandler.WithTextOutputFormat("%s | %s | %s\n"),
 shandler.WithStdErr(os.Stdout),
))
logger.With(slog.String("app", "myapp")).Debug("test")

Trace Log Level

Library includes an easier way to log trace messages. This is useful for debugging chatty logs.

logger = slog.New(shandler.NewHandler(
 shandler.WithLogLevel(shandler.LevelTrace),
))
logger.Log(context.Background(), shandler.LevelTrace, "trace test")

Benchmarks if you're into that sort of thing

goos: linux
goarch: amd64
pkg: disorder.dev/shandler
cpu: 13th Gen Intel(R) Core(TM) i9-13900H

BenchmarkHandlers/handler_text_log-20            3211198               351.4 ns/op
BenchmarkHandlers/stdlib_text_log-20             3325005               356.1 ns/op
BenchmarkHandlers/handler_json_log-20            2108128               592.3 ns/op
BenchmarkHandlers/stdlib_json_log-20             3445792               379.6 ns/op

PASS
ok      disorder.dev/shandler   6.604s

The JSON Handler here is much slower as it uses the JSON library under the covers. The stdlib implementation builds the string manually, so its faster. 🤷🏼‍♀️